Amazon DynamoDB
API Reference (API Version 2012-08-10)
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PutItem

Creates a new item, or replaces an old item with a new item. If an item that has the same primary key as the new item already exists in the specified table, the new item completely replaces the existing item. You can perform a conditional put operation (add a new item if one with the specified primary key doesn't exist), or replace an existing item if it has certain attribute values.

In addition to putting an item, you can also return the item's attribute values in the same operation, using the ReturnValues parameter.

When you add an item, the primary key attribute(s) are the only required attributes. Attribute values cannot be null. String and Binary type attributes must have lengths greater than zero. Set type attributes cannot be empty. Requests with empty values will be rejected with a ValidationException exception.

You can request that PutItem return either a copy of the original item (before the update) or a copy of the updated item (after the update). For more information, see the ReturnValues description below.

Note

To prevent a new item from replacing an existing item, use a conditional put operation with ComparisonOperator set to NULL for the primary key attribute, or attributes.

For more information about using this API, see Working with Items in the Amazon DynamoDB Developer Guide.

Request Syntax

{
    "ConditionExpression": "string",
    "ConditionalOperator": "string",
    "Expected": 
        {
            "string" :
                {
                    "AttributeValueList": [
                        {
                            "B": "blob",
                            "BOOL": "boolean",
                            "BS": [
                                "blob"
                            ],
                            "L": [
                                AttributeValue
                            ],
                            "M": 
                                {
                                    "string" :
                                        AttributeValue
                                },
                            "N": "string",
                            "NS": [
                                "string"
                            ],
                            "NULL": "boolean",
                            "S": "string",
                            "SS": [
                                "string"
                            ]
                        }
                    ],
                    "ComparisonOperator": "string",
                    "Exists": "boolean",
                    "Value": {
                        "B": "blob",
                        "BOOL": "boolean",
                        "BS": [
                            "blob"
                        ],
                        "L": [
                            AttributeValue
                        ],
                        "M": 
                            {
                                "string" :
                                    AttributeValue
                            },
                        "N": "string",
                        "NS": [
                            "string"
                        ],
                        "NULL": "boolean",
                        "S": "string",
                        "SS": [
                            "string"
                        ]
                    }
                }
        },
    "ExpressionAttributeNames": 
        {
            "string" :
                "string"
        },
    "ExpressionAttributeValues": 
        {
            "string" :
                {
                    "B": "blob",
                    "BOOL": "boolean",
                    "BS": [
                        "blob"
                    ],
                    "L": [
                        AttributeValue
                    ],
                    "M": 
                        {
                            "string" :
                                AttributeValue
                        },
                    "N": "string",
                    "NS": [
                        "string"
                    ],
                    "NULL": "boolean",
                    "S": "string",
                    "SS": [
                        "string"
                    ]
                }
        },
    "Item": 
        {
            "string" :
                {
                    "B": "blob",
                    "BOOL": "boolean",
                    "BS": [
                        "blob"
                    ],
                    "L": [
                        AttributeValue
                    ],
                    "M": 
                        {
                            "string" :
                                AttributeValue
                        },
                    "N": "string",
                    "NS": [
                        "string"
                    ],
                    "NULL": "boolean",
                    "S": "string",
                    "SS": [
                        "string"
                    ]
                }
        },
    "ReturnConsumedCapacity": "string",
    "ReturnItemCollectionMetrics": "string",
    "ReturnValues": "string",
    "TableName": "string"
}
			

Request Parameters

The request accepts the following data in JSON format.

Note

In the following list, the required parameters are described first.

Item

A map of attribute name/value pairs, one for each attribute. Only the primary key attributes are required; you can optionally provide other attribute name-value pairs for the item.

You must provide all of the attributes for the primary key. For example, with a hash type primary key, you only need to specify the hash attribute. For a hash-and-range type primary key, you must specify both the hash attribute and the range attribute.

If you specify any attributes that are part of an index key, then the data types for those attributes must match those of the schema in the table's attribute definition.

For more information about primary keys, see Primary Key in the Amazon DynamoDB Developer Guide.

Each element in the Item map is an AttributeValue object.

Type: String to AttributeValue object map

Required: Yes

TableName

The name of the table to contain the item.

Type: String

Length constraints: Minimum length of 3. Maximum length of 255.

