Type merging

[Rodeoclash]

Out of interest, are you planning on adding the type merging concept to the GraphQL mesh library?

In particular, what is described here: https://www.graphql-tools.com/docs/stitch-type-merging would be of great use to us when merging two remote GraphQL servers which are not federated but share a common User type.

[ardatan]

Yes we're planning to add type merging to Mesh's declarative API!

[Rodeoclash]

After a bit of investigation, we've produced the following patch which seems to enable type merging in master:

--- ./node_modules/@graphql-mesh/runtime/index.cjs.js   2021-05-28 05:41:43.338256290 +0000
+++ ./node_modules/@graphql-mesh/runtime/index.cjs.js   2021-05-28 05:41:37.066225272 +0000
@@ -217,6 +217,7 @@
            contextVariables: source.contextVariables || [],
            handler: apiSource.handler,
            batch: 'batch' in source ? source.batch : true,
+            merge: apiSource.merge,
        });
    }));
    let unifiedSchema = await options.merger({
--- ./node_modules/@graphql-mesh/config/index.cjs.js    2021-05-28 05:55:50.142242912 +0000
+++ ./node_modules/@graphql-mesh/config/index.cjs.js    2021-05-28 05:55:34.614170699 +0000
@@ -339,6 +339,7 @@
                     introspectionCache: handlerIntrospectionCache,
                 }),
                 transforms,
+                 merge: mergedTypeConfigMap,
             };
         })),
         Promise.all(((_b = config.transforms) === null || _b === void 0 ? void 0 : _b.map(async (t) => {

using a config like:

sources:
    - name: platform
      typeMerging:
          - typeName: UserData
            fieldName: userData
            selectionSet: '{ id }'
            args:
                id: '{root.id}'
      handler:
          graphql:
              endpoint: 'http://nginx/graphql-rpl'
              operationHeaders:
                  Authorization: '{context.headers.authorization}'

    - name: harvester
      typeMerging:
          - typeName: UserData
            fieldName: userData
            selectionSet: '{ id }'
            args:
                id: '{root.id}'
      handler:
          graphql:
              endpoint: 'http://harvester:8080/query'
              operationHeaders:
                  Authorization: '{context.headers.authorization}'

serve:
    port: 5000
    hostname: 0.0.0.0

Just so we understand, what's the reasoning behind the missing lines that prevent enabling it? We just want to make sure that by turning things on, we're not accidently breaking something else.

[nemonemi]

@Rodeoclash , what do you think is left here to be done?

[ardatan]

Type merging will be available in the next release for @graphql-mesh/config and runtime packages in a few minutes :)
01cf892

The only missing thing is the documentation for now. We will work on it soon. In the meanwhile, you can take a look at GraphQL Tools' one.

[ardatan]

New Type Merging is really close!
https://codesandbox.io/s/inspiring-platform-4j2ki?file=/.meshrc.yml
https://github.com/Urigo/graphql-mesh/blob/refactor/packages/transforms/type-merging/yaml-config.graphql

[Rodeoclash]

@ardatan confirmed it's working great for us (and is in our master branch 👀 )