Working with Amazon Ion data types in Amazon QLDB - Amazon Quantum Ledger Database (Amazon QLDB)

Working with Amazon Ion data types in Amazon QLDB

Amazon QLDB stores its data in the Amazon Ion format. To work with data in QLDB, you must use an Ion library as a dependency for a supported programming language.

In this section, learn how to convert data from native types to their Ion equivalents, and the other way around. This reference guide shows code examples that use the QLDB driver to process Ion data in a QLDB ledger. It includes code examples for Java, .NET (C#), Go, Node.js (TypeScript), and Python.

Prerequisites

The following code examples assume that you have a QLDB driver instance that is connected to an active ledger with a table named ExampleTable. The table contains a single existing document that has the following eight fields:

  • ExampleBool

  • ExampleInt

  • ExampleFloat

  • ExampleDecimal

  • ExampleTimestamp

  • ExampleString

  • ExampleBlob

  • ExampleList

Note

For the purposes of this reference, assume that the type stored in each field matches its name. In practice, QLDB doesn't enforce schema or data type definitions for document fields.

Bool

The following code examples show how to process the Ion boolean type.

Java
// Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); boolean exampleBoolean = driver.execute((txn) -> { // Transforming a Java boolean to Ion boolean aBoolean = true; IonValue ionBool = ionSystem.newBool(aBoolean); // Insertion into QLDB txn.execute("UPDATE ExampleTable SET ExampleBool = ?", ionBool); // Fetching from QLDB Result result = txn.execute("SELECT VALUE ExampleBool from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Transforming Ion to a Java boolean // Cast IonValue to IonBool first aBoolean = ((IonBool)ionValue).booleanValue(); } // exampleBoolean is now the value fetched from QLDB return aBoolean; });
.NET
using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; ... IValueFactory valueFactory = new ValueFactory(); // Transforming a C# bool to Ion. bool nativeBool = true; IIonValue ionBool = valueFactory.NewBool(nativeBool); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleBool = ?", ionBool); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleBool from ExampleTable"); }); bool? retrievedBool = null; // Assume there is only one document in ExampleTable. await foreach (IIonValue ionValue in selectResult) { // Transforming Ion to a C# bool. retrievedBool = ionValue.BoolValue; }
Note

To convert to synchronous code, remove the await and async keywords, and change the IAsyncResult type to IResult.

Go
exampleBool, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aBool := true // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleBool = ?", aBool) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleBool FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { var decodedResult bool err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleBool is now the value fetched from QLDB return decodedResult, nil } return nil, result.Err() })
Node.js
async function queryIonBoolean(driver: QldbDriver): Promise<boolean> { return (driver.executeLambda(async (txn: TransactionExecutor) => { // Updating QLDB await txn.execute("UPDATE ExampleTable SET ExampleBool = ?", true); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT VALUE ExampleBool FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // Transforming Ion to a TypeScript Boolean const boolValue: boolean = ionValue.booleanValue(); return boolValue; }) ); }
Python
def update_and_query_ion_bool(txn): # QLDB can take in a Python bool a_bool = True # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleBool = ?", a_bool) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleBool FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python bool is a child class of Python bool a_bool = ion_value # example_bool is now the value fetched from QLDB return a_bool example_bool = driver.execute_lambda(lambda txn: update_and_query_ion_bool(txn))

Int

The following code examples show how to process the Ion integer type.

Java
// Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); int exampleInt = driver.execute((txn) -> { // Transforming a Java int to Ion int aInt = 256; IonValue ionInt = ionSystem.newInt(aInt); // Insertion into QLDB txn.execute("UPDATE ExampleTable SET ExampleInt = ?", ionInt); // Fetching from QLDB Result result = txn.execute("SELECT VALUE ExampleInt from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Transforming Ion to a Java int // Cast IonValue to IonInt first aInt = ((IonInt)ionValue).intValue(); } // exampleInt is now the value fetched from QLDB return aInt; });
.NET
using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; ... IValueFactory valueFactory = new ValueFactory(); // Transforming a C# int to Ion. int nativeInt = 256; IIonValue ionInt = valueFactory.NewInt(nativeInt); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleInt = ?", ionInt); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleInt from ExampleTable"); }); int? retrievedInt = null; // Assume there is only one document in ExampleTable. await foreach (IIonValue ionValue in selectResult) { // Transforming Ion to a C# int. retrievedInt = ionValue.IntValue; }
Note

To convert to synchronous code, remove the await and async keywords, and change the IAsyncResult type to IResult.