Required: Yes

ConditionExpression

A condition that must be satisfied in order for a conditional PutItem operation to succeed.

An expression can contain any of the following:

  • Boolean functions: attribute_exists | attribute_not_exists | contains | begins_with

    These function names are case-sensitive.

  • Comparison operators: = | <> | < | > | <= | >= | BETWEEN | IN

  • Logical operators: AND | OR | NOT

For more information on condition expressions, go to Specifying Conditions in the Amazon DynamoDB Developer Guide.

Type: String

Required: No

ConditionalOperator

Important

There is a newer parameter available. Use ConditionExpression instead. Note that if you use ConditionalOperator and ConditionExpression at the same time, DynamoDB will return a ValidationException exception.

This parameter does not support lists or maps.

A logical operator to apply to the conditions in the Expected map:

  • AND - If all of the conditions evaluate to true, then the entire map evaluates to true.

  • OR - If at least one of the conditions evaluate to true, then the entire map evaluates to true.

If you omit ConditionalOperator, then AND is the default.

The operation will succeed only if the entire map evaluates to true.

Type: String

Valid Values: AND | OR

Required: No

Expected

Important

There is a newer parameter available. Use ConditionExpression instead. Note that if you use Expected and ConditionExpression at the same time, DynamoDB will return a ValidationException exception.

This parameter does not support lists or maps.

A map of attribute/condition pairs. Expected provides a conditional block for the PutItem operation.

Each element of Expected consists of an attribute name, a comparison operator, and one or more values. DynamoDB compares the attribute with the value(s) you supplied, using the comparison operator. For each Expected element, the result of the evaluation is either true or false.

If you specify more than one element in the Expected map, then by default all of the conditions must evaluate to true. In other words, the conditions are ANDed together. (You can use the ConditionalOperator parameter to OR the conditions instead. If you do this, then at least one of the conditions must evaluate to true, rather than all of them.)

If the Expected map evaluates to true, then the conditional operation succeeds; otherwise, it fails.

Expected contains the following:

  • AttributeValueList - One or more values to evaluate against the supplied attribute. The number of values in the list depends on the ComparisonOperator being used.

    For type Number, value comparisons are numeric.

    String value comparisons for greater than, equals, or less than are based on ASCII character code values. For example, a is greater than A, and aa is greater than B. For a list of code values, see http://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters.

    For type Binary, DynamoDB treats each byte of the binary data as unsigned when it compares binary values, for example when evaluating query expressions.

  • ComparisonOperator - A comparator for evaluating attributes in the AttributeValueList. When performing the comparison, DynamoDB uses strongly consistent reads.

    The following comparison operators are available:

    EQ | NE | LE | LT | GE | GT | NOT_NULL | NULL | CONTAINS | NOT_CONTAINS | BEGINS_WITH | IN | BETWEEN

    The following are descriptions of each comparison operator.

    • EQ : Equal. EQ is supported for all datatypes, including lists and maps.

      AttributeValueList can contain only one AttributeValue element of type String, Number, Binary, String Set, Number Set, or Binary Set. If an item contains an AttributeValue element of a different type than the one specified in the request, the value does not match. For example, {"S":"6"} does not equal {"N":"6"}. Also, {"N":"6"} does not equal {"NS":["6", "2", "1"]}.

    • NE : Not equal. NE is supported for all datatypes, including lists and maps.

      AttributeValueList can contain only one AttributeValue of type String, Number, Binary, String Set, Number Set, or Binary Set. If an item contains an AttributeValue of a different type than the one specified in the request, the value does not match. For example, {"S":"6"} does not equal {"N":"6"}. Also, {"N":"6"} does not equal {"NS":["6", "2", "1"]}.

    • LE : Less than or equal.

      AttributeValueList can contain only one AttributeValue element of type String, Number, or Binary (not a set type). If an item contains an AttributeValue element of a different type than the one specified in the request, the value does not match. For example, {"S":"6"} does not equal {"N":"6"}. Also, {"N":"6"} does not compare to {"NS":["6", "2", "1"]}.

    • LT : Less than.

      AttributeValueList can contain only one AttributeValue of type String, Number, or Binary (not a set type). If an item contains an AttributeValue element of a different type than the one specified in the request, the value does not match. For example, {"S":"6"} does not equal {"N":"6"}. Also, {"N":"6"} does not compare to {"NS":["6", "2", "1"]}.

