dgraph-lambda-go

dgraph-lambda-go

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

It is currently in heavy development! Please create an issue if something does not work correctly.

Getting started

• Create project go mod init
• 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.
• Set path to your graphql schema in lambda.yaml
• Generate types and resolvers go run github.com/schartey/dgraph-lambda-go generate

Configuration

When first initializing the lambda server it will generate a basic lambda.yaml file with the following configuration:

schema:
  - ../trendgraph/dgraph/*.graphql

exec:
  filename: lambda/generated/generated.go
  package: generated

model:
  filename: lambda/model/models_gen.go
  package: model

autobind:
  - "github.com/schartey/dgraph-lambda-go/examples/models"

resolver:
  dir: lambda/resolvers
  package: resolvers
  filename_template: "{resolver}.resolver.go" # also allow "{name}.resolvers.go"

server:
  standalone: true

Schema

A list of graphql schema files using glob. This is probably only one file when using DGraph.

Exec

This option allows you to select a file path where generated code should go that should NOT be edited.

Model

This option allows you to define a file path where the generated models should be placed.

Autobind

You might have some predefined models already. Here you can define a list of packages in which models can be found that should be used instead of generating them.

Resolver

Define a folder and package name for the generated resolvers. The filename_template can currently only be {resolver}.resolver.go, but I want to allow resolver generation based on name as well in the future. Using {resolver}.resolver.go will generate a fieldResolver.go, queryResolver.go, mutationResolver.go, webhookResolver.go and middlewareResolver.go file where each type of resolver will reside in.

Server

On initialization a server.go file is generated from which you can start the server. With standalone set to false you can add custom routes to the http server.

Generating resolvers

This framework is able to generate field, query, mutation and webhook resolvers. These will automatically be detected in the graphql schema file. To generate middleware you have to use comments within the schema. For example:

Type Fields:

type User @lambdaOnMutate(add: true, update: true, delete: true) {
    id: ID!
    username: String!
    """
    @middleware(["auth"])
    """
    secret: string @lambda
}

Queries

type Query {
    """
    @middleware(["auth"])
    """
    randomUser(seed: String): User @lambda
}

Mutations

type Mutation {
    """
    @middleware(["auth"])
    """
    createUser(input: CreateUserInput!): User @lambda
}

Implementing resolvers

Here are implementations from the above mentioned schema examples.

Field Resolver

func (f *FieldResolver) User_secret(ctx context.Context, parents []string, authHeader api.AuthHeader) ([]string, error) { 
	var secrets []string
    for _, userParent := range userParents {
        secrets = append(secrets, fmt.Sprintf("Secret - %s", userParent.Id))
    }
    return secrets, nil
}

Query Resolver

func (q *QueryResolver) Query_randomUser(ctx context.Context, seed string, authHeader api.AuthHeader) (*model.User, error) { 
	nameGenerator := namegenerator.NewNameGenerator(seed)
    name := nameGenerator.Generate()

    user := &model.User{
        Id:       "0x1",
        Username: name,
    }
    return user, nil
}

Mutation Resolver

func (q *MutationResolver) Mutation_createUser(ctx context.Context, input *model.CreateUserInput, authHeader api.AuthHeader) (*model.User, error) {
    user := &User{
        Id:       "0x1",
        Username: createUserInput.Username,
    }
	return user, nil
}

Webhook Resolver

func (w *WebhookResolver) Webhook_User(ctx context.Context, event api.Event) error {
    // Send Email
	return nil
}

Middleware Resolver

func (m *MiddlewareResolver) Middleware_auth(md *api.MiddlewareData) error {
    // Check Token
    valid := true //false
    if valid {
    	md.Ctx = context.WithValue(md.Ctx, "logged_in", "true")
        return nil
    } else {
        return errors.New("Token invalid!")
    }
}

Examples

Additional examples will be provided in the examples module