Local Mocking API doesn't honour custom resolver response template names

[ghost]

Describe the bug When custom resolver response templates have been defined with a non-standard name, even though those names are defined in the resolver CloudFormation template, these names are not used. Instead the local mocking code looks for a response template with the same name as the request template, but with .res.vtl extension.

Note that the same setup works fine non-locally after an amplify push

To Reproduce Create a custom resolver for a mutation eg. Mutation.createBodyBlock.

1. Create a file in <api>/resolvers/Mutation.createBodyBlock.req.vtl.
2. Create a file in <api>/resolvers/passthrough.res.vtl
3. Create a CloudFormation template entry in stacks/CustomResources.json which specifies the above two locations for the Request and Response portions of the resolver:

   "MutationCreateBodyBlockResolver": {
     "Type": "AWS::AppSync::Resolver",
     "Properties": {
       "ApiId": {
         "Ref": "AppSyncApiId"
       },
       "DataSourceName": "BasicBlockTable",
       "TypeName": "Mutation",
       "FieldName": "createBodyBlock",
       "RequestMappingTemplateS3Location": {
         "Fn::Sub": [
           "s3://${S3DeploymentBucket}/${S3DeploymentRootKey}/resolvers/Mutation.createBodyBlock.req.vtl",
           {
             "S3DeploymentBucket": {
               "Ref": "S3DeploymentBucket"
             },
             "S3DeploymentRootKey": {
               "Ref": "S3DeploymentRootKey"
             }
           }
         ]
       },
       "ResponseMappingTemplateS3Location": {
         "Fn::Sub": [
           "s3://${S3DeploymentBucket}/${S3DeploymentRootKey}/resolvers/passthrough.res.vtl",
           {
             "S3DeploymentBucket": {
               "Ref": "S3DeploymentBucket"
             },
             "S3DeploymentRootKey": {
               "Ref": "S3DeploymentRootKey"
             }
           }
         ]
       }
     }
   }

4. Start local mocking: amplify mock api
5. See error:

   Failed to start API Mock endpoint Error: Invalid config for UNIT_RESOLVER {"dataSourceName":"BasicBlockTable","typeName":"Mutation","fieldName":"createBodyBlock","requestMappingTemplateLocation":"resolvers/Mutation.createBodyBlock.req.vtl","responseMappingTemplateLocation":"resolvers/Mutation.createBodyBlock.res.vtl","kind":"UNIT"} 
   Missing mapping template resolvers/Mutation.createBodyBlock.res.vtl

Expected behavior It should use the name provided in the stack for the response template, and not assume that it's the same as the request template with a different suffix.

[pspanchal]

actually it does not even take the name for request template. I think it is taking the template names from fieldname parameter.

[nikhname]

This is fixed by https://github.com/aws-amplify/amplify-cli/pull/2355

[alireza8101]

The problem still exists. Failed to start API Mock endpoint Error: Invalid config for UNIT_RESOLVER {"dataSourceName":"TodoTable","typeName":"Query","fieldName":"scanTodos","requestMappingTemplateLocation":"resolvers/Query.scanTodos.req.vtl","responseMappingTemplateLocation":"resolvers/Query.scanTodos.res.vtl","kind":"UNIT"} Missing mapping template resolvers/Query.scanTodos.req.vtl

[dryhurst]

running npm install -g @aws-amplify/cli to upgrade to the newest version fixed this for me. i am on windows and this patch fixed my issue: https://github.com/aws-amplify/amplify-cli/commit/87c4ad59a701995220946ad35f1491f0d4b57325

thank you team

[github-actions[bot]]

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