Go
exampleInt, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aInt := 256 // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleInt = ?", aInt) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleInt FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { var decodedResult int err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleInt is now the value fetched from QLDB return decodedResult, nil } return nil, result.Err() })
Node.js
async function queryIonInt(driver: QldbDriver): Promise<number> { return (driver.executeLambda(async (txn: TransactionExecutor) => { // Updating QLDB await txn.execute("UPDATE ExampleTable SET ExampleInt = ?", 256); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT VALUE ExampleInt FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // Transforming Ion to a TypeScript Number const intValue: number = ionValue.numberValue(); return intValue; }) ); }
Python
def update_and_query_ion_int(txn): # QLDB can take in a Python int a_int = 256 # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleInt = ?", a_int) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleInt FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python int is a child class of Python int a_int = ion_value # example_int is now the value fetched from QLDB return a_int example_int = driver.execute_lambda(lambda txn: update_and_query_ion_int(txn))

Float

The following code examples show how to process the Ion float type.

Java
// Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); float exampleFloat = driver.execute((txn) -> { // Transforming a Java float to Ion float aFloat = 256; IonValue ionFloat = ionSystem.newFloat(aFloat); // Insertion into QLDB txn.execute("UPDATE ExampleTable SET ExampleFloat = ?", ionFloat); // Fetching from QLDB Result result = txn.execute("SELECT VALUE ExampleFloat from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Transforming Ion to a Java float // Cast IonValue to IonFloat first aFloat = ((IonFloat)ionValue).floatValue(); } // exampleFloat is now the value fetched from QLDB return aFloat; });
.NET

Using C# float

using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; ... IValueFactory valueFactory = new ValueFactory(); // Transforming a C# float to Ion. float nativeFloat = 256; IIonValue ionFloat = valueFactory.NewFloat(nativeFloat); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleFloat = ?", ionFloat); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleFloat from ExampleTable"); }); float? retrievedFloat = null; // Assume there is only one document in ExampleTable. await foreach (IIonValue ionValue in selectResult) { // Transforming Ion to a C# float. We cast ionValue.DoubleValue to a float // but be cautious, this is a down-cast and can lose precision. retrievedFloat = (float)ionValue.DoubleValue; }
Note

To convert to synchronous code, remove the await and async keywords, and change the IAsyncResult type to IResult.

Using C# double

using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; ... IValueFactory valueFactory = new ValueFactory(); // Transforming a C# double to Ion. double nativeDouble = 256; IIonValue ionFloat = valueFactory.NewFloat(nativeDouble); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleFloat = ?", ionFloat); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleFloat from ExampleTable"); }); double? retrievedDouble = null; // Assume there is only one document in ExampleTable. await foreach (IIonValue ionValue in selectResult) { // Transforming Ion to a C# double. retrievedDouble = ionValue.DoubleValue; }
Note

To convert to synchronous code, remove the await and async keywords, and change the IAsyncResult type to IResult.

Go
exampleFloat, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aFloat := float32(256) // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleFloat = ?", aFloat) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleFloat FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { // float64 would work as well var decodedResult float32 err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleFloat is now the value fetched from QLDB return decodedResult, nil } return nil, result.Err() })
Node.js
async function queryIonFloat(driver: QldbDriver): Promise<number> { return (driver.executeLambda(async (txn: TransactionExecutor) => { // Updating QLDB await txn.execute("UPDATE ExampleTable SET ExampleFloat = ?", 25.6); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT VALUE ExampleFloat FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // Transforming Ion to a TypeScript Number const floatValue: number = ionValue.numberValue(); return floatValue; }) ); }
Python
def update_and_query_ion_float(txn): # QLDB can take in a Python float a_float = float(256) # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleFloat = ?", a_float) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleFloat FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python float is a child class of Python float a_float = ion_value # example_float is now the value fetched from QLDB return a_float example_float = driver.execute_lambda(lambda txn: update_and_query_ion_float(txn))

Decimal

The following code examples show how to process the Ion decimal type.

