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package gqlclient
import (
"bytes"
"context"
"encoding/json"
"fmt"
"io"
"mime"
"net/http"
)
// Client is a GraphQL HTTP client.
type Client struct {
endpoint string
http *http.Client
}
// New creates a new GraphQL client with the specified endpoint.
//
// If hc is nil, http.DefaultClient is used.
func New(endpoint string, hc *http.Client) *Client {
if hc == nil {
hc = http.DefaultClient
}
return &Client{
endpoint: endpoint,
http: hc,
}
}
// Operation describes a GraphQL operation.
//
// An operation is a query with variables.
type Operation struct {
query string
vars map[string]interface{}
uploads map[string]Upload
}
// NewOperation creates a new GraphQL operation.
func NewOperation(query string) *Operation {
return &Operation{query: query}
}
// Var defines a new variable.
//
// If the variable is already defined, Var panics.
func (op *Operation) Var(k string, v interface{}) {
if op.vars == nil {
op.vars = make(map[string]interface{})
op.uploads = make(map[string]Upload)
}
if _, ok := op.vars[k]; ok {
panic(fmt.Sprintf("gqlclient: called Operation.Var twice on %q", k))
}
op.vars[k] = v
// TODO: support more deeply nested uploads
switch v := v.(type) {
case Upload:
op.uploads[k] = v
case *Upload:
if v != nil {
op.uploads[k] = *v
}
case []Upload:
for i, upload := range v {
upload := upload // copy
op.uploads[fmt.Sprintf("%v.%v", k, i)] = upload
}
case []*Upload:
for i, upload := range v {
if upload != nil {
op.uploads[fmt.Sprintf("%v.%v", k, i)] = *upload
}
}
}
}
// Execute sends the operation to the GraphQL server.
//
// The data returned by the server will be decoded into the data argument.
func (c *Client) Execute(ctx context.Context, op *Operation, data interface{}) error {
reqData := struct {
Query string `json:"query"`
Vars map[string]interface{} `json:"variables"`
}{
Query: op.query,
Vars: op.vars,
}
var reqBuf bytes.Buffer
if err := json.NewEncoder(&reqBuf).Encode(&reqData); err != nil {
return fmt.Errorf("failed to encode request payload: %v", err)
}
var reqBody io.Reader
var contentType string
if len(op.uploads) > 0 {
pr, pw := io.Pipe()
defer pr.Close()
reqBody = pr
contentType = writeMultipart(pw, op.uploads, &reqBuf)
} else {
reqBody = &reqBuf
contentType = "application/json; charset=utf-8"
}
// io.TeeReader(reqBody, os.Stderr)
req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.endpoint, reqBody)
if err != nil {
return fmt.Errorf("failed to create HTTP request: %v", err)
}
req.Header.Set("Content-Type", contentType)
req.Header.Set("Accept", "application/json")
resp, err := c.http.Do(req)
if err != nil {
return fmt.Errorf("HTTP request failed: %v", err)
}
defer resp.Body.Close()
contentType = resp.Header.Get("Content-Type")
if contentType == "" {
contentType = "text/plain"
}
mediaType, _, err := mime.ParseMediaType(contentType)
if err != nil {
return fmt.Errorf("invalid Content-Type %q: %v", contentType, err)
} else if mediaType != "application/json" {
if resp.StatusCode/100 != 2 {
return &HTTPError{
StatusCode: resp.StatusCode,
statusText: resp.Status,
}
}
return fmt.Errorf("invalid Content-Type %q: expected application/json", contentType)
}
respData := struct {
Data interface{}
Errors []Error
}{Data: data}
// io.TeeReader(resp.Body, os.Stderr)
if err := json.NewDecoder(resp.Body).Decode(&respData); err != nil {
return fmt.Errorf("failed to decode response payload: %v", err)
}
if len(respData.Errors) > 0 {
err = joinErrors(respData.Errors)
}
if resp.StatusCode/100 != 2 {
err = &HTTPError{
StatusCode: resp.StatusCode,
statusText: resp.Status,
err: err,
}
}
return err
}
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