fix(GraphQL): Dgraph directive with reverse edge should work smoothly…

… with interfaces (#5911)

Fixes #5744

There was another bug where field which map to reverse edges in Dgraph where generated as part of AddTypeInput and TypeRef. They have been excluded now as we can't perform a mutation along them. They would earlier have given an error at runtime while doing mutations in Dgraph about predicate being incorrect because it starts with ~. Apart, from that to fix #5744, we also allow interfaces implemented by the current type in the che

graphql/schema/gqlschema.go

@@ -1308,6 +1308,13 @@ func getFieldsWithoutIDType(schema *ast.Schema, defn *ast.Definition) ast.FieldL
 			continue
 		}
 
+		// Remove edges which have a reverse predicate as they should only be updated through their
+		// forward edge.
+		fname := fieldName(fld, defn.Name)
+		if strings.HasPrefix(fname, "~") || strings.HasPrefix(fname, "<~") {
+			continue
+		}
+
 		// see also comment in getNonIDFields
 		if schema.Types[fld.Type.Name()].Kind == ast.Interface &&
 			(!hasID(schema.Types[fld.Type.Name()]) && !hasXID(schema.Types[fld.Type.Name()])) {

graphql/schema/gqlschema_test.yml

@@ -656,6 +656,56 @@ invalid_schemas:
       "locations":[{"line":5, "column":12}]}
     ]
 
+  -
+    name: "Dgraph directive with reverse pred argument matching with wrong type implementing an interface produces an error"
+    input: |
+      type Z {
+        f1: String!
+      }
+      type X {
+        f1: [Z] @dgraph(pred: "f1")
+      }
+
+      interface Person {
+        id: ID!
+      }
+
+      type Y implements Person {
+        f1: [X] @dgraph(pred: "~f1")
+      }
+    errlist: [
+      {"message": "Type X; Field f1: should be any of types Y or Person to be compatible with @dgraph reverse
+      directive but is of type Z.",
+      "locations":[{"line":5, "column":12}]}
+    ]
+
+  -
+    name: "Dgraph directive with reverse pred argument matching with wrong type implementing multiple interfaces produces an error"
+    input: |
+      type Z {
+        f1: String!
+      }
+      type X {
+        f1: [Z] @dgraph(pred: "f1")
+      }
+
+      interface Person {
+        id: ID!
+      }
+
+      interface Student {
+        ids: String! @id
+      }
+
+      type Y implements Person & Student {
+        f1: [X] @dgraph(pred: "~f1")
+      }
+    errlist: [
+      {"message": "Type X; Field f1: should be any of types Y, Person or Student to be compatible with @dgraph reverse
+      directive but is of type Z.",
+      "locations":[{"line":5, "column":12}]}
+    ]
+
   -
     name: "Field with a dgraph directive with reverse pred argument should be a list"
     input: |
@@ -2451,9 +2501,13 @@ valid_schemas:
     name: "dgraph directive with correct reverse field works"
     input: |
       type X {
+        id: ID!
+        name: String
         f1: [Y] @dgraph(pred: "~f1")
       }
       type Y {
+        id: ID!
+        name: String
         f1: [X] @dgraph(pred: "f1")
       }
 
@@ -2605,3 +2659,22 @@ valid_schemas:
           body: "{sid: $id}"
           })
       }
+
+  -
+    name: "dgraph directive with reverse edges should work with interfaces"
+    input: |
+      type Object {
+        id: ID!
+        name: String
+        ownedBy: Person @dgraph(pred: "Object.owner")
+      }
+
+      type BusinessMan implements Person {
+        companyName: String
+      }
+
+      interface Person {
+        id: ID!
+        name: String
+        owns: [Object] @dgraph(pred: "~Object.owner")
+      }

graphql/schema/introspection_test.go

@@ -1,7 +1,6 @@
 package schema
 
 import (
-	"fmt"
 	"io/ioutil"
 	"path/filepath"
 	"testing"
@@ -366,7 +365,6 @@ func TestFullIntrospectionQuery(t *testing.T) {
 
 	queries := oper.Queries()
 	resp, err := Introspect(queries[0])
-	fmt.Println(string(resp))
 	require.NoError(t, err)
 
 	expectedBuf, err := ioutil.ReadFile("testdata/introspection/output/full_query.json")

