Handler.go

handler.go

@@ -0,0 +1,164 @@
+package handler
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"github.com/playlyfe/go-graphql"
+
+	"golang.org/x/net/context"
+)
+
+//Shortcuts for the Content-Type header
+const (
+	ContentTypeJSON           = "application/json"
+	ContentTypeGraphQL        = "application/graphql"
+	ContentTypeFormURLEncoded = "application/x-www-form-urlencoded"
+)
+
+//Handler structure
+type Handler struct {
+	Executor *graphql.Executor
+	Context  interface{}
+	Pretty   bool
+}
+
+//RequestParameters from query like " /graphql?query=getUser($id:ID){lastName}&variables={"id":"4"} "
+type RequestParameters struct {
+	Query         string                 `json:"query" url:"query" schema:"query"`
+	Variables     map[string]interface{} `json:"variables" url:"variables" schema:"variables"`
+	OperationName string                 `json:"operationName" url:"operationName" schema:"operationName"`
+}
+
+//RequestParametersCompatibility represents an workaround for getting`variables` as a JSON string
+type RequestParametersCompatibility struct {
+	Query         string `json:"query" url:"query" schema:"query"`
+	Variables     string `json:"variables" url:"variables" schema:"variables"`
+	OperationName string `json:"operationName" url:"operationName" schema:"operationName"`
+}
+
+func getFromURL(values url.Values) *RequestParameters {
+	if values.Get("query") != "" {
+		// get variables map
+		var variables map[string]interface{}
+		variablesStr := values.Get("variables")
+		json.Unmarshal([]byte(variablesStr), variables)
+
+		return &RequestParameters{
+			Query:         values.Get("query"),
+			Variables:     variables,
+			OperationName: values.Get("operationName"),
+		}
+	}
+
+	return nil
+}
+
+// NewRequestParameters Parses a http.Request into GraphQL request options struct
+func NewRequestParameters(r *http.Request) *RequestParameters {
+	if reqParams := getFromURL(r.URL.Query()); reqParams != nil {
+		return reqParams
+	}
+
+	if r.Method != "POST" {
+		return &RequestParameters{}
+	}
+
+	if r.Body == nil {
+		return &RequestParameters{}
+	}
+
+	// TODO: improve Content-Type handling
+	contentTypeStr := r.Header.Get("Content-Type")
+	contentTypeTokens := strings.Split(contentTypeStr, ";")
+	contentType := contentTypeTokens[0]
+
+	switch contentType {
+	case ContentTypeGraphQL:
+		body, err := ioutil.ReadAll(r.Body)
+		if err != nil {
+			return &RequestParameters{}
+		}
+		return &RequestParameters{
+			Query: string(body),
+		}
+	case ContentTypeFormURLEncoded:
+		if err := r.ParseForm(); err != nil {
+			return &RequestParameters{}
+		}
+
+		if reqParams := getFromURL(r.PostForm); reqParams != nil {
+			return reqParams
+		}
+
+		return &RequestParameters{}
+
+	case ContentTypeJSON:
+		fallthrough
+	default:
+		var params RequestParameters
+		body, err := ioutil.ReadAll(r.Body)
+		if err != nil {
+			return &params
+		}
+		err = json.Unmarshal(body, &params)
+		if err != nil {
+			// Probably `variables` was sent as a string instead of an object.
+			// So, we try to be polite and try to parse that as a JSON string
+			var CompatibleParams RequestParametersCompatibility
+			json.Unmarshal(body, &CompatibleParams)
+			json.Unmarshal([]byte(CompatibleParams.Variables), &params.Variables)
+		}
+		return &params
+	}
+}
+
+// ContextHandler provides an entrypoint into executing graphQL queries with a
+// user-provided context.
+func (h *Handler) ContextHandler(ctx context.Context, w http.ResponseWriter, r *http.Request) {
+	// get query
+	params := NewRequestParameters(r)
+	// execute graphql query
+	result, _ := (h.Executor).Execute(h.Context, params.Query, params.Variables, params.OperationName)
+
+	if h.Pretty {
+		w.WriteHeader(200) //http.StatusOK = 200
+		buff, _ := json.MarshalIndent(result, "", "   ")
+		w.Write(buff)
+	} else {
+		w.WriteHeader(200) //http.StatusOK = 200
+		buff, _ := json.Marshal(result)
+		w.Write(buff)
+	}
+}
+
+// ServeHTTP provides an entrypoint into executing graphQL queries.
+func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	h.ContextHandler(context.Background(), w, r)
+}
+
+//Config for handler of the schema
+type Config Handler
+
+//New config
+func New(c *Config) *Handler {
+	if c == nil {
+		c = &Config{
+			Executor: nil,
+			Context:  "",
+			Pretty:   true,
+		}
+	}
+	if c.Executor == nil {
+		panic("Undefined GraphQL Executor")
+	}
+
+	return &Handler{
+		Executor: c.Executor,
+		Context:  c.Context,
+		Pretty:   c.Pretty,
+	}
+}