extend schema during runtime

[roderm]

What happened?

With GraphQL SDL it's possible to extend a schema, this works well if the extensions are given at compile time. If e.g. as plugin is loaded during runtime, the Schema can be extended, but resolvers can't be added:

schema := generated.NewExecutableSchema(generated.Config{Resolvers: &graph.Resolver{}})
schemaType := schema.Schema().Types["Todo"]
schemaType.Fields = append(schemaType.Fields, &ast.FieldDefinition{
	Name: "github_issue",
	Type: ast.NamedType("String", nil),
})
schemaType := schema.Schema().Types["NewTodo"]
schemaType.Fields = append(schemaType.Fields, &ast.FieldDefinition{
	Name: "github_issue",
	Type: ast.NamedType("String", nil),
})

• introspection shows the fields
• for Inputs the fields are just ignored
• querying the field throws "unknown field github_issue" from resolving

What did you expect?

Mutation

Getting the added field over the passed in Context. This would also only work for Types defined in the original schema oder builtin types. Else a map[string]interface{} must be used.

func (r *mutationResolver) CreateTodo(ctx context.Context, input model.NewTodo) (*model.Todo, error) {
	rawInput := graphql.CollectInputs(ctx)
	...
}

Query

Adding custom resolver to the Schema (executableSchema/executionContext) to fill manually:

schema := generated.NewExecutableSchema(generated.Config{Resolvers: &resolver})
schemaType, ok := schema.Schema().Types["Todo"]
schemaType.Fields = append(schemaType.Fields, 
	&ast.FieldDefinition{
		Name: "github_url",
		Type: ast.NamedType("String", nil),
	},
)
schema.AddResolver("Todo.github_url", func(ctx context.Context, field graphql.CollectedField, obj *model.Todo) graphql.Marshaler {
	return graphql.MarshalString("https://github.com/....")
})

Merge Schema

To keep comfort of the generation but still being able to extend during runtime, a merge during runtime would be nice:

schema1 := generated.NewExecutableSchema(generated.Config{Resolvers: &resolver})
schema2 := generatedExt.NewExecutableSchema(generatedExt.Config{Resolvers: &resolverExt})
schema.Extend(schema2)

versions

• gqlgen version? v0.16.0
• go version? 1.17

Would love to contribute this feature, but currently no idea where to begin. Is this use case reasonable and wanted by others as well?

[roderm]

I've created a protoype for this feature. With this it's possible to use schema1.Extend(schema2), but complexity and tests are not yet implemented.
Would love some feedback.

[ChildWangWorld]

Great job ~

[khanakia]

@roderm was this feature ever merged to main repo ?

[roderm]

@khanakia it has not been merged. Also I tried to solve this use-case partly with federation, I still had to implement some logic for inputs in this library.
You can find them here: https://github.com/roderm/gqlgen/commits/rot/schema/

• The basic idea on this is to add an extend input SDL to the schema and register and afterUnmarshal function to catch the other fields. This is used for filter, order and batch inputs as their is no apollo federation solution for this yet.
• Additionaly a graphQL service created with a fork of graphql-go, I extend the inputs with federation and pack both services behind a graphql-go-tools gateway

[khanakia]

Got it

[roderm]

If I find the time to create the tests for the "input-only" extension, I'll try to get a PR here.