Java
// Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); double exampleDouble = driver.execute((txn) -> { // Transforming a Java double to Ion double aDouble = 256; IonValue ionDecimal = ionSystem.newDecimal(aDouble); // Insertion into QLDB txn.execute("UPDATE ExampleTable SET ExampleDecimal = ?", ionDecimal); // Fetching from QLDB Result result = txn.execute("SELECT VALUE ExampleDecimal from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Transforming Ion to a Java double // Cast IonValue to IonDecimal first aDouble = ((IonDecimal)ionValue).doubleValue(); } // exampleDouble is now the value fetched from QLDB return aDouble; });
.NET
using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; ... IValueFactory valueFactory = new ValueFactory(); // Transforming a C# decimal to Ion. decimal nativeDecimal = 256.8723m; IIonValue ionDecimal = valueFactory.NewDecimal(nativeDecimal); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleDecimal = ?", ionDecimal); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleDecimal from ExampleTable"); }); decimal? retrievedDecimal = null; // Assume there is only one document in ExampleTable. await foreach (IIonValue ionValue in selectResult) { // Transforming Ion to a C# decimal. retrievedDecimal = ionValue.DecimalValue; }
Note

To convert to synchronous code, remove the await and async keywords, and change the IAsyncResult type to IResult.

Go
exampleDecimal, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aDecimal, err := ion.ParseDecimal("256") if err != nil { return nil, err } // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleDecimal = ?", aDecimal) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleDecimal FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { var decodedResult ion.Decimal err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleDecimal is now the value fetched from QLDB return decodedResult, nil } return nil, result.Err() })
Node.js
async function queryIonDecimal(driver: QldbDriver): Promise<Decimal> { return (driver.executeLambda(async (txn: TransactionExecutor) => { // Creating a Decimal value. Decimal is an Ion Type with high precision let ionDecimal: Decimal = dom.load("2.5d-6").decimalValue(); // Updating QLDB await txn.execute("UPDATE ExampleTable SET ExampleDecimal = ?", ionDecimal); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT VALUE ExampleDecimal FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // Get the Ion Decimal ionDecimal = ionValue.decimalValue(); return ionDecimal; }) ); }
Note

You can also use ionValue.numberValue() to transform an Ion decimal to a JavaScript number. Using ionValue.numberValue() has better performance, but it's less precise.

Python
def update_and_query_ion_decimal(txn): # QLDB can take in a Python decimal a_decimal = Decimal(256) # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleDecimal = ?", a_decimal) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleDecimal FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python decimal is a child class of Python decimal a_decimal = ion_value # example_decimal is now the value fetched from QLDB return a_decimal example_decimal = driver.execute_lambda(lambda txn: update_and_query_ion_decimal(txn))

Timestamp

The following code examples show how to process the Ion timestamp type.

Java
// Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); Date exampleDate = driver.execute((txn) -> { // Transforming a Java Date to Ion Date aDate = new Date(); IonValue ionTimestamp = ionSystem.newUtcTimestamp(aDate); // Insertion into QLDB txn.execute("UPDATE ExampleTable SET ExampleTimestamp = ?", ionTimestamp); // Fetching from QLDB Result result = txn.execute("SELECT VALUE ExampleTimestamp from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Transforming Ion to a Java Date // Cast IonValue to IonTimestamp first aDate = ((IonTimestamp)ionValue).dateValue(); } // exampleDate is now the value fetched from QLDB return aDate; });
.NET
using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; using Amazon.IonDotnet; ... IValueFactory valueFactory = new ValueFactory(); // Convert C# native DateTime to Ion. DateTime nativeDateTime = DateTime.Now; // First convert it to a timestamp object from Ion. Timestamp timestamp = new Timestamp(nativeDateTime); // Then convert to Ion timestamp. IIonValue ionTimestamp = valueFactory.NewTimestamp(timestamp); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleTimestamp = ?", ionTimestamp); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleTimestamp from ExampleTable"); }); DateTime? retrievedDateTime = null; // Assume there is only one document in ExampleTable. await foreach (IIonValue ionValue in selectResult) { // Transforming Ion to a C# DateTime. retrievedDateTime = ionValue.TimestampValue.DateTimeValue; }
Note

To convert to synchronous code, remove the await and async keywords, and change the IAsyncResult type to IResult.