    • GE : Greater than or equal.

      AttributeValueList can contain only one AttributeValue element of type String, Number, or Binary (not a set type). If an item contains an AttributeValue element of a different type than the one specified in the request, the value does not match. For example, {"S":"6"} does not equal {"N":"6"}. Also, {"N":"6"} does not compare to {"NS":["6", "2", "1"]}.

    • GT : Greater than.

      AttributeValueList can contain only one AttributeValue element of type String, Number, or Binary (not a set type). If an item contains an AttributeValue element of a different type than the one specified in the request, the value does not match. For example, {"S":"6"} does not equal {"N":"6"}. Also, {"N":"6"} does not compare to {"NS":["6", "2", "1"]}.

    • NOT_NULL : The attribute exists. NOT_NULL is supported for all datatypes, including lists and maps.

      Note

      This operator tests for the existence of an attribute, not its data type. If the data type of attribute "a" is null, and you evaluate it using NOT_NULL, the result is a Boolean true. This result is because the attribute "a" exists; its data type is not relevant to the NOT_NULL comparison operator.

    • NULL : The attribute does not exist. NULL is supported for all datatypes, including lists and maps.

      Note

      This operator tests for the nonexistence of an attribute, not its data type. If the data type of attribute "a" is null, and you evaluate it using NULL, the result is a Boolean false. This is because the attribute "a" exists; its data type is not relevant to the NULL comparison operator.

    • CONTAINS : Checks for a subsequence, or value in a set.

      AttributeValueList can contain only one AttributeValue element of type String, Number, or Binary (not a set type). If the target attribute of the comparison is of type String, then the operator checks for a substring match. If the target attribute of the comparison is of type Binary, then the operator looks for a subsequence of the target that matches the input. If the target attribute of the comparison is a set ("SS", "NS", or "BS"), then the operator evaluates to true if it finds an exact match with any member of the set.

      CONTAINS is supported for lists: When evaluating "a CONTAINS b", "a" can be a list; however, "b" cannot be a set, a map, or a list.

    • NOT_CONTAINS : Checks for absence of a subsequence, or absence of a value in a set.

      AttributeValueList can contain only one AttributeValue element of type String, Number, or Binary (not a set type). If the target attribute of the comparison is a String, then the operator checks for the absence of a substring match. If the target attribute of the comparison is Binary, then the operator checks for the absence of a subsequence of the target that matches the input. If the target attribute of the comparison is a set ("SS", "NS", or "BS"), then the operator evaluates to true if it does not find an exact match with any member of the set.

      NOT_CONTAINS is supported for lists: When evaluating "a NOT CONTAINS b", "a" can be a list; however, "b" cannot be a set, a map, or a list.

    • BEGINS_WITH : Checks for a prefix.

      AttributeValueList can contain only one AttributeValue of type String or Binary (not a Number or a set type). The target attribute of the comparison must be of type String or Binary (not a Number or a set type).

    • IN : Checks for matching elements within two sets.

      AttributeValueList can contain one or more AttributeValue elements of type String, Number, or Binary (not a set type). These attributes are compared against an existing set type attribute of an item. If any elements of the input set are present in the item attribute, the expression evaluates to true.

    • BETWEEN : Greater than or equal to the first value, and less than or equal to the second value.

      AttributeValueList must contain two AttributeValue elements of the same type, either String, Number, or Binary (not a set type). A target attribute matches if the target value is greater than, or equal to, the first element and less than, or equal to, the second element. If an item contains an AttributeValue element of a different type than the one specified in the request, the value does not match. For example, {"S":"6"} does not compare to {"N":"6"}. Also, {"N":"6"} does not compare to {"NS":["6", "2", "1"]}

For usage examples of AttributeValueList and ComparisonOperator, see Legacy Conditional Parameters in the Amazon DynamoDB Developer Guide.

For backward compatibility with previous DynamoDB releases, the following parameters can be used instead of AttributeValueList and ComparisonOperator:

  • Value - A value for DynamoDB to compare with an attribute.

  • Exists - A Boolean value that causes DynamoDB to evaluate the value before attempting the conditional operation:

    • If Exists is true, DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the condition evaluates to true; otherwise the condition evaluate to false.

    • If Exists is false, DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the condition evaluates to true. If the value is found, despite the assumption that it does not exist, the condition evaluates to false.

