gqlgen 
What is gqlgen?
gqlgen is a Go library for building GraphQL servers without any fuss.
- gqlgen is based on a Schema first approach — You get to Define your API using the GraphQL Schema Definition Language.
- gqlgen prioritizes Type safety — You should never see
map[string]interface{}here. - gqlgen enables Codegen — We generate the boring bits, so you can focus on building your app quickly.
Still not convinced enough to use gqlgen? Compare gqlgen with other Go graphql implementations
Getting Started
- To install gqlgen run the command
go get github.com/99designs/gqlgenin your project directory. - You could initialize a new project using the recommended folder structure by running this command
go run github.com/99designs/gqlgen init.
You could find a more comprehensive guide to help you get started here.
We also have a couple of real-world examples that show how to GraphQL applications with gqlgen seamlessly, You can see these examples here or visit godoc.
Reporting Issues
If you think you've found a bug, or something isn't behaving the way you think it should, please raise an issue on GitHub.
Contributing
We welcome contributions, Read our Contribution Guidelines to learn more about contributing to gqlgen
Frequently asked questions
How do I prevent fetching child objects that might not be used?
When you have nested or recursive schema like this:
type User {
id: ID!
name: String!
friends: [User!]!
}
You need to tell gqlgen that it should only fetch friends if the user requested it. There are two ways to do this;
-
Using Custom Models
Write a custom model that omits the friends field:
type User struct {
ID int
Name string
}
And reference the model in gqlgen.yml:
# gqlgen.yml
models:
User:
model: github.com/you/pkg/model.User # go import path to the User struct above
-
Using Explicit Resolvers
If you want to Keep using the generated model, mark the field as requiring a resolver explicitly in gqlgen.yml like this:
# gqlgen.yml
models:
User:
fields:
friends:
resolver: true # force a resolver to be generated
After doing either of the above and running generate we will need to provide a resolver for friends:
func (r *userResolver) Friends(ctx context.Context, obj *User) ([]*User, error) {
// select * from user where friendid = obj.ID
return friends, nil
}
You can also use inline config with directives to achieve the same result
directive @goModel(model: String, models: [String!]) on OBJECT
| INPUT_OBJECT
| SCALAR
| ENUM
| INTERFACE
| UNION
directive @goField(forceResolver: Boolean, name: String) on INPUT_FIELD_DEFINITION
| FIELD_DEFINITION
type User @goModel(model: "github.com/you/pkg/model.User") {
id: ID! @goField(name: "todoId")
friends: [User!]! @goField(forceResolver: true)
}
Can I change the type of the ID from type String to Type Int?
Yes! You can by remapping it in config as seen below:
models:
ID: # The GraphQL type ID is backed by
model:
- github.com/99designs/gqlgen/graphql.IntID # An go integer
- github.com/99designs/gqlgen/graphql.ID # or a go string
This means gqlgen will be able to automatically bind to strings or ints for models you have written yourself, but the first model in this list is used as the default type and it will always be used when:
- Generating models based on schema
- As arguments in resolvers
There isn't any way around this, gqlgen has no way to know what you want in a given context.
