JSON: Extracting a variable

Key Concepts

With an API that returns a JSON body, you can use conditions set in the Conditions tab to extract results and give them a variable name. You can also set a pass/fail condition that depends on a specific string or result being returned.

Handling Content

Most REST APIs return data in dictionary objects, also known as mappings. They are indicated by { "curly braces". To find a value, use the key name to index into the object.

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Example

Use a dot (.) to access attributes of a JSON object. Alternatively, subscript syntax ([]) can be used. The following expressions are equivalent:

foo.bar
foo['bar']

Handling a List

Lists, or Arrays are a sequential order of values or objects. In JSON they are indicated by a [ "square bracket". To find a value, you use the zero-based index of the item in the list.

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Picking the first item in a list

If the response is a list, you can access the first item with either of these expressions:

my_list[0]
my_list.0

Example: Pick Verify a Specific Word from a JSON body

Let us assume we want to verify that the sixth word returned in a result is 'What' and set a pass condition contingent on it being the word having that value.

The returned JSON looks like this:

{
    "Recognition": {
        "Info": { "metrics": { "audioTime": 7.94000006, "audioBytes": 127092 } }, 
        "Status": "OK", 
        "ResponseId": "f160c005a1b78d2abda5eda4aa935a6f", 
        "NBest": [
            {
                "Confidence": 0.39000000000000001, 
                "ResultText": "Hello this is a test. What time is it goodbye.", 
                "LanguageId": "en-US", 
                "Grade": "accept", 
                "Hypothesis": "hello this is a test what time is it goodbye", 
                "Words": [
                    "Hello", 
                    "this", 
                    "is", 
                    "a", 
                    "test.", 
                    "What", 
                    "time", 
                    "is", 
                    "it", 
                    "goodbye."
                ]
            }
        ]
    }
}

To extract the sixth word, we can use either of these constructions:

Recognition.NBest.0.Words.5

or

Recognition.NBest[0].Words[5]

In the Assertions section for the API Call Edit tab, we would enter the following to create the conditional condition: