Csla.Blazor.ViewModel and firing specific rules on Save rather than OnModelChanging

[adrianwright109]

Hi,

I am using the Csla.Blazor.ViewModel (aka vm) for my ClientEdit object on a razor page.

I'm subscribing to the ModelPropertyChanged event on the Csla.Blazor.ViewModel to call StateHasChanged() this is allowing the BusinessRules on the ClientEdit object to fire and update the changed Property validation warnings, which in turn only enables the Save button when all fields are valid based on the vm.Model.IsSavable Property.

This is all working great.

The issue I'm facing is that one of the BusinessRules I've added to the ClientName Property isn't very lightweight as its making a database call to determine if the ClientName value already exists in the database as they are required to be unique within the application.

This wouldn't be an issue except for the fact that this BusinessRule like the other BusinessRules are being triggered on every character change (for a textbox).

Is it possible to exclude certain rules so that they only get checked when the ClientEdit object is saved not on the ModelPropertyChanged event?

[rockfordlhotka]

@jonnybee can probably offer the most in-depth answer.

I assume you know about rule priorities, so this long-running rule only runs if the cheaper rules all succeed?

Normally what I'd do, like in WPF or something, is have this particular UI control only update the business object property when the user tabs out, not on keypress. You can do that with Blazor also. This usually solves the issue and is probably the easiest answer.

I know that @jonnybee added some more advanced capabilities to the rules engine, where the context includes info about why the rule is being executed. I don't recall if that allows you do tell the difference between the rule executing due to a property change vs a CheckRules call.

And that's what you are really talking about here. You'd need to override SaveAsync and call CheckRules to trigger the rules to run on save, and have your long-running rule be aware that it should not run normally, but should only run when CheckRules is invoked.

[richardbartley]

There were some RunMode options to control when the rule might fire.

BusinessRules.AddRule(new NotOptionDependencyRulesBroken { PrimaryProperty = SelectedOptionsProperty,
                                                        AffectedProperties = { BrokenOptionDependencyRulesProperty, RevisedSelectedOptionsProperty }, 
                                                                        RunMode = Csla.Rules.RunModes.DenyAsAffectedProperty,
                                                                        Priority = 10 });

Alternatively, in the past I have suspended the rule by using another property to control the rule logic, and then enable it again in the Save method by un-suspending the rule and calling CheckRules manually if needed.