/
makeRemoteExecutableSchema.ts
131 lines (112 loc) · 3.77 KB
/
makeRemoteExecutableSchema.ts
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import { ApolloLink } from 'apollo-link';
import {
GraphQLFieldResolver,
GraphQLSchema,
Kind,
GraphQLResolveInfo,
BuildSchemaOptions,
DocumentNode,
} from 'graphql';
import { addResolversToSchema } from '../generate/index';
import { Fetcher, Operation } from '../Interfaces';
import { cloneSchema } from '../utils/index';
import { buildSchema } from '../polyfills/index';
import { addTypenameToAbstract } from '../delegate/addTypenameToAbstract';
import { checkResultAndHandleErrors } from '../delegate/checkResultAndHandleErrors';
import linkToFetcher, { execute } from '../stitch/linkToFetcher';
import { observableToAsyncIterable } from '../stitch/observableToAsyncIterable';
import mapAsyncIterator from '../stitch/mapAsyncIterator';
import { stripResolvers, generateProxyingResolvers } from './resolvers';
export type ResolverFn = (
rootValue?: any,
args?: any,
context?: any,
info?: GraphQLResolveInfo,
) => AsyncIterator<any>;
export default function makeRemoteExecutableSchema({
schema: schemaOrTypeDefs,
link,
fetcher,
createResolver = defaultCreateRemoteResolver,
createSubscriptionResolver = defaultCreateRemoteSubscriptionResolver,
buildSchemaOptions,
}: {
schema: GraphQLSchema | string;
link?: ApolloLink;
fetcher?: Fetcher;
createResolver?: (fetcher: Fetcher) => GraphQLFieldResolver<any, any>;
createSubscriptionResolver?: (
link: ApolloLink,
) => GraphQLFieldResolver<any, any>;
buildSchemaOptions?: BuildSchemaOptions;
}): GraphQLSchema {
let finalFetcher: Fetcher = fetcher;
if (finalFetcher == null && link != null) {
finalFetcher = linkToFetcher(link);
}
const targetSchema =
typeof schemaOrTypeDefs === 'string'
? buildSchema(schemaOrTypeDefs, buildSchemaOptions)
: schemaOrTypeDefs;
const createProxyingResolver = ({
operation,
}: {
operation: Operation;
}): GraphQLFieldResolver<any, any> => {
if (operation === 'query' || operation === 'mutation') {
return createResolver(finalFetcher);
}
return createSubscriptionResolver(link);
};
const resolvers = generateProxyingResolvers({
subschemaConfig: { schema: targetSchema, createProxyingResolver },
});
const remoteSchema = cloneSchema(targetSchema);
stripResolvers(remoteSchema);
addResolversToSchema({ schema: remoteSchema, resolvers });
return remoteSchema;
}
export function defaultCreateRemoteResolver(
fetcher: Fetcher,
): GraphQLFieldResolver<any, any> {
return async (_root, _args, context, info) => {
const fragments = Object.keys(info.fragments).map(
(fragment) => info.fragments[fragment],
);
let query: DocumentNode = {
kind: Kind.DOCUMENT,
definitions: [info.operation, ...fragments],
};
query = addTypenameToAbstract(info.schema, query);
const result = await fetcher({
query,
variables: info.variableValues,
context: { graphqlContext: context },
});
return checkResultAndHandleErrors(result, context, info);
};
}
export function defaultCreateRemoteSubscriptionResolver(
link: ApolloLink,
): GraphQLFieldResolver<any, any> {
return (_root, _args, context, info) => {
const fragments = Object.keys(info.fragments).map(
(fragment) => info.fragments[fragment],
);
let query: DocumentNode = {
kind: Kind.DOCUMENT,
definitions: [info.operation, ...fragments],
};
query = addTypenameToAbstract(info.schema, query);
const operation = {
query,
variables: info.variableValues,
context: { graphqlContext: context },
};
const observable = execute(link, operation);
const originalAsyncIterator = observableToAsyncIterable(observable);
return mapAsyncIterator(originalAsyncIterator, (result) => ({
[info.fieldName]: checkResultAndHandleErrors(result, context, info),
}));
};
}