Make AWS Amplify support custom fields (Mutation/Query)

0.README.md

1. Add new custom schema to schema.graphql file

2. Create custom request/response mapping resolvers file in resolvers folder. The file should look like this:

   • REQUEST_MAPPING: Mutation.putUser.req.vtl
   • RESPONSE_MAPPING: Mutation.putUser.res.vtl

3. Update CustomResources.json file in stack folder

1.schema.graphql

type User @model {
  id: ID!
  displayName: String!
}

type Mutation {
  # THIS IS OUR CUSTOM FIELD
  putUser(displayName: String!): User
}

2.1.Mutation.putUser.req.vtl

## [Start] Prepare DynamoDB PutItem Request. **
{
  "version": "2017-02-28",
  "operation": "PutItem",
  "key": {
    "id": $util.dynamodb.toDynamoDBJson($util.defaultIfNullOrBlank($ctx.args.id, $util.autoId())),
  },
  "attributeValues": {
    "displayName": $util.dynamodb.toDynamoDBJson($ctx.args.displayName)
  }
}
## [End] Prepare DynamoDB PutItem Request. **

2.2.Mutation.putUser.res.vtl

$util.toJson($context.result)

3.CustomResources.json

{
	"AWSTemplateFormatVersion": "2010-09-09",
	"Description": "An auto-generated nested stack.",
	"Metadata": {},
	"Parameters": {
		"AppSyncApiId": {
			"Type": "String",
			"Description": "The id of the AppSync API associated with this project."
		},
		"AppSyncApiName": {
			"Type": "String",
			"Description": "The name of the AppSync API",
			"Default": "AppSyncSimpleTransform"
		},
		"env": {
			"Type": "String",
			"Description": "The environment name. e.g. Dev, Test, or Production",
			"Default": "NONE"
		},
		"S3DeploymentBucket": {
			"Type": "String",
			"Description": "The S3 bucket containing all deployment assets for the project."
		},
		"S3DeploymentRootKey": {
			"Type": "String",
			"Description": "An S3 key relative to the S3DeploymentBucket that points to the root\nof the deployment directory."
		}
	},
	"Resources": {
		
		"_comment": "JUST PUT YOUR CUSTOM QUERIES OR MUTATIONS IN RESOURCES BLOCK............",
		
		"MutationPutUserResolver": {
		  "Type": "AWS::AppSync::Resolver",
		  "Properties": {
			"ApiId": {
			  "Ref": "AppSyncApiId"
			},
			"DataSourceName": "UserTable",
			"TypeName": "Mutation",
			"FieldName": "putUser",
			"RequestMappingTemplateS3Location": {
			  "Fn::Sub": [
				"s3://${S3DeploymentBucket}/${S3DeploymentRootKey}/resolvers/Mutation.putUser.req.vtl",
				{
				  "S3DeploymentBucket": {
					"Ref": "S3DeploymentBucket"
				  },
				  "S3DeploymentRootKey": {
					"Ref": "S3DeploymentRootKey"
				  }
				}
			  ]
			},
			"ResponseMappingTemplateS3Location": {
			  "Fn::Sub": [
				"s3://${S3DeploymentBucket}/${S3DeploymentRootKey}/resolvers/Mutation.putUser.res.vtl",
				{
				  "S3DeploymentBucket": {
					"Ref": "S3DeploymentBucket"
				  },
				  "S3DeploymentRootKey": {
					"Ref": "S3DeploymentRootKey"
				  }
				}
			  ]
			}
		  }
		},

		"EmptyResource": {
			"Type": "Custom::EmptyResource",
			"Condition": "AlwaysFalse"
		}
	},
	"Conditions": {
		"HasEnvironmentParameter": {
			"Fn::Not": [
				{
					"Fn::Equals": [
						{
							"Ref": "env"
						},
						"NONE"
					]
				}
			]
		},
		"AlwaysFalse": {
			"Fn::Equals": [
				"true",
				"false"
			]
		}
	},
	"Outputs": {
		"EmptyOutput": {
			"Description": "An empty output. You may delete this if you have at least one resource above.",
			"Value": ""
		}
	}
}

@koingdev
Hi, how are you? Thank you for helping me out for all of this. I'm finally making some progress and got to the point that I have to query all public journals from all the users on the site. I believe I will have to use custom resolver for this and am not still clear how to set this up.

I just copied over the files you shared here on my project and wanted to see if you can just check really quick.

I assume I will have to edit Query.getPublicJournals.req.vtl to query all journals privacy = PUBLIC on the Journal table?