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smart_replace

Purpose​

smart_replace identifies values for smart replacement wherever they are encountered. For example, let's say we need to replace a set of unique user IDs spread throughout a large set of traffic. It would take a long time to meticulously define and replace each instance of the user ID. Instead, use smart_replace to match each user ID with a new value whenever it is encountered. Insert smart_replace at the beginning of a transform chain and the value being extracted will be matched with the new value at the end of the chain in the future.

Usage​

"type": "smart_replace",
"config": {
    "overwrite": "<boolean>",
}
  • overwrite - If false, the key=value mapping will be made permanently. If true, the key=value mapping will be rewritten each time smart_replace is called. This is helpful if you want to rotate values through a CSV continuously. For most use cases, overwrite=false (the default) is desired.

Example​

The smart_replace transform forms the heart of session or request ID replacement workflow.

Before and After Example​

Configuration​

{
   "type": "smart_replace",
   "config": {
       "overwrite": false
   }
}

Example Chains​

smart_replace() -> req_body() -> json_path(path="userId") -> rand_string(pattern="user_[0-9]{6}")

This will learn to replace the userId value with a random generated string throughout all future requests.

smart_replace(overwrite=true) -> res_body() -> json_path(path="sessionId") -> constant(value="test_session_123")

This will replace the sessionId with a constant value, overwriting the mapping each time.

smart_replace() -> http_req_header(header="X-Request-ID") -> regex(pattern="req_([0-9]+)", captureGroup=1) -> rand_string(pattern="[0-9]{8}")

This will extract the numeric part of request IDs and replace them with random 8-digit numbers consistently.

Before (Original Values - First Pass)​

  • User ID in Request: user_12345
  • Session ID in Response: sess_abc789xyz
  • Request ID Header: req_98765
  • User ID in Later Request: user_12345 (same user)

After (Smart Replace Transformed - First Pass)​

  • User ID in Request: user_847293 (generated replacement)
  • Session ID in Response: test_session_123 (constant replacement)
  • Request ID Header: 45821736 (random 8-digit replacement)
  • User ID in Later Request: user_847293 (same replacement used consistently)

Before (Original Values - Second Pass)​

  • New User ID: user_67890
  • Same Session ID: sess_abc789xyz (encountered again)
  • New Request ID: req_11223
  • Original User ID: user_12345 (encountered again)

After (Smart Replace Transformed - Second Pass)​

  • New User ID: user_156482 (new replacement generated)
  • Same Session ID: test_session_123 (same replacement used if overwrite=false, or new value if overwrite=true)
  • New Request ID: 87654321 (new replacement generated)
  • Original User ID: user_847293 (previously learned replacement reused)