graphql

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Published: Sep 8, 2021 License: MIT Imports: 18 Imported by: 0

README

go-graphql-client

Preface: This is a fork of https://github.com/hasura/go-graphql-client that is a fork of https://github.com/shurcooL/graphql with extended features (subscription client, named operation).

The subscription client follows Apollo client specification https://github.com/apollographql/subscriptions-transport-ws/blob/master/PROTOCOL.md, using websocket protocol with https://github.com/nhooyr/websocket, a minimal and idiomatic WebSocket library for Go.

Package graphql provides a GraphQL client implementation.

For more information, see package github.com/shurcooL/githubv4, which is a specialized version targeting GitHub GraphQL API v4. That package is driving the feature development.

Status: In active early research and development. The API will change when opportunities for improvement are discovered; it is not yet frozen.

Installation

go-graphql-client requires Go version 1.13 or later.

go get -u github.com/diegosz/go-graphql-client

Usage

Construct a GraphQL client, specifying the GraphQL server URL. Then, you can use it to make GraphQL queries and mutations.

client := graphql.NewClient("https://example.com/graphql", nil)
// Use client...
Authentication

Some GraphQL servers may require authentication. The graphql package does not directly handle authentication. Instead, when creating a new client, you're expected to pass an http.Client that performs authentication. The easiest and recommended way to do this is to use the golang.org/x/oauth2 package. You'll need an OAuth token with the right scopes. Then:

import "golang.org/x/oauth2"

func main() {
	src := oauth2.StaticTokenSource(
		&oauth2.Token{AccessToken: os.Getenv("GRAPHQL_TOKEN")},
	)
	httpClient := oauth2.NewClient(context.Background(), src)

	client := graphql.NewClient("https://example.com/graphql", httpClient)
	// Use client...
Simple Query

To make a GraphQL query, you need to define a corresponding Go type.

For example, to make the following GraphQL query:

query {
	me {
		name
	}
}

You can define this variable:

var query struct {
	Me struct {
		Name graphql.String
	}
}

Then call client.Query, passing a pointer to it:

err := client.Query(context.Background(), &query, nil)
if err != nil {
	// Handle error.
}
fmt.Println(query.Me.Name)

// Output: Luke Skywalker
Arguments and Variables

Often, you'll want to specify arguments on some fields. You can use the graphql struct field tag for this.

For example, to make the following GraphQL query:

{
	human(id: "1000") {
		name
		height(unit: METER)
	}
}

You can define this variable:

var q struct {
	Human struct {
		Name   graphql.String
		Height graphql.Float `graphql:"height(unit: METER)"`
	} `graphql:"human(id: \"1000\")"`
}

Then call client.Query:

err := client.Query(context.Background(), &q, nil)
if err != nil {
	// Handle error.
}
fmt.Println(q.Human.Name)
fmt.Println(q.Human.Height)

// Output:
// Luke Skywalker
// 1.72

However, that'll only work if the arguments are constant and known in advance. Otherwise, you will need to make use of variables. Replace the constants in the struct field tag with variable names:

var q struct {
	Human struct {
		Name   graphql.String
		Height graphql.Float `graphql:"height(unit: $unit)"`
	} `graphql:"human(id: $id)"`
}

Then, define a variables map with their values:

variables := map[string]interface{}{
	"id":   graphql.ID(id),
	"unit": starwars.LengthUnit("METER"),
}

Finally, call client.Query providing variables:

err := client.Query(context.Background(), &q, variables)
if err != nil {
	// Handle error.
}
Inline Fragments

Some GraphQL queries contain inline fragments. You can use the graphql struct field tag to express them.

For example, to make the following GraphQL query:

{
	hero(episode: "JEDI") {
		name
		... on Droid {
			primaryFunction
		}
		... on Human {
			height
		}
	}
}

You can define this variable:

var q struct {
	Hero struct {
		Name  graphql.String
		Droid struct {
			PrimaryFunction graphql.String
		} `graphql:"... on Droid"`
		Human struct {
			Height graphql.Float
		} `graphql:"... on Human"`
	} `graphql:"hero(episode: \"JEDI\")"`
}

Alternatively, you can define the struct types corresponding to inline fragments, and use them as embedded fields in your query:

type (
	DroidFragment struct {
		PrimaryFunction graphql.String
	}
	HumanFragment struct {
		Height graphql.Float
	}
)

var q struct {
	Hero struct {
		Name          graphql.String
		DroidFragment `graphql:"... on Droid"`
		HumanFragment `graphql:"... on Human"`
	} `graphql:"hero(episode: \"JEDI\")"`
}

Then call client.Query:

err := client.Query(context.Background(), &q, nil)
if err != nil {
	// Handle error.
}
fmt.Println(q.Hero.Name)
fmt.Println(q.Hero.PrimaryFunction)
fmt.Println(q.Hero.Height)

// Output:
// R2-D2
// Astromech
// 0
Mutations

Mutations often require information that you can only find out by performing a query first. Let's suppose you've already done that.