graphql/schema/rules.go

@@ -1085,12 +1085,30 @@ func dgraphDirectiveValidation(sch *ast.Schema, typ *ast.Definition, field *ast.
 				continue
 			}
 			if predArg.Value.Raw == forwardEdgePred {
-				if fld.Type.Name() != typ.Name {
-					errs = append(errs, gqlerror.ErrorPosf(dir.Position, "Type %s; Field %s: should be of"+
-						" type %s to be compatible with @dgraph reverse directive but is of"+
-						" type %s.", invTypeName, fld.Name, typ.Name, fld.Type.Name()))
+				possibleTypes := append([]string{typ.Name}, typ.Interfaces...)
+				allowedType := false
+				for _, pt := range possibleTypes {
+					if fld.Type.Name() == pt {
+						allowedType = true
+						break
+					}
+				}
+				if !allowedType {
+					typeMsg := ""
+					if len(possibleTypes) == 1 {
+						typeMsg = fmt.Sprintf("of type %s", possibleTypes[0])
+					} else {
+						l := len(possibleTypes)
+						typeMsg = fmt.Sprintf("any of types %s or %s",
+							strings.Join(possibleTypes[:l-1], ", "), possibleTypes[l-1])
+					}
+					errs = append(errs, gqlerror.ErrorPosf(dir.Position, "Type %s; Field %s: "+
+						"should be %s to be compatible with @dgraph"+
+						" reverse directive but is of type %s.",
+						invTypeName, fld.Name, typeMsg, fld.Type.Name()))
 					return errs
 				}
+
 				invDirective := fld.Directives.ForName(inverseDirective)
 				if invDirective != nil {
 					errs = append(errs, gqlerror.ErrorPosf(
@@ -1183,7 +1201,7 @@ func customDirectiveValidation(sch *ast.Schema,
 	if httpArg.Value.Kind != ast.ObjectValue {
 		errs = append(errs, gqlerror.ErrorPosf(
 			httpArg.Position,
-			"Type %s; Field %s: http argument for @custom directive should be of type Object.",
+			"Type %s; Field %s: http argument for @custom directive ff type Object.",
 			typ.Name, field.Name))
 	}
 

graphql/schema/testdata/schemagen/input/interface-with-dgraph-pred.graphql

@@ -0,0 +1,15 @@
+type Object {
+  id: ID!
+  name: String
+  ownedBy: Person @dgraph(pred: "Object.owner")
+}
+
+type BusinessMan implements Person {
+  companyName: String
+}
+
+interface Person {
+  id: ID!
+  name: String
+  owns: [Object] @dgraph(pred: "~Object.owner")
+}

graphql/schema/testdata/schemagen/output/dgraph-reverse-directive-on-concrete-type-with-interfaces.graphql

@@ -210,7 +210,6 @@ enum OscarMovieOrderable {
 
 input AddDirectorInput {
 	name: String!
-	directed: [OscarMovieRef]
 }
 
 input AddOscarMovieInput {
@@ -237,7 +236,6 @@ input DirectorPatch {
 input DirectorRef {
 	id: ID
 	name: String
-	directed: [OscarMovieRef]
 }
 
 input MovieFilter {

graphql/schema/testdata/schemagen/output/dgraph-reverse-directive-with-interfaces.graphql

@@ -215,7 +215,6 @@ input AddDirectorInput {
 
 input AddOscarMovieInput {
 	name: String!
-	director: [DirectorRef]
 	year: Int!
 }
 
@@ -279,7 +278,6 @@ input OscarMoviePatch {
 input OscarMovieRef {
 	id: ID
 	name: String
-	director: [DirectorRef]
 	year: Int
 }
 

graphql/schema/testdata/schemagen/output/field-with-reverse-predicate-in-dgraph-directive.graphql

@@ -192,7 +192,6 @@ input AddMovieDirectorInput {
 
 input AddMovieInput {
 	name: String!
-	director: [MovieDirectorRef]
 }
 
 input MovieDirectorFilter {
@@ -235,7 +234,6 @@ input MoviePatch {
 input MovieRef {
 	id: ID
 	name: String
-	director: [MovieDirectorRef]
 }
 
 input UpdateMovieDirectorInput {