alexbarksdale/graphql

Exploring the realm of GraphQL

Reading GraphQL Types

• When a type ends with ! it means it will always return that type.
• If it doesn't contain ! it can return something like null
• users: [User!]!
  • users will always return an array([]!) always containing a user(User!) == [User!]!

GraphQL Types (Scalar Types)

• String
• Boolean
• Int
• Float
• ID

Type Definitions

• Nothing more than a regular schema

Resolvers

• These are functions that run when a query for something

Resolver Arguments

They are as follows in the exact order

• There are 4 arguments that get passed to all resolver functions
• object: useful when working with relational data. e.g a user having many posts
• args: Contains the operation arguments supplied (like a regular func)
• context (ctx): Useful when you want to share information across your GraphQL
• info: ...

Input Type

• You can only have scalar values within a input type

input CreateUserInput {
    name: String!
    email: String!
    age: Int
}

Context

• Useful when you want to share information across your GraphQL resolvers

const server = new GraphQLServer({
    typeDefs: './src/schema.graphql',
    resolvers,
    context: {
        db,
    },
});

TypeORM

• By default TypeORM infers the type based on the Typescript type.

- This column is inferred as type String aka VARCHAR in the database
@Column()
title: string;

• @Entity - Creates a table or document depending on the database type
• @PrimaryGeneratedColumn - marks the table generated as the primary column and auto increments the value

TypeGraphQL

• @ObjectType() - Marks a class as a type known to GraphQL
• @Field() - Create a type known to GraphQL

Variables in GraphQL

mutation Login($email: String!, $password:String!){
  login(email: $email, password: $password)
}