fix(GraphQL): fix bug in custom resolver, now body need not have all the fields.

graphql/e2e/custom_logic/custom_logic_test.go

@@ -1012,6 +1012,49 @@ func TestCustomFieldsShouldForwardHeaders(t *testing.T) {
 	require.Nilf(t, result.Errors, "%+v", result.Errors)
 }
 
+func TestCustomFieldsShouldSkipNonEmptyVariable(t *testing.T) {
+	schema := `
+    type User {
+		id: ID!
+        address:String
+		name: String
+			@custom(
+				http: {
+					url: "http://mock:8888/userName"
+					method: "GET"
+					body: "{uid: $id,address:$address}"
+					mode: SINGLE,
+					secretHeaders: ["GITHUB-API-TOKEN"]
+				}
+			)
+		age: Int! @search
+  	}
+
+# Dgraph.Secret GITHUB-API-TOKEN "some-api-token"
+  `
+
+	updateSchemaRequireNoGQLErrors(t, schema)
+	time.Sleep(2 * time.Second)
+
+	users := addUsers(t)
+
+	queryUser := `
+	query ($id: [ID!]){
+		queryUser(filter: {id: $id}, order: {asc: age}) {
+			name
+			age
+		}
+	}`
+	params := &common.GraphQLParams{
+		Query: queryUser,
+		Variables: map[string]interface{}{"id": []interface{}{
+			users[0].ID, users[1].ID, users[2].ID}},
+	}
+
+	result := params.ExecuteAsPost(t, alphaURL)
+	require.Nilf(t, result.Errors, "%+v", result.Errors)
+}
+
 func TestCustomFieldsShouldBeResolved(t *testing.T) {
 	// This test adds data, modifies the schema multiple times and fetches the data.
 	// It has the following modes.

graphql/resolve/resolver.go

@@ -1793,6 +1793,7 @@ func (hr *httpResolver) rewriteAndExecute(ctx context.Context, field schema.Fiel
 		}
 		body = string(b)
 	}
+
 	b, err := makeRequest(hr.Client, hrc.Method, hrc.URL, body, hrc.ForwardHeaders)
 	if err != nil {
 		return emptyResult(externalRequestError(err, field))

graphql/schema/wrappers.go

@@ -1841,22 +1841,18 @@ func parseBodyTemplate(body string) (*interface{}, map[string]bool, error) {
 	return &m, requiredFields, nil
 }
 
-func getVar(key string, variables map[string]interface{}) (interface{}, error) {
+func getVar(key string, variables map[string]interface{}) (interface{}, error, bool) {
 	if !strings.HasPrefix(key, "$") {
-		return nil, errors.Errorf("expected a variable to start with $. Found: %s", key)
+		return nil, errors.Errorf("expected a variable to start with $. Found: %s", key), true
 	}
 	val, ok := variables[key[1:]]
-	if !ok {
-		return nil, errors.Errorf("couldn't find variable: %s in variables map", key)
-	}
-
-	return val, nil
+	return val, nil, ok
 }
 
 func substituteSingleVarInBody(key string, valPtr *interface{},
 	variables map[string]interface{}) error {
 	// Look it up in the map and replace.
-	val, err := getVar(key, variables)
+	val, err, _ := getVar(key, variables)
 	if err != nil {
 		return err
 	}
@@ -1868,11 +1864,15 @@ func substituteVarInMapInBody(object, variables map[string]interface{}) error {
 	for k, v := range object {
 		switch val := v.(type) {
 		case string:
-			vval, err := getVar(val, variables)
+			vval, err, ok := getVar(val, variables)
 			if err != nil {
 				return err
 			}
-			object[k] = vval
+			if ok {
+				object[k] = vval
+			} else {
+				delete(object, k)
+			}
 		case map[string]interface{}:
 			if err := substituteVarInMapInBody(val, variables); err != nil {
 				return err
@@ -1892,10 +1892,15 @@ func substituteVarInSliceInBody(slice []interface{}, variables map[string]interf
 	for k, v := range slice {
 		switch val := v.(type) {
 		case string:
-			vval, err := getVar(val, variables)
+			vval, err, _ := getVar(val, variables)
 			if err != nil {
 				return err
 			}
+			//if ok {
+			//	slice[k] = vval
+			//} else {
+			//	delete(object, k)
+			//}
 			slice[k] = vval
 		case map[string]interface{}:
 			if err := substituteVarInMapInBody(val, variables); err != nil {

graphql/schema/wrappers_test.go

@@ -424,11 +424,18 @@ func TestSubstituteVarsInBody(t *testing.T) {
 			nil,
 		},
 		{
-			"variable not found error",
+			"Skip one missing variable in the HTTP body",
 			map[string]interface{}{"postID": "0x9"},
 			map[string]interface{}{"author": "$id", "post": map[string]interface{}{"id": "$postID"}},
+			map[string]interface{}{"post": map[string]interface{}{"id": "0x9"}},
+			nil,
+		},
+		{
+			"Skip all missing variables in the HTTP body",
+			map[string]interface{}{},
+			map[string]interface{}{"author": "$id", "post": map[string]interface{}{"id": "$postID"}},
+			map[string]interface{}{"post": map[string]interface{}{}},
 			nil,
-			errors.New("couldn't find variable: $id in variables map"),
 		},
 	}