dgraph-lambda-go

Go Library written to build Dgraph Lambda servers as an alternative to the Dgraph JS Lambda Server

Getting started

• To install dgraph-lambda-go run the command go get github.com/schartey/dgraph-lambda-go in your project directory.
• Then initialize the project by running go run github.com/schartey/dgraph-lambda-go init.

Implement resolver functions and middleware

On startup this library provides a resolver.

err := api.RunServer(func(r *resolver.Resolver, gql *graphql.Client, dql *dgo.Dgraph) {

})

Within this startup function you can provide resolver functions and middleware. It's best to first define the input and output structs for the resolver. For example CreateUserInput and UserData struct

type CreateUserInput struct {
	Username string `json:"username"`
}

type UserData struct {
	Id              string `json:"id"`
	Username        string `json:"username"`
	ComplexProperty string `json:"complexProperty"`
}

Then you can provide a resolver for fields, queries and mutations like this

// Field Resolver
r.ResolveFunc("UserData.complexProperty", func(ctx context.Context, input []byte, parents []byte, ah resolver.AuthHeader) (interface{}, error) {
    var userParents []UserData
    json.Unmarshal(parents, &userParents)

    var complexProperties []string
    for _, userParent := range userParents {
        complexProperties = append(complexProperties, fmt.Sprintf("VeryComplex - %s", userParent.Id))
    }

    return complexProperties, nil
})

// Query/Mutation Resolver
r.ResolveFunc("Mutation.createUser", func(ctx context.Context, input []byte, parents []byte, ah resolver.AuthHeader) (interface{}, error) {
    var createUserInput CreateUserInput
    json.Unmarshal(input, &createUserInput)

    // Do Something
    user := UserData{
        Id:       "0x1",
        Username: createUserInput.Username,
    }
    return user, nil
})

You can also provide global middleware, as well as middleware on specific resolvers

r.Use(func(hf resolver.HandlerFunc) resolver.HandlerFunc {
    return func(c context.Context, b []byte, parents []byte, ah resolver.AuthHeader) (interface{}, error) {
        // Authorization.
        // Add user to context
        return hf(c, b, parents, ah)
    }
})

r.UseOnResolver("Mutation.createUser", func(hf resolver.HandlerFunc) resolver.HandlerFunc {
    return func(c context.Context, b []byte, parents []byte, ah resolver.AuthHeader) (interface{}, error) {
        // Validation .
        return b, nil
    }
})

Finally a webhook resolver is also provided on Types

r.WebHookFunc("UserData", func(ctx context.Context, event resolver.Event) error {
    // Send E-Mail
    return nil
})

Additionally a graphql and dql client connected to the dgraph server are provided, so you can query and make changes to the databases.

Examples

Additional examples will be provided in the examples module