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
-
mkdir example cd example go mod init example -
Add
github.com/99designs/gqlgento your project's tools.goprintf '// +build tools\npackage tools\nimport (_ "github.com/99designs/gqlgen"\n _ "github.com/99designs/gqlgen/graphql/introspection")' | gofmt > tools.go go mod tidy -
Initialise gqlgen config and generate models
go run github.com/99designs/gqlgen init go mod tidy -
Start the graphql server
go run server.go
More help to get started:
- Getting started tutorial - a comprehensive guide to help you get started
- Real-world examples show how to create GraphQL applications
- Reference docs for the APIs
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.
We welcome contributions, Read our Contribution Guidelines to learn more about contributing to gqlgen
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;
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 aboveIf 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 generatedAfter 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, omittable: Boolean) 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)
}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 # a go integer
- github.com/99designs/gqlgen/graphql.ID # or a go string
- github.com/99designs/gqlgen/graphql.UintID # or a go uintThis 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.
These were added in v0.17.14 to allow accessing common interface fields without casting to a concrete type. However, certain fields, like Relay-style Connections, cannot be implemented with simple getters.
If you'd prefer to not have getters generated in your interfaces, you can add the following in your gqlgen.yml:
# gqlgen.yml
omit_getters: true