fixed virtual field update issues (GoogleCloudPlatform#7318)

* fixed virtual field upadte issues

* update funcs

---------

Co-authored-by: Edward Sun <sunedward@google.com>

mmv1/products/spanner/terraform.yaml

@@ -139,6 +139,7 @@ overrides: !ruby/object:Overrides::ResourceOverrides
       post_create: templates/terraform/post_create/sleep.go.erb
       pre_delete: 'templates/terraform/pre_delete/spanner_instance.go.erb'
       constants: 'templates/terraform/constants/spanner_instance.go.erb'
+      pre_update: 'templates/terraform/pre_update/spanner_instance.go.erb'
 # This is for copying files over
 files: !ruby/object:Provider::Config::Files
   # These files have templating (ERB) code that will be run.

mmv1/templates/terraform/constants/spanner_database.go.erb

@@ -80,4 +80,20 @@ func validateDatabaseRetentionPeriod(v interface{}, k string) (ws []string, erro
 	}
 
 	return
+}
+
+func resourceSpannerDBVirtualUpdate(d *schema.ResourceData, resourceSchema map[string]*schema.Schema) bool {
+	// deletion_protection is the only virtual field
+	if d.HasChange("deletion_protection") {
+		for field := range resourceSchema {
+			if field == "deletion_protection" {
+				continue
+			}
+			if d.HasChange(field) {
+				return false
+			}
+		}
+		return true
+	}
+	return false
 }

mmv1/templates/terraform/constants/spanner_instance.go.erb

@@ -45,4 +45,20 @@ func deleteSpannerBackups(d *schema.ResourceData, config *Config, res map[string
 		}
 	}
 	return nil
-}
+}
+
+func resourceSpannerInstanceVirtualUpdate(d *schema.ResourceData, resourceSchema map[string]*schema.Schema) bool {
+	// force_destroy is the only virtual field
+	if d.HasChange("force_destroy") {
+		for field := range resourceSchema {
+			if field == "force_destroy" {
+				continue
+			}
+			if d.HasChange(field) {
+				return false
+			}
+		}
+		return true
+	}
+	return false
+}

mmv1/templates/terraform/pre_update/spanner_database.go.erb

@@ -17,4 +17,13 @@ if len(obj["statements"].([]string)) == 0 {
 	// Return early to avoid making an API call that errors,
 	// due to containing no DDL SQL statements
 	return resourceSpannerDatabaseRead(d, meta)
+}
+
+if resourceSpannerDBVirtualUpdate(d, resourceSpannerInstance().Schema) {
+    if d.Get("deletion_protection") != nil {
+        if err := d.Set("deletion_protection", d.Get("deletion_protection")); err != nil {
+            return fmt.Errorf("Error reading Instance: %s", err)
+        }
+    }
+    return nil
 }

mmv1/templates/terraform/pre_update/spanner_instance.go.erb

@@ -0,0 +1,8 @@
+if resourceSpannerInstanceVirtualUpdate(d, resourceSpannerInstance().Schema) {
+    if d.Get("force_destroy") != nil {
+        if err := d.Set("force_destroy", d.Get("force_destroy")); err != nil {
+            return fmt.Errorf("Error reading Instance: %s", err)
+        }
+    }
+    return nil
+}