GraphQL Server Implementation Basics (Node.js) Quiz Quiz

Challenge your understanding of essential concepts, syntax, and workflow when implementing a GraphQL server in Node.js. This quiz covers schema definition, resolver functions, query handling, type specification, and error management to assess your proficiency in developing robust GraphQL APIs using Node.js.

1. Defining Schema Types in GraphQL

   Which syntax best describes how to define a User type with id and name fields in a GraphQL schema file?

   1. type User { id: ID! name: String! }
   2. User: type { id = int, name = str }
   3. define User { id: Integer, name: Text }
   4. User(id: ID!, name: String!)

   Explanation: The correct way to define a User type in a GraphQL schema is by using 'type' followed by the name and field definitions, such as 'type User { id: ID! name: String! }'. This syntax uses GraphQL's type language. The second option is incorrect because it uses assignment operators and incorrect type names. The third lacks the 'type' keyword and uses incorrect parentheses. The fourth uses non-GraphQL type names and an invalid 'define' keyword.

2. Role of Resolver Functions

   What is the primary role of resolver functions when creating a GraphQL server in Node.js?

   1. They resolve and return the requested data for each field in a query.
   2. They store the GraphQL queries in a database.
   3. They translate incoming HTTP requests to REST endpoints.
   4. They generate type definitions for the schema.

   Explanation: Resolver functions are responsible for fetching and returning the appropriate data for each field requested in a GraphQL query. They act as connectors between the schema and the data source. The first option describes schema generation, not data fetching. The second mixes up GraphQL with REST API functionality. The fourth option mistakenly claims that resolvers store queries, which is not their purpose.

3. Handling Query Parameters

   In GraphQL, how are query parameters, such as an ID for fetching a specific user, accessed inside a resolver function using Node.js?

   1. They are fetched from the request headers directly.
   2. They are accessed through the first parent argument.
   3. They appear in the args argument of the resolver.
   4. They are retrieved from the context argument.

   Explanation: When implementing resolver functions in Node.js, query parameters are made available in the args argument. This allows the function to access parameters like IDs or filters sent with the query. The context argument is typically used for authentication or shared data, not query parameters. The parent argument provides information about the parent object, not the arguments. Headers contain meta-information, not query parameters.

4. Scalar Types in GraphQL

   Which of the following is NOT a default scalar type in GraphQL that you can use when defining a Node.js schema?

   1. String
   2. Int
   3. Float
   4. JSON

   Explanation: The default scalar types in GraphQL include String, Int, Float, Boolean, and ID. JSON is not a built-in scalar type and typically requires custom scalar implementation. Float, Int, and String are all included by default and are available for use in schema definitions. Choosing JSON would be incorrect unless you explicitly define it as a custom scalar.

5. Error Handling Strategy

   When an error occurs inside a resolver function, how does GraphQL typically handle it in its response format?

   1. The server returns only an HTTP error status code and no data.
   2. The response includes neither data nor errors for failed queries.
   3. All fields return null, and no error information is sent back to the client.
   4. Both data and errors fields are present in the response, with errors describing what went wrong.

   Explanation: GraphQL generally responds with a JSON object containing both a data field and an errors field when something goes wrong. This way, partial data and detailed error information can be delivered together. The first option ignores the GraphQL response structure, as status codes remain the same. The third and fourth options do not follow the actual GraphQL response format, as errors are never silently omitted.