Go
exampleTimestamp, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aTimestamp := time.Date(2006, time.May, 20, 12, 30, 0, 0, time.UTC) if err != nil { return nil, err } // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleTimestamp = ?", aTimestamp) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleTimestamp FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { var decodedResult ion.Timestamp err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleTimestamp is now the value fetched from QLDB return decodedResult.GetDateTime(), nil } return nil, result.Err() })
Node.js
async function queryIonTimestamp(driver: QldbDriver): Promise<Date> { return (driver.executeLambda(async (txn: TransactionExecutor) => { let exampleDateTime: Date = new Date(Date.now()); // Updating QLDB await txn.execute("UPDATE ExampleTable SET ExampleTimestamp = ?", exampleDateTime); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT VALUE ExampleTimestamp FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // Transforming Ion to a TypeScript Date exampleDateTime = ionValue.timestampValue().getDate(); return exampleDateTime; }) ); }
Python
def update_and_query_ion_timestamp(txn): # QLDB can take in a Python timestamp a_datetime = datetime.now() # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleTimestamp = ?", a_datetime) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleTimestamp FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python timestamp is a child class of Python datetime a_timestamp = ion_value # example_timestamp is now the value fetched from QLDB return a_timestamp example_timestamp = driver.execute_lambda(lambda txn: update_and_query_ion_timestamp(txn))

String

The following code examples show how to process the Ion string type.

Java
// Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); String exampleString = driver.execute((txn) -> { // Transforming a Java String to Ion String aString = "Hello world!"; IonValue ionString = ionSystem.newString(aString); // Insertion into QLDB txn.execute("UPDATE ExampleTable SET ExampleString = ?", ionString); // Fetching from QLDB Result result = txn.execute("SELECT VALUE ExampleString from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Transforming Ion to a Java String // Cast IonValue to IonString first aString = ((IonString)ionValue).stringValue(); } // exampleString is now the value fetched from QLDB return aString; });
.NET
using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; ... IValueFactory valueFactory = new ValueFactory(); // Convert C# string to Ion. String nativeString = "Hello world!"; IIonValue ionString = valueFactory.NewString(nativeString); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleString = ?", ionString); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleString from ExampleTable"); }); String retrievedString = null; // Assume there is only one document in ExampleTable. await foreach (IIonValue ionValue in selectResult) { // Transforming Ion to a C# string. retrievedString = ionValue.StringValue; }
Note

To convert to synchronous code, remove the await and async keywords, and change the IAsyncResult type to IResult.

Go
exampleString, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aString := "Hello World!" // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleString = ?", aString) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleString FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { var decodedResult string err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleString is now the value fetched from QLDB return decodedResult, nil } return nil, result.Err() })
Node.js
async function queryIonString(driver: QldbDriver): Promise<string> { return (driver.executeLambda(async (txn: TransactionExecutor) => { // Updating QLDB await txn.execute("UPDATE ExampleTable SET ExampleString = ?", "Hello World!"); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT VALUE ExampleString FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // Transforming Ion to a TypeScript String const stringValue: string = ionValue.stringValue(); return stringValue; }) ); }
Python
def update_and_query_ion_string(txn): # QLDB can take in a Python string a_string = "Hello world!" # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleString = ?", a_string) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleString FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python string is a child class of Python string a_string = ion_value # example_string is now the value fetched from QLDB return a_string example_string = driver.execute_lambda(lambda txn: update_and_query_ion_string(txn))

Blob

The following code examples show how to process the Ion blob type.