For example, to make the following GraphQL mutation:

mutation($ep: Episode!, $review: ReviewInput!) {
	createReview(episode: $ep, review: $review) {
		stars
		commentary
	}
}
variables {
	"ep": "JEDI",
	"review": {
		"stars": 5,
		"commentary": "This is a great movie!"
	}
}

You can define:

var m struct {
	CreateReview struct {
		Stars      graphql.Int
		Commentary graphql.String
	} `graphql:"createReview(episode: $ep, review: $review)"`
}
variables := map[string]interface{}{
	"ep": starwars.Episode("JEDI"),
	"review": starwars.ReviewInput{
		Stars:      graphql.Int(5),
		Commentary: graphql.String("This is a great movie!"),
	},
}

Then call client.Mutate:

err := client.Mutate(context.Background(), &m, variables)
if err != nil {
	// Handle error.
}
fmt.Printf("Created a %v star review: %v\n", m.CreateReview.Stars, m.CreateReview.Commentary)

// Output:
// Created a 5 star review: This is a great movie!
Subcriptions

Usage

Construct a Subscription client, specifying the GraphQL server URL.

client := graphql.NewSubscriptionClient("wss://example.com/graphql")
defer client.Close()

// Subscribe subscriptions
// ...
// finally run the client
client.Run()
Subscribe

To make a GraphQL subscription, you need to define a corresponding Go type.

For example, to make the following GraphQL query:

subscription {
	me {
		name
	}
}

You can define this variable:

var subscription struct {
	Me struct {
		Name graphql.String
	}
}

Then call client.Subscribe, passing a pointer to it:

subscriptionId, err := client.Subscribe(&query, nil, func(dataValue *json.RawMessage, errValue error) error {
	if errValue != nil {
		// handle error
		// if returns error, it will failback to `onError` event
		return nil
	}
	data := query{}
	err := json.Unmarshal(dataValue, &data)

	fmt.Println(query.Me.Name)

	// Output: Luke Skywalker
})

if err != nil {
	// Handle error.
}

// you can unsubscribe the subscription while the client is running
client.Unsubscribe(subscriptionId)
Authentication

The subscription client is authenticated with GraphQL server through connection params:

client := graphql.NewSubscriptionClient("wss://example.com/graphql").
	WithConnectionParams(map[string]interface{}{
		"headers": map[string]string{
				"authentication": "...",
		},
	})

Options
client.
	//  write timeout of websocket client
	WithTimeout(time.Minute). 
	// When the websocket server was stopped, the client will retry connecting every second until timeout
	WithRetryTimeout(time.Minute).
	// sets loging function to print out received messages. By default, nothing is printed
	WithLog(log.Println).
	// max size of response message
	WithReadLimit(10*1024*1024).
	// these operation event logs won't be printed
	WithoutLogTypes(graphql.GQL_DATA, graphql.GQL_CONNECTION_KEEP_ALIVE)

Events
// OnConnected event is triggered when the websocket connected to GraphQL server sucessfully
client.OnConnected(fn func())

// OnDisconnected event is triggered when the websocket server was stil down after retry timeout
client.OnDisconnected(fn func())

// OnConnected event is triggered when there is any connection error. This is bottom exception handler level
// If this function is empty, or returns nil, the error is ignored
// If returns error, the websocket connection will be terminated
client.OnError(onError func(sc *SubscriptionClient, err error) error)
With operation name

Operation name is still on API decision plan https://github.com/shurcooL/graphql/issues/12. However, in my opinion separate methods are easier choice to avoid breaking changes

func (c *Client) NamedQuery(ctx context.Context, name string, q interface{}, variables map[string]interface{}) error

func (c *Client) NamedMutate(ctx context.Context, name string, q interface{}, variables map[string]interface{}) error

func (sc *SubscriptionClient) NamedSubscribe(name string, v interface{}, variables map[string]interface{}, handler func(message *json.RawMessage, err error) error) (string, error)
Raw bytes response

