client

GraphQL Client in Go

An example of implementing a simple GraphQL client in Go to query against a public GraphQL service https://countries.trevorblades.com/. The client makes 2 calls:

• GraphQL request without any filter.
• GraphQL request with a filter passed as a parameter.

We can construct a GraphQL query as a string and pass it as plain text when making the API call. But for the construction of more complex queries, including support for passed arguments, we may want to use a GraphQL package, like the machinebox/graphql package.

Setup

1. Run the program

   $ make

Querying from the Playground

GraphQL is a querying language that can be embedded in a programming language like Go and a transport stack like HTTP. The following steps show how the same GraphQL queries can be made from the service GraphQL playground.

1. Go to https://countries.trevorblades.com/

2. Run the following query to return all countries.

   query {
     countries {
       code,
       name,
       languages {
         name
       }
     }
   }
   

3. Return all countries that matches country.code == "US" (case sensitive).

   query {
     countries(filter: {
       code: { eq: "US" }
     }) {
       code,
       name,
       languages {
         name
       }
     }
   }
   

Reference

• Machinebox GraphQL Package
• Introduction to GraphQL
• Passing Arguments in GraphQL