Type script is showing error not mentioning argument type for each arguments:
Mutation: {
createUser: (parent, args, context, info) =>{
}
I can solve by using any type, but what are the correct types?
Mutation: {
createUser: (parent: any, args: any, context: any, info: any) =>{
}
If you enable all strict type-checking options in tsconfig.json, you should add TS type for everything.
Let's take a look at the type of resolver.
export declare type IFieldResolver<TSource, TContext, TArgs = Record<string, any>> = (source: TSource, args: TArgs, context: TContext, info: GraphQLResolveInfo & {
mergeInfo: MergeInfo;
}) => any;
Resolver arguments:
parent - For resolvers of top-level fields with no parent (such as fields of Query, Mutation), this value is undefined. So the TS type is undefined
args - As you can see from the type, it must meet the type parameters in generic constraints Record<string, any>. Since the actual parameter is passed from the Graphql client, we need to define the Args type/interface for each resolver.
context - It's a generic parameter, we need to define the application context interface by ourselves.
info - The TS type already there GraphQLResolveInfo & { mergeInfo: MergeInfo }
An working example:
E.g.
import express from 'express';
import { ApolloServer, gql, MergeInfo } from 'apollo-server-express';
import { GraphQLResolveInfo } from 'graphql';
const app = express();
const typeDefs = gql`
type User {
email: String!
}
type Query {
user: User
}
type Mutation {
createUser(email: String!, password: String!): Boolean
}
`;
export declare type IFieldResolver<TSource, TContext, TArgs = Record<string, any>> = (source: TSource, args: TArgs, context: TContext, info: GraphQLResolveInfo & {
mergeInfo: MergeInfo;
}) => any;
type CreateUserArgs = {
email: string;
password: string;
};
interface AppContext {
userService: UserService;
}
const resolvers = {
Query: {},
Mutation: {
createUser: (
parent: undefined,
args: CreateUserArgs,
context: AppContext,
info: GraphQLResolveInfo & { mergeInfo: MergeInfo },
) => {
console.log(parent);
return context.userService.createUser(args.email, args.password);
},
},
};
interface UserService {
createUser(email: string, password: string): boolean;
}
class UserServiceImpl {
createUser(email: string, password: string) {
return true;
}
}
const server = new ApolloServer({
typeDefs,
resolvers,
context: {
userService: new UserServiceImpl(),
},
});
server.applyMiddleware({ app, path: '/graphql' });
app.listen(8080, () => console.log('Apollo server started at http://localhost:8080'));
package versions:
"typescript": "^3.9.6",
"apollo-server": "^2.15.1",
"graphql": "^14.6.0",
GraphQL Query in client-side:
mutation{
createUser(email: "teresa@gmail.com", password: "1234")
}
Response:
{
"data": {
"createUser": true
}
}
Logs in server-side:
Apollo server started at http://localhost:8080
undefined