The Value and Exists parameters are incompatible with AttributeValueList and ComparisonOperator. Note that if you use both sets of parameters at once, DynamoDB will return a ValidationException exception.

Type: String to ExpectedAttributeValue object map

Required: No

ExpressionAttributeNames

One or more substitution tokens for simplifying complex expressions. The following are some use cases for using ExpressionAttributeNames:

  • To shorten an attribute name that is very long or unwieldy in an expression.

  • To create a placeholder for repeating occurrences of an attribute name in an expression.

  • To prevent special characters in an attribute name from being misinterpreted in an expression.

Use the # character in an expression to dereference an attribute name. For example, consider the following expression:

  • order.customerInfo.LastName = "Smith" OR order.customerInfo.LastName = "Jones"

Now suppose that you specified the following for ExpressionAttributeNames:

  • {"#name":"order.customerInfo.LastName"}

The expression can now be simplified as follows:

  • #name = "Smith" OR #name = "Jones"

For more information on expression attribute names, go to Accessing Item Attributes in the Amazon DynamoDB Developer Guide.

Type: String to String map

Required: No

ExpressionAttributeValues

One or more values that can be substituted in an expression.

Use the : (colon) character in an expression to dereference an attribute value. For example, suppose that you wanted to check whether the value of the ProductStatus attribute was one of the following:

Available | Backordered | Discontinued

You would first need to specify ExpressionAttributeValues as follows:

{ ":avail":{"S":"Available"}, ":back":{"S":"Backordered"}, ":disc":{"S":"Discontinued"} }

You could then use these values in a ConditionExpression, such as this:

ProductStatus IN (:avail, :back, :disc)

For more information on expression attribute values, go to Specifying Conditions in the Amazon DynamoDB Developer Guide.

Type: String to AttributeValue object map

Required: No

ReturnConsumedCapacity

A value that if set to TOTAL, the response includes ConsumedCapacity data for tables and indexes. If set to INDEXES, the response includes ConsumedCapacity for indexes. If set to NONE (the default), ConsumedCapacity is not included in the response.

Type: String

Valid Values: INDEXES | TOTAL | NONE

Required: No

ReturnItemCollectionMetrics

A value that if set to SIZE, the response includes statistics about item collections, if any, that were modified during the operation are returned in the response. If set to NONE (the default), no statistics are returned.

Type: String

Valid Values: SIZE | NONE

Required: No

ReturnValues

Use ReturnValues if you want to get the item attributes as they appeared before they were updated with the PutItem request. For PutItem, the valid values are:

  • NONE - If ReturnValues is not specified, or if its value is NONE, then nothing is returned. (This setting is the default for ReturnValues.)

  • ALL_OLD - If PutItem overwrote an attribute name-value pair, then the content of the old item is returned.

Type: String

Valid Values: NONE | ALL_OLD | UPDATED_OLD | ALL_NEW | UPDATED_NEW

Required: No

Response Syntax

{
    "Attributes": 
        {
            "string" :
                {
                    "B": "blob",
                    "BOOL": "boolean",
                    "BS": [
                        "blob"
                    ],
                    "L": [
                        AttributeValue
                    ],
                    "M": 
                        {
                            "string" :
                                AttributeValue
                        },
                    "N": "string",
                    "NS": [
                        "string"
                    ],
                    "NULL": "boolean",
                    "S": "string",
                    "SS": [
                        "string"
                    ]
                }
        },
    "ConsumedCapacity": {
        "CapacityUnits": "number",
        "GlobalSecondaryIndexes": 
            {
                "string" :
                    {
                        "CapacityUnits": "number"
                    }
            },
        "LocalSecondaryIndexes": 
            {
                "string" :
                    {
                        "CapacityUnits": "number"
                    }
            },
        "Table": {
            "CapacityUnits": "number"
        },
        "TableName": "string"
    },
    "ItemCollectionMetrics": {
        "ItemCollectionKey": 
            {
                "string" :
                    {
                        "B": "blob",
                        "BOOL": "boolean",
                        "BS": [
                            "blob"
                        ],
                        "L": [
                            AttributeValue
                        ],
                        "M": 
                            {
                                "string" :
                                    AttributeValue
                            },
                        "N": "string",
                        "NS": [
                            "string"
                        ],
                        "NULL": "boolean",
                        "S": "string",
                        "SS": [
                            "string"
                        ]
                    }
            },
        "SizeEstimateRangeGB": [
            "number"
        ]
    }
}
			

Response Elements

The following data is returned in JSON format by the service.