Java
// Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); byte[] exampleBytes = driver.execute((txn) -> { // Transforming a Java byte array to Ion // Transform any arbitrary data to a byte array to store in QLDB String aString = "Hello world!"; byte[] aByteArray = aString.getBytes(); IonValue ionBlob = ionSystem.newBlob(aByteArray); // Insertion into QLDB txn.execute("UPDATE ExampleTable SET ExampleBlob = ?", ionBlob); // Fetching from QLDB Result result = txn.execute("SELECT VALUE ExampleBlob from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Transforming Ion to a Java byte array // Cast IonValue to IonBlob first aByteArray = ((IonBlob)ionValue).getBytes(); } // exampleBytes is now the value fetched from QLDB return aByteArray; });
.NET
using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; using System.Text; ... IValueFactory valueFactory = new ValueFactory(); // Transform any arbitrary data to a byte array to store in QLDB. string nativeString = "Hello world!"; byte[] nativeByteArray = Encoding.UTF8.GetBytes(nativeString); // Transforming a C# byte array to Ion. IIonValue ionBlob = valueFactory.NewBlob(nativeByteArray); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleBlob = ?", ionBlob); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleBlob from ExampleTable"); }); byte[] retrievedByteArray = null; // Assume there is only one document in ExampleTable. await foreach (IIonValue ionValue in selectResult) { // Transforming Ion to a C# byte array. retrievedByteArray = ionValue.Bytes().ToArray(); }
Note

To convert to synchronous code, remove the await and async keywords, and change the IAsyncResult type to IResult.

Go
exampleBlob, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aBlob := []byte("Hello World!") // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleBlob = ?", aBlob) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleBlob FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { var decodedResult []byte err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleBlob is now the value fetched from QLDB return decodedResult, nil } return nil, result.Err() })
Node.js
async function queryIonBlob(driver: QldbDriver): Promise<Uint8Array> { return (driver.executeLambda(async (txn: TransactionExecutor) => { const enc = new TextEncoder(); let blobValue: Uint8Array = enc.encode("Hello World!"); // Updating QLDB await txn.execute("UPDATE ExampleTable SET ExampleBlob = ?", blobValue); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT VALUE ExampleBlob FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // Transforming Ion to TypeScript Uint8Array blobValue = ionValue.uInt8ArrayValue(); return blobValue; }) ); }
Python
def update_and_query_ion_blob(txn): # QLDB can take in a Python byte array a_string = "Hello world!" a_byte_array = str.encode(a_string) # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleBlob = ?", a_byte_array) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleBlob FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python blob is a child class of Python byte array a_blob = ion_value # example_blob is now the value fetched from QLDB return a_blob example_blob = driver.execute_lambda(lambda txn: update_and_query_ion_blob(txn))

List

The following code examples show how to process the Ion list type.

Java
// Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); List<Integer> exampleList = driver.execute((txn) -> { // Transforming a Java List to Ion List<Integer> aList = new ArrayList<>(); // Add 5 Integers to the List for the sake of example for (int i = 0; i < 5; i++) { aList.add(i); } // Create an empty Ion List IonList ionList = ionSystem.newEmptyList(); // Add the 5 Integers to the Ion List for (Integer i : aList) { // Convert each Integer to Ion ints first to add it to the Ion List ionList.add(ionSystem.newInt(i)); } // Insertion into QLDB txn.execute("UPDATE ExampleTable SET ExampleList = ?", (IonValue) ionList); // Fetching from QLDB Result result = txn.execute("SELECT VALUE ExampleList from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Iterate through the Ion List to map it to a Java List List<Integer> intList = new ArrayList<>(); for (IonValue ionInt : (IonList)ionValue) { // Convert the 5 Ion ints to Java Integers intList.add(((IonInt)ionInt).intValue()); } aList = intList; } // exampleList is now the value fetched from QLDB return aList; });
.NET
using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; using System.Collections.Generic; ... IValueFactory valueFactory = new ValueFactory(); // Transforming a C# list to Ion. IIonValue ionList = valueFactory.NewEmptyList(); foreach (int i in new List<int> {0, 1, 2, 3, 4}) { // Convert to Ion int and add to Ion list. ionList.Add(valueFactory.NewInt(i)); } IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleList = ?", ionList); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleList from ExampleTable"); }); List<int> retrievedList = new List<int>(); await foreach (IIonValue ionValue in selectResult) { // Iterate through the Ion List to map it to a C# list. foreach (IIonValue ionInt in ionValue) { retrievedList.Add(ionInt.IntValue); } }
Note

To convert to synchronous code, remove the await and async keywords, and change the IAsyncResult type to IResult.

