NestJS + GraphQL Federation and schema first GraphQLDefinitionsFactory - graphql

Question

I'am trying to use the GraphQL federation with the schema first approach. Before I switch to federation, I was using ts-node and a little script to generate my typings like this :
import { GraphQLDefinitionsFactory } from '#nestjs/graphql';
import { join } from 'path';
const definitionsFactory = new GraphQLDefinitionsFactory();
definitionsFactory.generate({
typePaths: ['./src/**/*.graphql'],
path: join(process.cwd(), 'src/graphql.schema.ts'),
outputAs: 'class',
});
This was working well until I switch to the federation approach and modifying my schema adding the #Key() directive in my sites.graphql file (schema first!) :
type Site #key(fields: "siteId") {
siteId: ID!
contractId: Int
dateStart: String
siteName: String
}
type Query {
GetSite(id: ID!): Site
}
Now, when I generate my classes, I have the following error :
> ts-node src/tools/generate-typings.ts
(node:84388) UnhandledPromiseRejectionWarning: Error: Unknown directive "#key".
The #key directive does not seem to be recognized. Do I miss something?
Thank you for your help

Answer 1

Ok, digging in the source code of graphql-definitions.factory.ts I found an undocumented option federation.
Changing my script to :
import { GraphQLDefinitionsFactory } from '#nestjs/graphql';
import { join } from 'path';
const definitionsFactory = new GraphQLDefinitionsFactory();
definitionsFactory.generate({
typePaths: ['./src/**/*.graphql'],
path: join(process.cwd(), 'src/graphql.schema.ts'),
outputAs: 'class',
federation: true
});
And it works now.
Ps: to run the project, don't forget to eventually disable the installSubscriptionHandlers in the GraphQLModule options.

Answer 2

For federated subgraphs you should used GraphQLFederationDefinitionsFactory instead:
import { join } from 'path';
import { GraphQLFederationDefinitionsFactory } from '#nestjs/graphql';
const definitionsFactory = new GraphQLFederationDefinitionsFactory();
definitionsFactory.generate({
typePaths: ['./src/**/*.graphql'],
path: join(process.cwd(), 'src/graphql.ts'),
defaultScalarType: 'unknown',
customScalarTypeMapping: {
DateTime: 'Date',
},
watch: true,
});

Answer 3

I have created the script to generate the federation schema
import { writeFileSync, readFileSync } from 'fs';
import { buildSubgraphSchema } from '#apollo/subgraph';
import { printSchema, DocumentNode } from 'graphql';
import gql from 'graphql-tag';
async function generateSchema() {
// auto generate schema file
const subGraphschema = readFileSync('./src/schema/schema.graphql', {
encoding: 'utf8',
flag: 'r',
});
const schema: DocumentNode = gql(subGraphschema);
const generatedSchema = buildSubgraphSchema({
typeDefs: schema,
});
writeFileSync(
'./public/schema.graphql',
printSchema(generatedSchema),
'utf8',
);
console.log(`Generated GraphQL schema:\n\n${printSchema(generatedSchema)}`);
}
generateSchema();