fix(GraphQL): Fix getType queries when id was used as a name for type…

…s other than ID (#6130)

For the schema

type Tweets {
	id: String! @id
	score: Int
}

getTweets query was not being properly re-written. This is because we were using the name id to signify that a field is of type ID instead of the type ID itself. That has been fixed now. So getTweets would work if the field was named anything.

query MyQuery {
  getTweets(id: "1286891968727982081") {
    score
    id
  }
}

(cherry picked from commit bb8e4b9)

graphql/resolve/query_test.yaml

@@ -1326,7 +1326,7 @@
         }
       }
     }
-  dgquery: |
+  dgquery: |-
     query {
       getPost(func: uid(0x1)) @filter(type(Post)) {
         postID : uid
@@ -1338,4 +1338,20 @@
           url : Comment.url
         }
       }
-    }
+    }
+- name: "getType by id should work"
+  gqlquery: |-
+    query {
+      getTweets(id: "1286891968727982081") {
+        score
+        id
+      }
+    }
+  dgquery: |-
+    query {
+      getTweets(func: eq(Tweets.id, "1286891968727982081")) @filter(type(Tweets)) {
+        score : Tweets.score
+        id : Tweets.id
+        dgraph.uid : uid
+      }
+    }

graphql/resolve/schema.graphql

@@ -239,3 +239,8 @@ type Y implements X @auth(
 ){
   userRole: String @search(by: [hash])
 }
+
+type Tweets {
+    id: String! @id
+    score: Int
+}

graphql/schema/wrappers.go

@@ -87,7 +87,6 @@ const (
 	HTTPMutation         MutationType = "http"
 	NotSupportedMutation MutationType = "notsupported"
 	IDType                            = "ID"
-	IDArgName                         = "id"
 	InputArgName                      = "input"
 	FilterArgName                     = "filter"
 )
@@ -731,8 +730,17 @@ func (f *field) HasCustomDirective() (bool, map[string]bool) {
 func (f *field) XIDArg() string {
 	xidArgName := ""
 	passwordField := f.Type().PasswordField()
-	for _, arg := range f.field.Arguments {
-		if arg.Name != IDArgName && (passwordField == nil ||
+
+	args := f.field.Definition.Arguments
+	if len(f.field.Definition.Arguments) == 0 {
+		// For acl endpoints like getCurrentUser which redirects to getUser resolver, the field
+		// definition doesn't change and hence we can't find the arguments for getUser. As a
+		// fallback, we get the args from the query field arguments in that case.
+		args = f.op.inSchema.schema.Query.Fields.ForName(f.Name()).Arguments
+	}
+
+	for _, arg := range args {
+		if arg.Type.Name() != IDType && (passwordField == nil ||
 			arg.Name != passwordField.Name()) {
 			xidArgName = arg.Name
 		}
@@ -1608,7 +1616,7 @@ func (t *astType) Interfaces() []string {
 // satisfy a valid post.
 func (t *astType) EnsureNonNulls(obj map[string]interface{}, exclusion string) error {
 	for _, fld := range t.inSchema.schema.Types[t.Name()].Fields {
-		if fld.Type.NonNull && !isID(fld) && !(fld.Name == exclusion) {
+		if fld.Type.NonNull && !isID(fld) && fld.Name != exclusion {
 			if val, ok := obj[fld.Name]; !ok || val == nil {
 				return errors.Errorf(
 					"type %s requires a value for field %s, but no value present",