Go
exampleList, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aList := []int{1, 2, 3, 4, 5} // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleList = ?", aList) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleList FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { var decodedResult []int err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleList is now the value fetched from QLDB return decodedResult, nil } return nil, result.Err() })
Node.js
async function queryIonList(driver: QldbDriver): Promise<number[]> { return (driver.executeLambda(async (txn: TransactionExecutor) => { let listOfNumbers: number[] = [1, 2, 3, 4, 5]; // Updating QLDB await txn.execute("UPDATE ExampleTable SET ExampleList = ?", listOfNumbers); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT VALUE ExampleList FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // Get Ion List const ionList: dom.Value[] = ionValue.elements(); // Iterate through the Ion List to map it to a JavaScript Array let intList: number[] = []; ionList.forEach(item => { // Transforming Ion to a TypeScript Number const intValue: number = item.numberValue(); intList.push(intValue); }); listOfNumbers = intList; return listOfNumbers; }) ); }
Python
def update_and_query_ion_list(txn): # QLDB can take in a Python list a_list = list() for i in range(0, 5): a_list.append(i) # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleList = ?", a_list) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleList FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python blob is a child class of Python list a_list = ion_value # example_list is now the value fetched from QLDB return a_list example_list = driver.execute_lambda(lambda txn: update_and_query_ion_list(txn))

Struct

In QLDB, struct data types are particularly unique from other Ion types. Top-level documents that you insert into a table must be of the struct type. A document field can also store a nested struct.

For simplicity, the following examples define a document that has the ExampleString and ExampleInt fields only.

Java
class ExampleStruct { public String exampleString; public int exampleInt; public ExampleStruct(String exampleString, int exampleInt) { this.exampleString = exampleString; this.exampleInt = exampleInt; } } // Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); ExampleStruct examplePojo = driver.execute((txn) -> { // Transforming a POJO to Ion ExampleStruct aPojo = new ExampleStruct("Hello world!", 256); // Create an empty Ion struct IonStruct ionStruct = ionSystem.newEmptyStruct(); // Map the fields of the POJO to Ion values and put them in the Ion struct ionStruct.add("ExampleString", ionSystem.newString(aPojo.exampleString)); ionStruct.add("ExampleInt", ionSystem.newInt(aPojo.exampleInt)); // Insertion into QLDB txn.execute("INSERT INTO ExampleTable ?", ionStruct); // Fetching from QLDB Result result = txn.execute("SELECT * from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Map the fields of the Ion struct to Java values and construct a new POJO ionStruct = (IonStruct)ionValue; IonString exampleString = (IonString)ionStruct.get("ExampleString"); IonInt exampleInt = (IonInt)ionStruct.get("ExampleInt"); aPojo = new ExampleStruct(exampleString.stringValue(), exampleInt.intValue()); } // examplePojo is now the document fetched from QLDB return aPojo; });

Alternatively, you can use the Jackson library to map data types to and from Ion. The library supports the other Ion data types, but this example focuses on the struct type.

class ExampleStruct { public String exampleString; public int exampleInt; @JsonCreator public ExampleStruct(@JsonProperty("ExampleString") String exampleString, @JsonProperty("ExampleInt") int exampleInt) { this.exampleString = exampleString; this.exampleInt = exampleInt; } @JsonProperty("ExampleString") public String getExampleString() { return this.exampleString; } @JsonProperty("ExampleInt") public int getExampleInt() { return this.exampleInt; } } // Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); // Instantiate an IonObjectMapper from the Jackson library IonObjectMapper ionMapper = new IonValueMapper(ionSystem); ExampleStruct examplePojo = driver.execute((txn) -> { // Transforming a POJO to Ion ExampleStruct aPojo = new ExampleStruct("Hello world!", 256); IonValue ionStruct; try { // Use the mapper to convert Java objects into Ion ionStruct = ionMapper.writeValueAsIonValue(aPojo); } catch (IOException e) { // Wrap the exception and throw it for the sake of simplicity in this example throw new RuntimeException(e); } // Insertion into QLDB txn.execute("INSERT INTO ExampleTable ?", ionStruct); // Fetching from QLDB Result result = txn.execute("SELECT * from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Use the mapper to convert Ion to Java objects try { aPojo = ionMapper.readValue(ionValue, ExampleStruct.class); } catch (IOException e) { // Wrap the exception and throw it for the sake of simplicity in this example throw new RuntimeException(e); } } // examplePojo is now the document fetched from QLDB return aPojo; });
.NET
using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; ... IValueFactory valueFactory = new ValueFactory(); // Creating Ion struct. IIonValue ionStruct = valueFactory.NewEmptyStruct(); ionStruct.SetField("ExampleString", valueFactory.NewString("Hello world!")); ionStruct.SetField("ExampleInt", valueFactory.NewInt(256)); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleStruct = ?", ionStruct); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleStruct from ExampleTable"); }); string retrievedString = null; int? retrievedInt = null; await foreach (IIonValue ionValue in selectResult) { retrievedString = ionValue.GetField("ExampleString").StringValue; retrievedInt = ionValue.GetField("ExampleInt").IntValue; }
Note

