Use expressions to define inputs by extracting the relevant part of a whole input - Amazon Bedrock

Use expressions to define inputs by extracting the relevant part of a whole input

When you configure the inputs for a node, you must define it in relation to the whole input that will enter the node. The whole input can be a string, number, boolean, array, or object. To define an input in relation to the whole input, you use a subset of supported expressions based off JsonPath. Every expression must begin with $.data, which refers to the whole input. Note the following for using expressions:

  • If the whole input is a string, number, or boolean, the only expression that you can use to define an individual input is $.data

  • If the whole input is an array or object, you can use extract a part of it to define an individual input.

As an example to understand how to use expressions, let's say that the whole input is the following JSON object:

{
    "animals": {
        "mammals": ["cat", "dog"],
        "reptiles": ["snake", "turtle", "iguana"]
    },
    "organisms": {
        "mammals": ["rabbit", "horse", "mouse"],
        "flowers": ["lily", "daisy"]
    },
    "numbers": [1, 2, 3, 5, 8]
}

You can use the following expressions to extract a part of the input (the examples refer to what would be returned from the preceding JSON object):

Expression Meaning Example Example result
$.data The entire input. $.data The entire object
.name The value for a field called name in a JSON object. $.data.numbers [1, 2, 3, 5, 8]
[int] The member at the index specified by int in an array. $.data.animals.reptiles[2] turtle
[int1, int2, ...] The members at the indices specified by each int in an array. $.data.numbers[0, 3] [1, 5]
[int1:int2] An array consisting of the items at the indices between int1 (inclusive) and int2 (exclusive) in an array. Omitting int1 or int2 is equivalent to the marking the beginning or end of the array. $.data.organisms.mammals[1:] ["horse", "mouse"]
* A wildcard that can be used in place of a name or int. If there are multiple results, the results are returned in an array. $.data.*.mammals [["cat", "dog"], ["rabbit", "horse", "mouse"]]