Ensure other field is returned from GetRelation

If the relationship references the same (host) collection, the function would in some circumstances return the known field.  In collection.save, when updating via a secondary one-one field this leads to an infinite loop.

client/descriptions.go

@@ -53,12 +53,14 @@ func (col CollectionDescription) GetFieldByID(id FieldID) (FieldDescription, boo
 }
 
 // GetRelation returns the field that supports the relation of the given name.
-func (col CollectionDescription) GetRelation(name string) (FieldDescription, bool) {
-	if !col.Schema.IsEmpty() {
-		for _, field := range col.Schema.Fields {
-			if field.RelationName == name {
-				return field, true
-			}
+func (col CollectionDescription) GetFieldByRelation(
+	relationName string,
+	otherCollectionName string,
+	otherFieldName string,
+) (FieldDescription, bool) {
+	for _, field := range col.Schema.Fields {
+		if field.RelationName == relationName && !(col.Name == otherCollectionName && otherFieldName == field.Name) {
+			return field, true
 		}
 	}
 	return FieldDescription{}, false

db/collection.go

@@ -1062,7 +1062,7 @@ func (c *collection) save(
 			if isSecondaryRelationID {
 				primaryId := val.Value().(string)
 
-				err = c.patchPrimaryDoc(ctx, txn, relationFieldDescription, primaryKey.DocKey, primaryId)
+				err = c.patchPrimaryDoc(ctx, txn, c.Name(), relationFieldDescription, primaryKey.DocKey, primaryId)
 				if err != nil {
 					return cid.Undef, err
 				}

db/collection_update.go

@@ -350,6 +350,7 @@ func (c *collection) isSecondaryIDField(fieldDesc client.FieldDescription) (clie
 func (c *collection) patchPrimaryDoc(
 	ctx context.Context,
 	txn datastore.Txn,
+	secondaryCollectionName string,
 	relationFieldDescription client.FieldDescription,
 	docKey string,
 	fieldValue string,
@@ -365,7 +366,11 @@ func (c *collection) patchPrimaryDoc(
 	}
 	primaryCol = primaryCol.WithTxn(txn)
 
-	primaryField, ok := primaryCol.Description().GetRelation(relationFieldDescription.RelationName)
+	primaryField, ok := primaryCol.Description().GetFieldByRelation(
+		relationFieldDescription.RelationName,
+		secondaryCollectionName,
+		relationFieldDescription.Name,
+	)
 	if !ok {
 		return client.NewErrFieldNotExist(relationFieldDescription.RelationName)
 	}

planner/type_join.go

@@ -259,7 +259,11 @@ func (p *Planner) makeTypeJoinOne(
 		return nil, err
 	}
 
-	subTypeField, subTypeFieldNameFound := subTypeCollectionDesc.GetRelation(subTypeFieldDesc.RelationName)
+	subTypeField, subTypeFieldNameFound := subTypeCollectionDesc.GetFieldByRelation(
+		subTypeFieldDesc.RelationName,
+		parent.sourceInfo.collectionDescription.Name,
+		subTypeFieldDesc.Name,
+	)
 	if !subTypeFieldNameFound {
 		return nil, client.NewErrFieldNotExist(subTypeFieldDesc.RelationName)
 	}
@@ -481,7 +485,12 @@ func (p *Planner) makeTypeJoinMany(
 		return nil, err
 	}
 
-	rootField, rootNameFound := subTypeCollectionDesc.GetRelation(subTypeFieldDesc.RelationName)
+	rootField, rootNameFound := subTypeCollectionDesc.GetFieldByRelation(
+		subTypeFieldDesc.RelationName,
+		parent.sourceInfo.collectionDescription.Name,
+		subTypeFieldDesc.Name,
+	)
+
 	if !rootNameFound {
 		return nil, client.NewErrFieldNotExist(subTypeFieldDesc.RelationName)
 	}

tests/integration/mutation/update/field_kinds/one_to_one/with_self_ref_test.go

@@ -103,8 +103,6 @@ func TestMutationUpdateOneToOne_SelfReferencingFromPrimary(t *testing.T) {
 	testUtils.ExecuteTestCase(t, test)
 }
 
-/*
-This test will enter an infinite loop
 func TestMutationUpdateOneToOne_SelfReferencingFromSecondary(t *testing.T) {
 	user1ID := "bae-decf6467-4c7c-50d7-b09d-0a7097ef6bad"
 
@@ -191,4 +189,3 @@ func TestMutationUpdateOneToOne_SelfReferencingFromSecondary(t *testing.T) {
 
 	testUtils.ExecuteTestCase(t, test)
 }
-*/