Attributes

The attribute values as they appeared before the PutItem operation, but only if ReturnValues is specified as ALL_OLD in the request. Each element consists of an attribute name and an attribute value.

Type: String to AttributeValue object map

ConsumedCapacity

The capacity units consumed by an operation. The data returned includes the total provisioned throughput consumed, along with statistics for the table and any indexes involved in the operation. ConsumedCapacity is only returned if the request asked for it. For more information, see Provisioned Throughput in the Amazon DynamoDB Developer Guide.

Type: ConsumedCapacity object

ItemCollectionMetrics

Information about item collections, if any, that were affected by the operation. ItemCollectionMetrics is only returned if the request asked for it. If the table does not have any local secondary indexes, this information is not returned in the response.

Each ItemCollectionMetrics element consists of:

  • ItemCollectionKey - The hash key value of the item collection. This is the same as the hash key of the item.

  • SizeEstimateRange - An estimate of item collection size, in gigabytes. This value is a two-element array containing a lower bound and an upper bound for the estimate. The estimate includes the size of all the items in the table, plus the size of all attributes projected into all of the local secondary indexes on that table. Use this estimate to measure whether a local secondary index is approaching its size limit.

    The estimate is subject to change over time; therefore, do not rely on the precision or accuracy of the estimate.

Type: ItemCollectionMetrics object

Errors

For information about the errors that are common to all actions, see Common Errors.

ConditionalCheckFailedException

A condition specified in the operation could not be evaluated.

HTTP Status Code: 400

InternalServerError

An error occurred on the server side.

HTTP Status Code: 500

ItemCollectionSizeLimitExceededException

An item collection is too large. This exception is only returned for tables that have one or more local secondary indexes.

HTTP Status Code: 400

ProvisionedThroughputExceededException

The request rate is too high, or the request is too large, for the available throughput to accommodate. The AWS SDKs automatically retry requests that receive this exception; therefore, your request will eventually succeed, unless the request is too large or your retry queue is too large to finish. Reduce the frequency of requests by using the strategies listed in Error Retries and Exponential Backoff in the Amazon DynamoDB Developer Guide.

HTTP Status Code: 400

ResourceNotFoundException

The operation tried to access a nonexistent table or index. The resource might not be specified correctly, or its status might not be ACTIVE.

HTTP Status Code: 400

Examples

Put an Item

The following example puts a new item into the Thread table, but only if there is not already an item in the table with the same key.

Sample Request

POST / HTTP/1.1
Host: dynamodb.<region>.<domain>;
X-Amz-Date: <Date>
Authorization: AWS4-HMAC-SHA256 Credential=<Credential>, SignedHeaders=content-length;content-type;host;user-agent;x-amz-content-sha256;x-amz-date;x-amz-target, Signature=<Signature>
User-Agent: <UserAgentString>
x-amz-content-sha256: <PayloadHash>
Content-Type: application/x-amz-json-1.0
Content-Length: <PayloadSizeBytes>     
Connection: Keep-Alive X-Amz-Target: DynamoDB_20120810.PutItem 

{
    "TableName": "Thread",
    "Item": {
        "LastPostDateTime": {
            "S": "201303190422"
        },
        "Tags": {
            "SS": ["Update","Multiple Items","HelpMe"]
        },
        "ForumName": {
            "S": "Amazon DynamoDB"
        },
        "Message": {
            "S": "I want to update multiple items in a single API call. What's the best way to do that?"
        },
        "Subject": {
            "S": "How do I update multiple items?"
        },
        "LastPostedBy": {
            "S": "fred@example.com"
        }
    },
    "ConditionExpression": "ForumName <> :f and Subject <> :s",
    "ExpressionAttributeValues": {
        ":f": {"S": "Amazon DynamoDB"},
        ":s": {"S": "How do I update multiple items?"}
    }
}
        

Sample Response

HTTP/1.1 200 OK
x-amzn-RequestId: <RequestId> 
x-amz-crc32: <Checksum>
Content-Type: application/x-amz-json-1.0
Content-Length: <PayloadSizeBytes>
Date: <Date>
 {
}