To convert to synchronous code, remove the await and async keywords, and change the IAsyncResult type to IResult.

Go
exampleStruct, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aStruct := map[string]interface{} { "ExampleString": "Hello World!", "ExampleInt": 256, } // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleStruct = ?", aStruct) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleStruct FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { var decodedResult map[string]interface{} err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleStruct is now the value fetched from QLDB return decodedResult, nil } return nil, result.Err() })
Node.js
async function queryIonStruct(driver: QldbDriver): Promise<any> { let exampleStruct: any = {stringValue: "Hello World!", intValue: 256}; return (driver.executeLambda(async (txn: TransactionExecutor) => { // Inserting into QLDB await txn.execute("INSERT INTO ExampleTable ?", exampleStruct); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT * FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // We can get all the keys of Ion struct and their associated values const ionFieldNames: string[] = ionValue.fieldNames(); // Getting key and value of Ion struct to TypeScript String and Number const nativeStringVal: string = ionValue.get(ionFieldNames[0]).stringValue(); const nativeIntVal: number = ionValue.get(ionFieldNames[1]).numberValue(); // Alternatively, we can access to Ion struct fields, using their literal field names: // const nativeStringVal = ionValue.get("stringValue").stringValue(); // const nativeIntVal = ionValue.get("intValue").numberValue(); exampleStruct = {[ionFieldNames[0]]: nativeStringVal, [ionFieldNames[1]]: nativeIntVal}; return exampleStruct; }) ); }
Python
def update_and_query_ion_struct(txn): # QLDB can take in a Python struct a_struct = {"ExampleString": "Hello world!", "ExampleInt": 256} # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleStruct = ?", a_struct) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleStruct FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python struct is a child class of Python struct a_struct = ion_value # example_struct is now the value fetched from QLDB return a_struct example_struct = driver.execute_lambda(lambda txn: update_and_query_ion_struct(txn))

Null values and dynamic types

QLDB supports open content and doesn't enforce schema or data type definitions for document fields. You can also store Ion null values in a QLDB document. All of the prior examples assume that each returned data type is known and is not null. The following examples show how to work with Ion when the data type isn't known or is possibly null.

