Rewrite rules – Common Problems

Rules are independent

• Unfortunately Rewrite Rules are totally independent of each other
• For example, assume you are trying to generate a 404 error response (status code and body together). See screenshot
• If, for example, the status code actually comes back as 403, the Body value will still be changed
• This problem is common when working with the OPTIONS HTTP method

“$” symbol in Response body

• If you have an unescaped “$” in your Response body value, the response can sometimes fail to complete
• See full detail of the problem this Stack Overflow post

Escaping a character

• Simply put a “\” character in front of the “$” symbol

Dealing with OPTIONS

• Using Rewrite rules on endpoints with an OPTIONS HTTP method can be especially tricky
• As mentioned previously, Rewrite rules are independent of each other
• See more detail the problem on Stack Overflow post

The workaround for GET and POST

• If you need to modify the Response body of the related POST or GET request you can add a rule to only match on response with bodies i.e. a OPTIONS response doesn’t contain a body
• Add either \{[\S\s]*\} or \[[\S\s]*\] into the “Value” textfield of the “Match” section

Enable the “Error Log” feature

• You can view additional logging details if you enable “Debug in Error Log” on the Rewrite screen

Open Error Log screen

• To view the error logs go to Window -> Error Log

Simple example

• In the following example, I am using a Rewrite to redirect the NY Times fav icon url to now fetch the Qantas fav icon instead
• You can see there are 2 records in the Error Log screen for each Rewrite rule