QueryFilter (legacy) - Amazon DynamoDB (original) (raw)

Note

We recommend that you use the new expression parameters instead of these legacy parameters whenever possible. For more information, see Using expressions in DynamoDB. For specific information on the new parameter replacing this one, use FilterExpression instead..

In a Query operation, the legacy conditional parameter QueryFilter is a condition that evaluates the query results after the items are read and returns only the desired values.

This parameter does not support attributes of type List or Map.

Note

A QueryFilter is applied after the items have already been read; the process of filtering does not consume any additional read capacity units.

If you provide more than one condition in the QueryFilter map, then by default all of the conditions must evaluate to true. In other words, the conditions are combined using the AND operator. (You can use theConditionalOperator (legacy) 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.)

Note that QueryFilter does not allow key attributes. You cannot define a filter condition on a partition key or a sort key.

Each QueryFilter element consists of an attribute name to compare, along with the following:

• AttributeValueList - One or more values to evaluate against the supplied attribute. The number of values in the list depends on the operator specified in ComparisonOperator.
  For type Number, value comparisons are numeric.
  String value comparisons for greater than, equals, or less than are based on UTF-8 binary encoding. For example, a is greater thanA, and a is greater thanB.
  For type Binary, DynamoDB treats each byte of the binary data as unsigned when it compares binary values.
  For information on specifying data types in JSON, see DynamoDB low-level API.
• ComparisonOperator - A comparator for evaluating attributes. For example: equals, greater than, and less than.
  The following comparison operators are available:
  EQ | NE | LE | LT | GE | GT | NOT_NULL | NULL | CONTAINS | NOT_CONTAINS | BEGINS_WITH | IN | BETWEEN

Use FilterExpression instead – Example

Suppose you wanted to query the Music table and apply a condition to the matching items. You could use aQuery request with a QueryFilter parameter, as in this AWS CLI example:

aws dynamodb query \
    --table-name Music \
    --key-conditions '{
        "Artist": {
            "ComparisonOperator": "EQ",
            "AttributeValueList": [ {"S": "No One You Know"} ]
        }   
    }' \
    --query-filter '{
        "Price": {
            "ComparisonOperator": "GT",
            "AttributeValueList": [ {"N": "1.00"} ]
        }   
    }'  

You can use a FilterExpression instead:

aws dynamodb query \
    --table-name Music \
    --key-condition-expression 'Artist = :a' \
    --filter-expression 'Price > :p' \
    --expression-attribute-values '{
        ":p": {"N":"1.00"}, 
        ":a": {"S":"No One You Know"}
    }'