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graphql.go
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graphql.go
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package graphql
import (
"bytes"
"context"
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
"github.com/Laisky/graphql/internal/jsonutil"
)
func defaultClientHeaders() map[string]string {
return map[string]string{
"Content-Type": "application/json",
}
}
// ClientOptFunc graphql client option
type ClientOptFunc func(*Client)
// WithHeader set graphql client header
func WithHeader(key, val string) ClientOptFunc {
return func(c *Client) {
c.headers[key] = val
}
}
// WithCookie set graphql client cookie
func WithCookie(key, val string) ClientOptFunc {
return func(c *Client) {
if c.cookies == nil {
c.cookies = map[string]string{}
}
c.cookies[key] = val
}
}
// Client is a GraphQL client.
type Client struct {
url string // GraphQL server URL.
httpClient *http.Client
headers,
cookies map[string]string
}
// NewClient creates a GraphQL client targeting the specified GraphQL server URL.
// If httpClient is nil, then http.DefaultClient is used.
func NewClient(url string, httpClient *http.Client, opts ...ClientOptFunc) (c *Client) {
if httpClient == nil {
httpClient = http.DefaultClient
}
c = &Client{
headers: defaultClientHeaders(),
url: url,
httpClient: httpClient,
}
for _, optf := range opts {
optf(c)
}
return c
}
// 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 (c *Client) Query(ctx context.Context, q interface{}, variables map[string]interface{}) error {
return c.do(ctx, queryOperation, q, variables)
}
// 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 (c *Client) Mutate(ctx context.Context, m interface{}, variables map[string]interface{}) error {
return c.do(ctx, mutationOperation, m, variables)
}
// do executes a single GraphQL operation.
func (c *Client) do(ctx context.Context, op operationType, v interface{}, variables map[string]interface{}) (err error) {
var query string
switch op {
case queryOperation:
query = constructQuery(v, variables)
case mutationOperation:
query = constructMutation(v, variables)
default:
return fmt.Errorf("unknown operationType, got %v", op)
}
var (
req *http.Request
resp *http.Response
)
switch op {
case queryOperation:
if req, err = http.NewRequest("GET", c.url, nil); err != nil {
return err
}
var buf bytes.Buffer
err := json.NewEncoder(&buf).Encode(variables)
if err != nil {
return err
}
q := req.URL.Query()
q.Add("query", query)
q.Add("variables", buf.String())
req.URL.RawQuery = q.Encode()
case mutationOperation:
in := struct {
Query string `json:"query"`
Variables map[string]interface{} `json:"variables,omitempty"`
}{
Query: query,
Variables: variables,
}
var buf bytes.Buffer
err := json.NewEncoder(&buf).Encode(in)
if err != nil {
return err
}
if req, err = http.NewRequest("POST", c.url, &buf); err != nil {
return err
}
}
// set cookies and headers
var k, val string
for k, val = range c.headers {
req.Header.Set(k, val)
}
for k, val = range c.cookies {
req.AddCookie(&http.Cookie{Name: k, Value: val})
}
if resp, err = c.httpClient.Do(req.WithContext(ctx)); err != nil {
return err
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
body, _ := ioutil.ReadAll(resp.Body)
return fmt.Errorf("non-200 OK status code: %v body: %q", resp.Status, body)
}
var out struct {
Data *json.RawMessage
Errors Errors
//Extensions interface{} // Unused.
}
err = json.NewDecoder(resp.Body).Decode(&out)
if err != nil {
// TODO: Consider including response body in returned error, if deemed helpful.
return err
}
if out.Data != nil {
err := jsonutil.UnmarshalGraphQL(*out.Data, v)
if err != nil {
// TODO: Consider including response body in returned error, if deemed helpful.
return err
}
}
if len(out.Errors) > 0 {
return out.Errors
}
return nil
}
// Errors represents the "errors" array in a response from a GraphQL server.
// If returned via error interface, the slice is expected to contain at least 1 element.
//
// Specification: https://facebook.github.io/graphql/#sec-Errors.
type Errors []struct {
Message string
Locations []struct {
Line int
Column int
}
Extensions interface{}
}
// Error implements error interface.
func (e Errors) Error() string {
return e[0].Message
}
type operationType uint8
const (
queryOperation operationType = iota
mutationOperation
//subscriptionOperation // Unused.
)