SubGraph

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 SubGraphPlugin from '@giraphql/plugin-sub-graph';
const builder = new SchemaBuilder<{
SubGraphs: 'Public' | 'Internal';
}>({
plugins: [SubGraphPlugin],
subGraphs: {
defaultsForTypes: [],
inheritFieldGraphsFromType: true,
},
});
//in another file:
const schema = builder.toSchema({});
const publicSchema = builder.toSchema({ subGraph: 'Public' });
const internalSchema = builder.toSchema({ subGraph: 'Internal' });
// You can also build a graph using multiple subgraphs:
const combinedSchema = builder.toSchema({ subGraph: ['Internal', 'Public'] });

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

Missing types

When creating a sub-graph, 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.