https://github.com/nuuday/gqlappsync
https://github.com/nuuday/gqlappsync
Last synced: 4 months ago
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- Host: GitHub
- URL: https://github.com/nuuday/gqlappsync
- Owner: nuuday
- License: mit
- Created: 2022-09-14T09:15:05.000Z (over 2 years ago)
- Default Branch: main
- Last Pushed: 2024-06-12T22:55:22.000Z (12 months ago)
- Last Synced: 2024-12-30T07:15:24.303Z (5 months ago)
- Language: Go
- Size: 34.2 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# GqlAppSync
## Description
GqlAppSync is a code-generating tool built on top of [gqlgen](https://github.com/99designs/gqlgen), where the server and resolvers have been removed.
It was created to add strongly-typed models for [AWS AppSync](https://aws.amazon.com/appsync/).
## Quick start
1. Get the latest version of GqlAppSync
`go get github.com/nuuday/gqlappsync`
2. Define a `schema.graphql` file.
E.g.:
```graphql
type Book {
title: String!
author: Author!
}
type Query {
books: [Book!]!
}
type Author {
name: String!
}
```
**Note:** Doesn't currently support underscore in type names
3. Define a `gqlgen.yml` file.
E.g.:
```yaml
# gqlgen.yml
# Where are all the schema file located?
schema:
- ./schema.graphql
# Where should any generated models go?
model:
filename: ./generated/models.gen.go
package: generated
# This section declares type mapping between the GraphQL and go type systems
#
# The first line in each type will be used as defaults for resolver arguments and
# modelgen, the others will be allowed when binding to fields. Configure them to
# your liking
models:
ID:
model:
- github.com/99designs/gqlgen/graphql.ID
- github.com/99designs/gqlgen/graphql.Int
- github.com/99designs/gqlgen/graphql.Int64
- github.com/99designs/gqlgen/graphql.Int32
Int:
model:
- github.com/99designs/gqlgen/graphql.Int
- github.com/99designs/gqlgen/graphql.Int64
- github.com/99designs/gqlgen/graphql.Int32
AWSDateTime:
model:
- github.com/99designs/gqlgen/graphql.Time
```
4. Generate models
`go run github.com/nuuday/gqlappsync`
The `--config 'path'` flag can be added to specify the path to the `gqlgen.yml`-filename
5. Import and use the models in the lambdas
```go
package main
import (
"context"
"todo/generated" // reference to the generated models
"github.com/aws/aws-lambda-go/lambda"
)
func handler(ctx context.Context) ([]generated.Book, error) {
books := []generated.Book{
{
Title: "Clean Code",
Author: &generated.Author{
Name: "Robert Cecil Martin",
},
},
{
Title: "The Pragmatic Programmer",
Author: &generated.Author{
Name: "Andy Hunt and Dave Thomas",
},
},
}
return books, nil
}
func main() {
lambda.Start(handler)
}
```
## Working with interfaces and unions in AppSync and Go
Appsync can't differentiate between interface implementations or unions unless the __typename field is provided with the name of the type.
Therefore all graphql types that implement an interface or are part of a union will have a Typename field generated with a `json:"__typename"`-tag. Currently, Go doesn't support custom default values, so the Typename field has to be assigned through the `SetTypenameRecursively(x)`method.
```go
package main
import (
"context"
"todo/generated" // reference to the generated models
"github.com/aws/aws-lambda-go/lambda"
)
func handler(ctx context.Context) ([]generated.Book, error) {
books := []generated.Book{ // Book is an interface
generated.TextBook{// Textbook is an implementation of the interface
Title: "Clean Code",
Author: &generated.Author{
Name: "Robert Cecil Martin",
},
SupplementaryMaterial: []generated.MediaItem{
generated.AudioClip{
Duration: 120,
}
},
}
}
return generated.SetTypenameRecursively(books), nil // This is required for Appsync to know which type is being returned.
}
func main() {
lambda.Start(handler)
}
```
### Tip: Middleware
If the handler returns an interface that is implemented by a number of types that each would require invoking the `SetTypenameRecursively(x)`method, you could instead move the invocation to a lambda middleware.
```go
func handler(ctx context.Context) (generated.Book, error) {
if foo {
return generated.Textbook{...}, nil
}
return generated.CookingBook{...}, nil
}
type handlerFunc func(context.Context) (generated.Book, error)
func SetTypename(f handlerFunc) handlerFunc {
return func(ctx context.Context) (generated.Book, error) {
response, err := f(ctx)
response = generated.SetTypenameRecursively(response) // The invocation
return response, err
}
}
func main() {
lambda.Start(SetTypename(handler))
}
```