Hi! I’m a Japanese software engineer with Go and Typescript.I develop applications every day when work and play. These days I use GraphQL a lot with them. And I use Apollo, GraphQL Code Generator and gqlgen for that. They are my favorite projects. They have in common that generate code.
So, I want to generate client for Go.
There are client for Go:
These libraries are very simple and easy to handle and used by gqlgen. But these don’t generate code. I want to generate code by response of introspection query from server. The GraphQL Code Generator have it. This user will have a comfortable development life.
So I give gopher and myself the same experience as a web client engineer.
I prepared for that.
This is Go library for building GraphQL client with gqlgen
gqlgenc
What is gqlgenc ?
This is Go library for building GraphQL client with gqlgen
Motivation
Now, if you build GraphQL api client for Go, have choice:
These libraries are very simple and easy to handle
However, as I work with gqlgen and graphql-code-generator every day, I find out the beauty of automatic generation
So I want to automatically generate types.
Installation
go get -u github.com/Yamashou/gqlgenc
How to use
Client Codes Only
gqlgenc base is gqlgen with plugins. So the setting is yaml in each format
gqlgenc can be configured using a .gqlgenc.yml file,
model
package: generated
filename: ./models_gen.go # https://github.com/99designs/gqlgen/tree/master/plugin/modelgen
client:
package: generated
filename: ./client.go # Where should any generated client go?
models:
Int:
model: github.com/99designs/gqlgen/graphql.Int64
Date:
model: github.com/99designs/gqlgen/graphql.Time
endpoint:
url: https://api.annict.com/graphql # Where do you want to send your request?
headers: #…
Installation
go get -u github.com/Yamashou/gqlgenc
How to use
This is a client generator based on the gqlgen plugin. If you use it, choice CLI or a plugin. I will explain how to use it using the Github API. If you don’t read this sentence, read here.
First, You create .gqlgenc.yaml in your project root.
model:
filename: ./gen/models_gen.go
client:
filename: ./gen/client.go
models:
Date:
model: github.com/99designs/gqlgen/graphql.Time
endpoint:
url: https://api.github.com/graphql
headers:
Authorization: "Bearer ${GITHUB_TOKEN}" # public access token
query:
- "./query/*.graphql"
If you don’t have a github token, you see here
Next, You create query.graphql in /query.
This query get your repositories.
fragment LanguageFragment on Language {
id
name
}
query GetUser($repositoryFirst: Int!, $languageFirst: Int!) {
viewer {
id
name
repositories(first: $repositoryFirst, orderBy: {field: CREATED_AT, direction: DESC}) {
nodes {
id
name
languages(first: $languageFirst) {
nodes {
...LanguageFragment
}
}
}
}
}
}
Finally, You exec a command in your project root.
Your client code is generated in /gen.
Then, run this code:
package main
import (
"context"
"fmt"
"github.com/Yamashou/gqlgenc/client"
"github.com/Yamashou/gqlgenc/example/github/gen"
"net/http"
"os"
)
func main() {
// This example only read public repository. You don't need to select scopes.
token := os.Getenv("GITHUB_TOKEN")
authHeader := func(req *http.Request) {
req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token))
}
ctx := context.Background()
githubClient := &gen.Client{
Client: client.NewClient(http.DefaultClient, "https://api.github.com/graphql", authHeader),
}
getUser, err := githubClient.GetUser(ctx, 10, 10)
if err != nil {
fmt.Fprintf(os.Stderr, "error: %s", err.Error())
os.Exit(1)
}
fmt.Println(*getUser.Viewer.Name, getUser.Viewer.Repositories.Nodes[0].Name)
for _, repository := range getUser.Viewer.Repositories.Nodes {
fmt.Println(repository.Name)
for _, language := range repository.Languages.Nodes {
fmt.Println(language.Name)
}
}
}
https://github.com/Yamashou/gqlgenc/blob/master/example/github/main.go
To understand the example, you read this code, readme and gqlgen document. If you understand Japanese, read here.
Afterword
This article is my first post with English. You may have a sentence that don’t understand, but I’m very happy to have this challenge. Thank you for reading this to the end.