In the case we developers want to decode JSON response ourself. Moreover, the default UnmarshalGraphQL function isn't ideal with complicated nested interfaces

func (c *Client) QueryRaw(ctx context.Context, q interface{}, variables map[string]interface{}) (*json.RawMessage, error)

func (c *Client) MutateRaw(ctx context.Context, q interface{}, variables map[string]interface{}) (*json.RawMessage, error)

func (c *Client) NamedQueryRaw(ctx context.Context, name string, q interface{}, variables map[string]interface{}) (*json.RawMessage, error)

func (c *Client) NamedMutateRaw(ctx context.Context, name string, q interface{}, variables map[string]interface{}) (*json.RawMessage, error)

Directories

Path Synopsis
example/graphqldev graphqldev is a test program currently being used for developing graphql package.
ident Package ident provides functions for parsing and converting identifier names between various naming convention.
internal/jsonutil Package jsonutil provides a function for decoding JSON into a GraphQL query data structure.

References

License

Documentation

Overview

Package graphql provides a GraphQL client implementation.

For more information, see package github.com/shurcooL/githubv4, which is a specialized version targeting GitHub GraphQL API v4. That package is driving the feature development.

Status: In active early research and development. The API will change when opportunities for improvement are discovered; it is not yet frozen.

For now, see README for more details.

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func CustomWebsocketConnBuilder

func CustomWebsocketConnBuilder(options *websocket.DialOptions) (func(sc *SubscriptionClient) (WebsocketConn, error), error)

Types

type Boolean

type Boolean bool

Boolean represents true or false values.

func NewBoolean

func NewBoolean(v Boolean) *Boolean

NewBoolean is a helper to make a new *Boolean.

type Client

type Client struct {
	// contains filtered or unexported fields
}

Client is a GraphQL client.

func NewClient

func NewClient(url string, httpClient *http.Client) *Client

NewClient creates a GraphQL client targeting the specified GraphQL server URL. If httpClient is nil, then http.DefaultClient is used.

func (*Client) Mutate

func (c *Client) Mutate(ctx context.Context, m interface{}, variables map[string]interface{}) error

Mutate executes a single GraphQL mutation request, with a mutation derived from m, populating the response into it. m should be a pointer to struct that corresponds to the GraphQL schema.

func (*Client) MutateRaw

func (c *Client) MutateRaw(ctx context.Context, m interface{}, variables map[string]interface{}) (*json.RawMessage, error)

MutateRaw executes a single GraphQL mutation request, with a mutation derived from m, populating the response into it. m should be a pointer to struct that corresponds to the GraphQL schema. return raw bytes message.

func (*Client) NamedMutate

func (c *Client) NamedMutate(ctx context.Context, name string, m interface{}, variables map[string]interface{}) error

NamedMutate executes a single GraphQL mutation request, with operation name

func (*Client) NamedMutateRaw

func (c *Client) NamedMutateRaw(ctx context.Context, name string, m interface{}, variables map[string]interface{}) (*json.RawMessage, error)

NamedMutateRaw executes a single GraphQL mutation request, with operation name return raw bytes message.

func (*Client) NamedQuery

func (c *Client) NamedQuery(ctx context.Context, name string, q interface{}, variables map[string]interface{}) error

NamedQuery executes a single GraphQL query request, with operation name

func (*Client) NamedQueryRaw

func (c *Client) NamedQueryRaw(ctx context.Context, name string, q interface{}, variables map[string]interface{}) (*json.RawMessage, error)

NamedQueryRaw executes a single GraphQL query request, with operation name return raw bytes message.

func (*Client) Query

func (c *Client) Query(ctx context.Context, q interface{}, variables map[string]interface{}) error

Query executes a single GraphQL query request, with a query derived from q, populating the response into it. q should be a pointer to struct that corresponds to the GraphQL schema.

func (*Client) QueryRaw

func (c *Client) QueryRaw(ctx context.Context, q interface{}, variables map[string]interface{}) (*json.RawMessage, error)

Query executes a single GraphQL query request, with a query derived from q, populating the response into it. q should be a pointer to struct that corresponds to the GraphQL schema. return raw bytes message.

type Float

type Float float64

Float represents signed double-precision fractional values as specified by IEEE 754.