Java
// Empty variables String exampleString = null; Integer exampleInt = null; // Assume ionValue is some queried data from QLDB IonValue ionValue = null; // Check the value type and assign it to the variable if it is not null if (ionValue.getType() == IonType.STRING) { if (ionValue.isNullValue()) { exampleString = null; } else { exampleString = ((IonString)ionValue).stringValue(); } } else if (ionValue.getType() == IonType.INT) { if (ionValue.isNullValue()) { exampleInt = null; } else { exampleInt = ((IonInt)ionValue).intValue(); } }; // Creating null values IonSystem ionSystem = IonSystemBuilder.standard().build(); // A null value still has an Ion type IonString ionString; if (exampleString == null) { // Specifically a null string ionString = ionSystem.newNullString(); } else { ionString = ionSystem.newString(exampleString); } IonInt ionInt; if (exampleInt == null) { // Specifically a null int ionInt = ionSystem.newNullInt(); } else { ionInt = ionSystem.newInt(exampleInt); } // Special case regarding null! // There is a generic null type which has Ion type 'Null'. // The above null values still have the types 'String' and 'Int' IonValue specialNull = ionSystem.newNull(); if (specialNull.getType() == IonType.NULL) { // This is true! } if (specialNull.isNullValue()) { // This is also true! } if (specialNull.getType() == IonType.STRING || specialNull.getType() == IonType.INT) { // This is false! }
.NET
// Empty variables. string exampleString = null; int? exampleInt = null; // Assume ionValue is some queried data from QLDB. IIonValue ionValue; if (ionValue.Type() == IonType.String) { exampleString = ionValue.StringValue; } else if (ionValue.Type() == IonType.Int) { if (ionValue.IsNull) { exampleInt = null; } else { exampleInt = ionValue.IntValue; } }; // Creating null values. IValueFactory valueFactory = new ValueFactory(); // A null value still has an Ion type. IIonValue ionString = valueFactory.NewString(exampleString); IIonValue ionInt; if (exampleInt == null) { // Specifically a null int. ionInt = valueFactory.NewNullInt(); } else { ionInt = valueFactory.NewInt(exampleInt.Value); } // Special case regarding null! // There is a generic null type which has Ion type 'Null'. IIonValue specialNull = valueFactory.NewNull(); if (specialNull.Type() == IonType.Null) { // This is true! } if (specialNull.IsNull) { // This is also true! }
Go

Marshalling limitations

In Go, nil values don't retain their type when you marshal and then unmarshal them. A nil value marshals to Ion null, but Ion null unmarshals to a zero value rather than nil.

ionNull, err := ion.MarshalText(nil) // ionNull is set to ion null if err != nil { return } var result int err = ion.Unmarshal(ionNull, &result) // result unmarshals to 0 if err != nil { return }
Node.js
// Empty variables let exampleString: string; let exampleInt: number; // Assume ionValue is some queried data from QLDB // Check the value type and assign it to the variable if it is not null if (ionValue.getType() === IonTypes.STRING) { if (ionValue.isNull()) { exampleString = null; } else { exampleString = ionValue.stringValue(); } } else if (ionValue.getType() === IonTypes.INT) { if (ionValue.isNull()) { exampleInt = null; } else { exampleInt = ionValue.numberValue(); } } // Creating null values if (exampleString === null) { ionString = dom.load('null.string'); } else { ionString = dom.load.of(exampleString); } if (exampleInt === null) { ionInt = dom.load('null.int'); } else { ionInt = dom.load.of(exampleInt); } // Special case regarding null! // There is a generic null type which has Ion type 'Null'. // The above null values still have the types 'String' and 'Int' specialNull: dom.Value = dom.load("null.null"); if (specialNull.getType() === IonType.NULL) { // This is true! } if (specialNull.getType() === IonType.STRING || specialNull.getType() === IonType.INT) { // This is false! }
Python
# Empty variables example_string = None example_int = None # Assume ion_value is some queried data from QLDB # Check the value type and assign it to the variable if it is not null if ion_value.ion_type == IonType.STRING: if isinstance(ion_value, IonPyNull): example_string = None else: example_string = ion_value elif ion_value.ion_type == IonType.INT: if isinstance(ion_value, IonPyNull): example_int = None else: example_int = ion_value # Creating Ion null values if example_string is None: # Specifically a null string ion_string = loads("null.string") else: # QLDB can take in Python string ion_string = example_string if example_int is None: # Specifically a null int ion_int = loads("null.int") else: # QLDB can take in Python int ion_int = example_int # Special case regarding null! # There is a generic null type which has Ion type 'Null'. # The above null values still have the types 'String' and 'Int' special_null = loads("null.null") if special_null.ion_type == IonType.NULL: # This is true! if special_null.ion_type == IonType.STRING or special_null.ion_type == IonType.INT: # This is false!

Down-converting to JSON

If your application requires JSON compatibility, you can down-convert Amazon Ion data to JSON. However, converting Ion to JSON is lossy in certain cases where your data leverages the rich Ion types that don't exist in JSON.

For details about Ion to JSON conversion rules, see Down-converting to JSON in the Amazon Ion Cookbook.