SubGraph Plugin

A plugin for creating sub-selections of your graph. This Allows you to use the same code/types for multiple variants of your API.

One common use case for this is to share implementations between your public and internal APIs, by only exposing a subset of your graph publicly.

Usage

Install

yarn add @giraphql/plugin-sub-graph

Setup

import '@giraphql/plugin-sub-graph';
const builder = new SchemaBuilder<{
SubGraphs: 'Public' | 'Other';
}>({
plugins: ['GiraphQLSubGraph'],
subGraphs: {
defaultsForTypes: [],
inheritFieldGraphsFromType: true,
},
});
//in another file:
const schema = builder.toSchema({});
const publicSchema = builder.toSubGraphSchema({}, 'Public');
const otherSchema = builder.toSubGraphSchema({}, 'Other');

Options on Types

  • subGraphs: An optional array of sub-graph the type should be included in.

Object and Interface types:

  • defaultSubGraphsForFields: Default sub-graph for fields of the type to be included in.

Options on Fields

  • subGraphs: An optional array of sub-graph the field to be included in. If not provided, will

    fallback to:

    • defaultSubGraphsForFields if set on type

    • subGraphs of the type if subGraphs.fieldsInheritFromTypes was set in the builder

    • an empty array

Options on Builder

  • subGraphs.defaultForTypes: Specifies what sub-graph a type is part of by default.

  • subGraphs.fieldsInheritFromTypes: defaults to false. When true, fields on a type will default

    to being part of the same sub-graph as their parent type. Only applies when type does not have

    defaultSubGraphsForFields set.

You can mock any field by adding a mock in the options passed to builder.buildSchema under mocks.{typeName}.{fieldName}.

Usage

builder.queryType({
subGraphs: ['Public', 'Other'], // Query type will be available in default, Public, and Other schemas
defaultSubGraphsForFields: []; // Fields on the Query object will now default to not being a part of any subgraph
fields: (t) => ({
someField: t.string({
subGraphs: ['Other'] // someField will be in the default schema and "Other" sub graph, but not present in the Public sub graph
resolve: () => {
throw new Error('Not implemented');
},
}),
}),
});

Missing types

When creating a subgraph, the plugin will only copy in types that are included in the sub-graph, either by explicitly setting it on the type, or because the sub-graph is included in the default list. Like types, output fields that are not included in a sub-graph will also be omitted. Arguments and fields on Input types can not be removed because that would break assumptions about arguments types in resolves.

If a type that is not included in the sub-graph is referenced by another part of the graph that is included in the graph, a runtime error will be thrown when the sub graph is constructed. This can happen in a number of cases including cases where a removed type is used in the interfaces of an object, a member of a union, or the type of an field argument.