Stop always cascading associations for inserts

grails-datastore-gorm-mongodb/src/main/groovy/org/grails/datastore/mapping/mongo/engine/MongoCodecEntityPersister.groovy

@@ -313,7 +313,7 @@ class MongoCodecEntityPersister extends ThirdPartyCacheEntityPersister<Object> {
                         if (proxyFactory.isInitialized(value)) {
                             def dirtyCheckable = (DirtyCheckable) value
                             if (dirtyCheckable.hasChanged()) {
-                                if (!isUpdate || association.isOwningSide() || association.doesCascade(CascadeType.PERSIST)) {
+                                if (association.isOwningSide() || association.doesCascade(CascadeType.PERSIST)) {
                                     mongoCodecSession.persist(value)
                                 }
                             }

grails-datastore-gorm-mongodb/src/test/groovy/grails/mongodb/cascade/MongoCascadeSpec.groovy

@@ -0,0 +1,50 @@
+package grails.mongodb.cascade
+
+import grails.gorm.tests.GormDatastoreSpec
+
+class MongoCascadeSpec extends GormDatastoreSpec {
+
+    @Override
+    List getDomainClasses() {
+        [Product, ProductLine]
+    }
+
+    void "test association is not cascaded on update or insert"() {
+        given:
+        ProductLine x = new ProductLine(name: "x")
+        x.save()
+        session.flush()
+        session.clear()
+
+        Product product = new Product(name: "my product", productLine: ProductLine.load(x.id))
+        product.save()
+        session.flush()
+        session.clear()
+
+        when:
+        product = Product.get(product.id)
+
+        then:
+        product.productLine.name == "x"
+
+        when: //no cascading on update
+        product.productLine.name = "xy"
+        product.save()
+        session.flush()
+        session.clear()
+        x = ProductLine.get(x.id)
+
+        then:
+        x.name == "x"
+
+        when:
+        x.name = "xy"
+        product = new Product(name: "other product", productLine: x)
+        product.save()
+        session.flush()
+        session.clear()
+
+        then:
+        ProductLine.get(x.id).name == "x"
+    }
+}

grails-datastore-gorm-mongodb/src/test/groovy/grails/mongodb/cascade/Product.groovy

@@ -0,0 +1,15 @@
+package grails.mongodb.cascade
+
+import grails.persistence.Entity
+
+
+@Entity
+class Product {
+
+    String name
+    ProductLine productLine
+
+    static mapping = {
+        productLine(cascade: "none")
+    }
+}

grails-datastore-gorm-mongodb/src/test/groovy/grails/mongodb/cascade/ProductLine.groovy

@@ -0,0 +1,10 @@
+package grails.mongodb.cascade
+
+import grails.persistence.Entity
+
+@Entity
+class ProductLine {
+
+    String name
+
+}