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The Modify Phase

Scope of the phase

This phase is used in a modifying extension and is optional for its operation (the modify section may be either absent or present in the YAML file).

This phase should be absent from the non-modifying extension's YAML file.

Read about the extension types in detail here.

Request elements description syntax

When creating a FAST extension, you need to understand the structure of the HTTP request sent to the application and that of the HTTP response received from the application in order to correctly describe the request elements that you need to work with using the points.

To see detailed information, proceed to this link.

This phase modifies values of a baseline request's parameters, if it is necessary. Note that you cannot add a new element that is absent from the baseline request using the Modify phase. For example, you cannot add the Cookie HTTP header if the baseline request does not contain it.

The modify section in the extension YAML file contains an array of <key: value> pairs. Each pair describes a certain request element (the key) and data that should be inserted into this element (the value). The key can contain regular expressions in the Ruby regular expressions format. You cannot apply regular expressions to the key's value.

In the Modify phase, you can assign new values to the element or delete the element's data.

  • If the key's value is set, then this value will be assigned to the corresponding baseline request element. If there is no element corresponding to the key in the baseline request, then no new element insertion will be performed.

    Example 1

    'HEADER_COOKIE_value': 'C=qwerty123'

    Modify phase

  • If the key's value is not set, then the corresponding baseline request element's value will be cleared.


    'HEADER_COOKIE_value': ""


In the example below, the baseline request will be modified in the following way:

  1. The Content-Type header's value will be replaced with application/xml.
  2. The uid GET parameter's value will be cleared (the parameter itself will not be removed).
- "HEADER_CONTENT-TYPE_value": "application/xml"
- "GET_uid_value": ""