forked from shurcooL/graphql
/
graphql.go
140 lines (125 loc) · 4.27 KB
/
graphql.go
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package graphql
import (
"bytes"
"context"
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
"golang.org/x/net/context/ctxhttp"
)
//go:generate mockgen -destination=./mock/graphql.go -package=mock . GraphQL
type GraphQL interface {
QueryString(ctx context.Context, q string, variables map[string]interface{}, v interface{}) error
Query(ctx context.Context, q interface{}, variables map[string]interface{}) error
Mutate(ctx context.Context, m interface{}, variables map[string]interface{}) error
MutateString(ctx context.Context, m string, variables map[string]interface{}, v interface{}) error
}
// Client is a GraphQL client.
type Client struct {
url string // GraphQL server URL.
httpClient *http.Client
}
// 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) *Client {
if httpClient == nil {
httpClient = http.DefaultClient
}
return &Client{
url: url,
httpClient: httpClient,
}
}
// QueryString executes a single GraphQL query request,
// using the given raw query `q` and populating the response into the `v`.
// `q` should be a correct GraphQL query request string that corresponds to the GraphQL schema.
func (c *Client) QueryString(ctx context.Context, q string, variables map[string]interface{}, v interface{}) error {
return c.do(ctx, q, variables, v)
}
// 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 {
query := constructQuery(q, variables)
return c.do(ctx, query, variables, q)
}
// 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 {
query := constructMutation(m, variables)
return c.do(ctx, query, variables, m)
}
// MutateString executes a single GraphQL mutation request,
// using the given raw query `m` and populating the response into it.
// `m` should be a correct GraphQL mutation request string that corresponds to the GraphQL schema.
func (c *Client) MutateString(ctx context.Context, m string, variables map[string]interface{}, v interface{}) error {
return c.do(ctx, m, variables, v)
}
// do executes a single GraphQL operation.
func (c *Client) do(ctx context.Context, query string, variables map[string]interface{}, v interface{}) error {
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
}
resp, err := ctxhttp.Post(ctx, c.httpClient, c.url, "application/json", &buf)
if 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 := json.Unmarshal(*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
}
}
// Error implements error interface.
func (e errors) Error() string {
return e[0].Message
}
type operationType uint8
const (
queryOperation operationType = iota
mutationOperation
// subscriptionOperation // Unused.
)