func NewFloat

func NewFloat(v Float) *Float

NewFloat is a helper to make a new *Float.

type ID

type ID interface{}

ID represents a unique identifier that is Base64 obfuscated. It is often used to refetch an object or as key for a cache. The ID type appears in a JSON response as a String; however, it is not intended to be human-readable. When expected as an input type, any string (such as "VXNlci0xMA==") or integer (such as 4) input value will be accepted as an ID.

func NewID

func NewID(v ID) *ID

NewID is a helper to make a new *ID.

type Int

type Int int32

Int represents non-fractional signed whole numeric values. Int can represent values between -(2^31) and 2^31 - 1.

func NewInt

func NewInt(v Int) *Int

NewInt is a helper to make a new *Int.

type OperationMessage

type OperationMessage struct {
	ID      string               `json:"id,omitempty"`
	Type    OperationMessageType `json:"type"`
	Payload json.RawMessage      `json:"payload,omitempty"`
}

func (OperationMessage) String

func (om OperationMessage) String() string

type OperationMessageType

type OperationMessageType string

OperationMessageType

const (
	// Client sends this message after plain websocket connection to start the communication with the server
	GQL_CONNECTION_INIT OperationMessageType = "connection_init"
	// The server may responses with this message to the GQL_CONNECTION_INIT from client, indicates the server rejected the connection.
	GQL_CONNECTION_ERROR OperationMessageType = "conn_err"
	// Client sends this message to execute GraphQL operation
	GQL_START OperationMessageType = "start"
	// Client sends this message in order to stop a running GraphQL operation execution (for example: unsubscribe)
	GQL_STOP OperationMessageType = "stop"
	// Server sends this message upon a failing operation, before the GraphQL execution, usually due to GraphQL validation errors (resolver errors are part of GQL_DATA message, and will be added as errors array)
	GQL_ERROR OperationMessageType = "error"
	// The server sends this message to transfter the GraphQL execution result from the server to the client, this message is a response for GQL_START message.
	GQL_DATA OperationMessageType = "data"
	// Server sends this message to indicate that a GraphQL operation is done, and no more data will arrive for the specific operation.
	GQL_COMPLETE OperationMessageType = "complete"
	// Server message that should be sent right after each GQL_CONNECTION_ACK processed and then periodically to keep the client connection alive.
	// The client starts to consider the keep alive message only upon the first received keep alive message from the server.
	GQL_CONNECTION_KEEP_ALIVE OperationMessageType = "ka"
	// The server may responses with this message to the GQL_CONNECTION_INIT from client, indicates the server accepted the connection. May optionally include a payload.
	GQL_CONNECTION_ACK OperationMessageType = "connection_ack"
	// Client sends this message to terminate the connection.
	GQL_CONNECTION_TERMINATE OperationMessageType = "connection_terminate"
	// Unknown operation type, for logging only
	GQL_UNKNOWN OperationMessageType = "unknown"
	// Internal status, for logging only
	GQL_INTERNAL OperationMessageType = "internal"
)

type String

type String string

String represents textual data as UTF-8 character sequences. This type is most often used by GraphQL to represent free-form human-readable text.

func NewString

func NewString(v String) *String

NewString is a helper to make a new *String.

type SubscriptionClient

type SubscriptionClient struct {
	// contains filtered or unexported fields
}

SubscriptionClient is a GraphQL subscription client.

func NewSubscriptionClient

func NewSubscriptionClient(url string) *SubscriptionClient

func (*SubscriptionClient) Close

func (sc *SubscriptionClient) Close() (err error)

Close closes all subscription channel and websocket as well

func (*SubscriptionClient) GetContext

func (sc *SubscriptionClient) GetContext() context.Context

GetContext returns current context of subscription client

func (*SubscriptionClient) GetTimeout

func (sc *SubscriptionClient) GetTimeout() time.Duration

GetContext returns write timeout of websocket client

func (*SubscriptionClient) GetURL

func (sc *SubscriptionClient) GetURL() string

GetURL returns GraphQL server's URL

func (*SubscriptionClient) NamedSubscribe

func (sc *SubscriptionClient) NamedSubscribe(name string, v interface{}, variables map[string]interface{}, handler func(message *json.RawMessage, err error) error) (string, error)

