graph_ql

Examples of Graphql via Udemy Course

GraphQl Playground when serving application: http://localhost:4000/

General learnings about GraphQl:

Inside Resolvers, Query, [Method Name], the following args can be used:

[Method Name](parent, args, cxt, info){}

Parent is handy when working with relational data
Great information about the operations
Args object of args provided
Info Information about the operations acros the server
CTX contextual information

Accepted Scaler Types in Type Definition: String Boolean Int Float ID (unique identifiers)

Notes:


Type Definitions are similar to an Interface in OOP (Java, .Net, AS3 etc).
Acting as a contract between an entity and the information
it contacts, and what is required to be provided upon a graphql Query.

This example holds a very basic pattern with Query, however
typeDefs can contain many items, e.g. User, ShoppingCartItems, Posts, Ratings

const typeDefs = `
    type Query {
        id: ID! // Explanation mark means this field is required
        name: String!
        age: Int!
        employed: Boolean!
        gpa: float // gpa is not required in this example
    }
`

Resolvers contain Queries that can be made to retrieve data.
Again this is the simplest version, that returns hard coded values.
Next we'll show some examples that uncover the functionality and value of using
GraphQl.

const resolvers = {
    Query: {
        id() {
            return 323321
        },
        name() {
            return 'Nick'
        },
        age() {
            return 35
        },
        employed() {
            return true
        },
        gpa() {
            return null
        }
    }
}

Here is an example which is closer to the true implementation that would
be used in an app.

const typeDefs = `
    type Query {
        greeting(name: String): String!
        me: User
    }
    type User {
        id: ID!
        name: String!
        email: String!
        age: Int
    }
`

const resolvers = {
    Query: {
        greeting(parent, args, cxt, info) {
            if (!args.name) return 'name argument missing';
            return args.name;
        },
        me() {
            return {
                id: "1",
                name: "Bob",
                email: "bob@b.com",
                age: 20
            }
        }
    }
}

Querying GraphQl:

Go to: http://localhost:4000/

From the playground paste in this query and it will return the static
data stored inside the me() resolver.

query {
  me {
    id
    name
    email
    age
  }
}

Using Paramters with GraphQl:

query {
  greeting(name: "Jessy")
}

This parameter will be recieved by GraphQl inside the greeting resolver within the
'args' object.

Where the query will return "Jessy" if using the code in the example above.

````

Arrays

In this example, the grades are required, and the items as not nullable due to the use of the explanation mark. grades: [Int!]!

Resources

Database: https://www.prisma.io/

nicktaras/graph_ql

graph_ql

Resources