Key matching - Amazon Simple Notification Service
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Key matching

You can use the exists operator to match incoming messages with or without specified properties in the filter policy. exists matching only works on leaf nodes. It does not work on intermediate nodes.

  • Use "exists": true to match incoming messages that include the specified property. The key must have a non-null and non-empty value.

    For example, the following policy property uses the exists operator with a value of true:

    "store": [{"exists": true}]

    It matches any list of message attributes that contains the store attribute key, such as the following:

    "store": {"Type": "String", "Value": "fans"}
"customer_interests": {"Type": "String.Array", "Value": "[\"baseball\", \"basketball\"]"}

    It also matches either of the following message body:

    {
    "store": "fans"
    "customer_interests": ["baseball", "basketball"]
}

    However, it doesn't match any list of message attributes without the store attribute key, such as the following:

    "customer_interests": {"Type": "String.Array", "Value": "[\"baseball\", \"basketball\"]"}

    Nor does it match the following message body:

    {
    "customer_interests": ["baseball", "basketball"]
}

  • Use "exists": false to match incoming messages that don't include the specified property.

    Note

    "exists": false only matches if at least one attribute is present. An empty set of attributes results in the filter not matching.

    For example, the following policy property uses the exists operator with a value of false:

    "store": [{"exists": false}]

    It doesn't match any list of message attributes that contains the store attribute key, such as the following:

    "store": {"Type": "String", "Value": "fans"}
"customer_interests": {"Type": "String.Array", "Value": "[\"baseball\", \"basketball\"]"}

    It also doesn’t match the following message body:

    {
    "store": "fans"
    "customer_interests": ["baseball", "basketball"]
}

    However, it matches any list of message attributes without the store attribute key, such as the following:

    "customer_interests": {"Type": "String.Array", "Value": "[\"baseball\", \"basketball\"]"}

    It also matches the following message body:

    {
    "customer_interests": ["baseball", "basketball"]
}