DocsConditional logic
04 / 05

Conditional logic

How mock APIs use rules to determine responses.

How conditions work

Mock APIs can evaluate conditions to return different responses based on:

  • URL path parameters (e.g., /users/:id)
  • Query parameters (e.g., ?status=active)
  • Request body content (for POST/PUT requests)
  • Request headers

Condition fields

Conditions can check these request properties:

FieldDescription
params.*URL path parameters
query.*Query string parameters
body.*Request body fields (JSON)
headers.*Request headers

Examples

json
// Return 404 if user ID doesn't exist
{
  "field": "params.id",
  "operator": "not_in",
  "value": ["USR-001", "USR-002", "USR-003"],
  "response": { "status": 404, "body": { "error": "User not found" } }
}

// Return error if required field missing
{
  "field": "body.email",
  "operator": "not_exists",
  "response": { "status": 400, "body": { "error": "Email is required" } }
}