Custom response in token endpoint in IdentityServer4 - asp.net-core

Question

API details:.Net Core 3.1 REST API using IdentityServer4 version 3.1.3
I have many APIs which send responses in a specified format.
For e.g. Register endpoint returns below response:
{
"responseCode": 0,
"developerMessage": "Response code not specified.",
"clientMessage": null,
"data": {"id":123},
"exception": null
}
I developed the authentication server using IdentityServer4.
But, my token endpoint returns below response:
{
"access_token": "eyJhbGciOiJSUzI1NiIsImtpZCI6Ik...",
"expires_in": 1209600,
"token_type": "Bearer",
"refresh_token": "1u8_VOFHTaeqWEWd6R...",
"scope": "offline_access api1"
}
Now the requirement is that all the endpoints of the API should return the response in the same format.
Which means I need to change the response of the token (or more) endpoints.
I looked into the ICustomTokenResponseGenerator service (mentioned here) but all it does is adding more fields to the response. And it is from IdentityServer3
class CustomTokenResponseGenerator : ICustomTokenResponseGenerator
{
public Task<TokenResponse> GenerateAsync(ValidatedTokenRequest request, TokenResponse response)
{
response.Custom.Add("custom_field", "custom data");
return Task.FromResult(response);
}
}
But, I want to completely change the response.
Is there any other service that I can use to get the below response?
{
"responseCode": 0,
"developerMessage": "Response code not specified.",
"clientMessage": null,
"data":
{
"access_token": "eyJhbGciOiJSUzI1NiIsImtpZCI6Ik...",
"expires_in": 1209600,
"token_type": "Bearer",
"refresh_token": "1u8_VOFHTaeqWEWd6R...",
"scope": "offline_access api1"
},
"exception": null
}

Answer 1

As explained in your GitHub ticket:
IdentityServer is an OAuth implementation - what you are suggesting would be incompatible with OAuth and thus is not supported by us.
If you need to change the complete payload to something custom - write some middleware to intercept the response.