Fix Changeset with partially updated has many association

changeset.go

@@ -118,6 +118,7 @@ func (c Changeset) applyAssocMany(field string, mut *Mutation) {
 			assoc      = c.doc.Association(field)
 			col, _     = assoc.Collection()
 			muts       = make([]Mutation, 0, col.Len())
+			mutsCount  = 0
 			updatedIDs = make(map[interface{}]struct{})
 			deletedIDs []interface{}
 		)
@@ -130,12 +131,15 @@ func (c Changeset) applyAssocMany(field string, mut *Mutation) {
 
 			if ch, ok := chs[pValue]; ok {
 				updatedIDs[pValue] = struct{}{}
+				mut := Apply(doc, ch)
+				muts = append(muts, mut)
 
-				if amod := Apply(doc, ch); !amod.IsEmpty() {
-					muts = append(muts, amod)
+				if !mut.IsEmpty() {
+					mutsCount++
 				}
 			} else {
 				muts = append(muts, Apply(doc, newStructset(doc, false)))
+				mutsCount++
 			}
 		}
 
@@ -148,7 +152,7 @@ func (c Changeset) applyAssocMany(field string, mut *Mutation) {
 			}
 		}
 
-		if len(muts) > 0 || len(deletedIDs) > 0 {
+		if mutsCount > 0 || len(deletedIDs) > 0 {
 			mut.SetAssoc(field, muts...)
 			mut.SetDeletedIDs(field, deletedIDs)
 		}

changeset_test.go

@@ -503,6 +503,7 @@ func TestChangeset_hasMany(t *testing.T) {
 			Transactions: []Transaction{
 				{ID: 11, Item: "Book", Status: "pending"},
 				{ID: 12, Item: "Eraser", Status: "pending"},
+				{ID: 13, Item: "Pencil", Status: "pending"},
 			},
 		}
 		snapshots = [][]interface{}{
@@ -576,6 +577,10 @@ func TestChangeset_hasMany(t *testing.T) {
 								"address_id": Set("address_id", 0),
 							},
 						},
+						{
+							Cascade: true,
+							Mutates: nil, // nil mutates to satisfy repository saveHasMany check
+						},
 					},
 					DeletedIDs: []interface{}{12},
 				},

repository.go

@@ -375,7 +375,7 @@ func (r repository) insert(cw contextWrapper, doc *Document, mutation Mutation)
 	}
 
 	// update primary value
-	if pField != "" {
+	if pField != "" && !isZero(pValue) {
 		doc.SetValue(pField, pValue)
 	}
 
@@ -740,8 +740,10 @@ func (r repository) saveHasMany(cw contextWrapper, doc *Document, mutation *Muta
 					muts[i], muts[updateCount] = muts[updateCount], muts[i]
 				}
 
-				if err := r.update(cw, assocDoc, muts[updateCount], filter); err != nil {
-					return err
+				if !muts[updateCount].IsEmpty() {
+					if err := r.update(cw, assocDoc, muts[updateCount], filter); err != nil {
+						return err
+					}
 				}
 
 				updateCount++