Amazon QLDB での Amazon Ion のデータ型の操作 - Amazon Quantum Ledger Database (Amazon QLDB)

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Amazon QLDB での Amazon Ion のデータ型の操作

Amazon QLDB は、Amazon Ion 形式でデータを格納します。QLDB でデータを操作するには、Ion ライブラリサポートされているプログラミング言語の依存関係として。

このセクションでは、ネイティブ型から同等のイオン型にデータを変換する方法と、その逆の方法を学びます。このリファレンスガイドでは、QLDB ドライバを使用して QLDB レジャー内の Ion データを処理するコード例を示します。Java、.NET (C#)、Go、Node.js () のコード例が含まれています。TypeScript)、Python。

前提条件

次のコード例では、という名前のテーブルを持つアクティブレジャーに接続された QLDB ドライバインスタンスがあることを前提としています。ExampleTable。テーブルには、次の 8 つのフィールドを持つ既存のドキュメントが 1 つ含まれています。

  • ExampleBool

  • ExampleInt

  • ExampleFloat

  • ExampleDecimal

  • ExampleTimestamp

  • ExampleString

  • ExampleBlob

  • ExampleList

注記

この参照の目的で、各フィールドに格納されている型がその名前と一致すると仮定します。実際には、QLDB はドキュメントフィールドのスキーマまたはデータ型の定義を強制しません。

Bool

次のコード例は、Ion ブール型の処理方法を示しています。

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; }
注記

同期コードに変換するには、awaitそしてasyncキーワードを変更して、IAsyncResult次のように入力します。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

次のコード例は、Ion 整数型の処理方法を示しています。

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; }
注記

同期コードに変換するには、awaitそしてasyncキーワードを変更して、IAsyncResult次のように入力します。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))

浮動小数点

次のコード例は、Ion 浮動小数点型の処理方法を示しています。

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

C# float の使用

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; }
注記

同期コードに変換するには、awaitそしてasyncキーワードを変更して、IAsyncResult次のように入力します。IResult

C# ダブルの使用

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; }
注記

同期コードに変換するには、awaitそしてasyncキーワードを変更して、IAsyncResult次のように入力します。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))

10 進数

次のコード例は、Ion 10 進数の処理方法を示しています。

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; }
注記

同期コードに変換するには、awaitそしてasyncキーワードを変更して、IAsyncResult次のように入力します。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; }) ); }
注記

また、ionValue.numberValue()イオン10進数をJavaScript番号。を使用するionValue.numberValue()パフォーマンスは優れていますが、精度は低くなります。

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))

タイムスタンプ

次のコード例は、Ion タイムスタンプタイプの処理方法を示しています。

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; }
注記

同期コードに変換するには、awaitそしてasyncキーワードを変更して、IAsyncResult次のように入力します。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))

文字列

次のコード例は、Ion 文字列タイプの処理方法を示しています。

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; }
注記

同期コードに変換するには、awaitそしてasyncキーワードを変更して、IAsyncResult次のように入力します。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

次のコード例は、Ion ブロブタイプの処理方法を示しています。

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(); }
注記

同期コードに変換するには、awaitそしてasyncキーワードを変更して、IAsyncResult次のように入力します。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))

リスト

次のコード例は、Ion リストタイプの処理方法を示しています。

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); } }
注記

同期コードに変換するには、awaitそしてasyncキーワードを変更して、IAsyncResult次のように入力します。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))

構造体

QLDB ではstructデータ型は、他のイオンタイプとは特に一意です。表に挿入する最上位レベルのドキュメントは、structタイプを作成することができます。ドキュメントフィールドには、ネストされたものを格納することもできます。struct

簡単にするために、次の例は、ExampleStringそしてExampleIntフィールドのみ。

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; });

を使用することもできます。JacksonIon との間でデータ型をマッピングします。ライブラリは他の Ion データ型をサポートしていますが、この例では、structタイプを作成することができます。

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

を使用するAmazon.qldb.driver.SerializationIon との間でネイティブ C# データ型をマッピングするためのライブラリ。ライブラリは他の Ion データ型をサポートしていますが、この例では、structタイプを作成することができます。

using Amazon.QLDB.Driver.Generic; using Amazon.QLDB.Driver.Serialization; ... IAsyncQldbDriver driver = AsyncQldbDriver.Builder() .WithLedger("vehicle-registration") // Add Serialization library .WithSerializer(new ObjectSerializer()) .Build(); // Creating a C# POCO. ExampleStruct exampleStruct = new ExampleStruct { ExampleString = "Hello world!", ExampleInt = 256 }; IAsyncResult<ExampleStruct> selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute(txn.Query<Document>("UPDATE ExampleTable SET ExampleStruct = ?", exampleStruct)); // Fetching from QLDB. return await txn.Execute(txn.Query<ExampleStruct>("SELECT VALUE ExampleStruct from ExampleTable")); }); await foreach (ExampleStruct row in selectResult) { Console.WriteLine(row.ExampleString); Console.WriteLine(row.ExampleInt); }
注記

同期コードに変換するには、awaitそしてasyncキーワードを変更して、IAsyncResult次のように入力します。IResult

を使用することもできます。Amazon。IonDotnet.BuilderIon データ型を処理するためのライブラリ。

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; }
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 値と動的型

QLDB はオープンコンテンツをサポートし、ドキュメントフィールドのスキーマやデータ型の定義を強制しません。イオンヌル値を QLDB ドキュメントに保存することもできます。前の例はすべて、返される各データ型が既知であり、null ではないと仮定しています。次の例は、Ion のデータ型が不明の場合や、NULL の場合の操作方法を示しています。

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

マーシャリングの制限

Go ではnilマーシャリングしてからアンマーシャリングしても、値は型を保持しません。あるnil値はイオンヌルにマーシャリングされますが、イオンヌルではなくゼロ値にアンマーシャリングします。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!

JSON へのダウン変換

アプリケーションで JSON 互換性が必要な場合は、Amazon Ion データを JSON にダウン変換できます。ただし、データが JSON に存在しないリッチイオンタイプを利用している特定のケースでは、Ion を JSON に変換することは損失がちです。

Ion から JSON への変換ルールの詳細については、を参照してください。JSON へのダウン変換Amazon Ion クックブック