NamedSubscribe sends start message to server and open a channel to receive data, with operation name

func (*SubscriptionClient) OnConnected

func (sc *SubscriptionClient) OnConnected(fn func()) *SubscriptionClient

OnConnected event is triggered when the websocket connected to GraphQL server sucessfully

func (*SubscriptionClient) OnDisconnected

func (sc *SubscriptionClient) OnDisconnected(fn func()) *SubscriptionClient

OnDisconnected event is triggered when the websocket server was stil down after retry timeout

func (*SubscriptionClient) OnError

func (sc *SubscriptionClient) OnError(onError func(sc *SubscriptionClient, err error) error) *SubscriptionClient

OnConnected event is triggered when there is any connection error. This is bottom exception handler level If this function is empty, or returns nil, the error is ignored If returns error, the websocket connection will be terminated

func (*SubscriptionClient) Reset

func (sc *SubscriptionClient) Reset() error

Reset restart websocket connection and subscriptions

func (*SubscriptionClient) Run

func (sc *SubscriptionClient) Run() error

Run start websocket client and subscriptions. If this function is run with goroutine, it can be stopped after closed

func (*SubscriptionClient) Subscribe

func (sc *SubscriptionClient) Subscribe(v interface{}, variables map[string]interface{}, handler func(message *json.RawMessage, err error) error) (string, error)

Subscribe sends start message to server and open a channel to receive data. The handler callback function will receive raw message data or error. If the call return error, onError event will be triggered The function returns subscription ID and error. You can use subscription ID to unsubscribe the subscription

func (*SubscriptionClient) Unsubscribe

func (sc *SubscriptionClient) Unsubscribe(id string) error

Unsubscribe sends stop message to server and close subscription channel The input parameter is subscription ID that is returned from Subscribe function

func (*SubscriptionClient) WithConnectionParams

func (sc *SubscriptionClient) WithConnectionParams(params map[string]interface{}) *SubscriptionClient

WithConnectionParams updates connection params for sending to server through GQL_CONNECTION_INIT event It's usually used for authentication handshake

func (*SubscriptionClient) WithLog

func (sc *SubscriptionClient) WithLog(logger func(args ...interface{})) *SubscriptionClient

WithLog sets loging function to print out received messages. By default, nothing is printed

func (*SubscriptionClient) WithReadLimit

func (sc *SubscriptionClient) WithReadLimit(limit int64) *SubscriptionClient

WithReadLimit set max size of response message

func (*SubscriptionClient) WithRetryTimeout

func (sc *SubscriptionClient) WithRetryTimeout(timeout time.Duration) *SubscriptionClient

WithRetryTimeout updates reconnecting timeout. When the websocket server was stopped, the client will retry connecting every second until timeout

func (*SubscriptionClient) WithTimeout

func (sc *SubscriptionClient) WithTimeout(timeout time.Duration) *SubscriptionClient

WithTimeout updates write timeout of websocket client

func (*SubscriptionClient) WithWebSocket

func (sc *SubscriptionClient) WithWebSocket(fn func(sc *SubscriptionClient) (WebsocketConn, error)) *SubscriptionClient

WithWebSocket replaces customized websocket client constructor In default, subscription client uses https://github.com/nhooyr/websocket

func (*SubscriptionClient) WithoutLogTypes

func (sc *SubscriptionClient) WithoutLogTypes(types ...OperationMessageType) *SubscriptionClient

WithoutLogTypes these operation types won't be printed

type WebsocketConn

type WebsocketConn interface {
	ReadJSON(v interface{}) error
	WriteJSON(v interface{}) error
	Close() error
	// SetReadLimit sets the maximum size in bytes for a message read from the peer. If a
	// message exceeds the limit, the connection sends a close message to the peer
	// and returns ErrReadLimit to the application.
	SetReadLimit(limit int64)
}

WebsocketHandler abstracts WebSocket connecton functions ReadJSON and WriteJSON data of a frame from the WebSocket connection. Close the WebSocket connection.

Directories

Path Synopsis
example
graphqldev
graphqldev is a test program currently being used for developing graphql package.
graphqldev is a test program currently being used for developing graphql package.
subscription
subscription is a test program currently being used for developing graphql package.
subscription is a test program currently being used for developing graphql package.
Package ident provides functions for parsing and converting identifier names between various naming convention.
Package ident provides functions for parsing and converting identifier names between various naming convention.
internal
jsonutil
Package jsonutil provides a function for decoding JSON into a GraphQL query data structure.
Package jsonutil provides a function for decoding JSON into a GraphQL query data structure.

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