Layer7 API Management

I have a requirement to customize OTK error message.

OTK Version : 4.1

Gateway version : 9.2

e.g.

1. OTK error message default error message format is :

{
"error":"invalid_request",
"error_description":"Custom error description"
}

   2. Expecting OTK error message error message format is :

{
"error": {
"status": "400",
"errors": [
{
"fields": "["invalid_request"]",
"key": "error. missingDuplicate.parameters"
}
]
},
"data": {}
}

Please have a look at below approach and let me know how to achieve it.

Approach 1 : Override message creation in "OTK Fail with error message"

Approach 2 : Capture error message in "Global Message completed" and modify format

Approach 3 : Able to modify error message for each status code in customizations/#OTK Fail with error message

Challenges :

1. challenges in Approach 1 : how to disable "OTK Cache Store" and override error.msg context variable.
2. challenges in Approach 2 : Unable to get error message as part of ${response.mainpart} or ${resp.mainpart} and unable to expose as  "Export Variables from Fragment" in customizations/#OTK Fail with error message.
3. challenges in Approach 3 : Have to override all error code policy assertions, which is not a good practice.

I failed to achieve even though, was trying to modify "#OTK Cache Look Up Customization / "#OTK Cache Store Customization" . Please share your inputs.

I would not recommend Approach 1  and modifying OTK Fail with error message directly. To  disable caching of error messages completely you can copy the "isCached" context variable to the top of "#OTK Fail with error message" and set its value to true which will cause cache logic you show at line 255 to not cache error messages.

Approach 3 is the recommended approach and will persist upgrades. 

Thank you Stern for your valuable inputs,

I am able to disable cache but unable to modify/customize error.msg. Is there any way to get ${error.msg} inside "#OTK Fail with error message" or "Global Message completed"?

${error.msg} is set further down in the "OTK Fail with error message" assertion. TO override all OOB error messages you would need to copy all the error handling branches to "#OTK Fail with error message" and modify them accordingly. 

I would avoid using "Global Message completed" for this.