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When will the custom description be used?

Printed From: IdeaBlade
Category: DevForce
Forum Name: DevForce 2009
Forum Discription: For .NET 3.5
URL: http://www.ideablade.com/forum/forum_posts.asp?TID=1509
Printed Date: 21-Sep-2025 at 9:28pm


Topic: When will the custom description be used?
Posted By: LesleySastro
Subject: When will the custom description be used?
Date Posted: 05-Oct-2009 at 8:11am
I have the following custom verifier (see below). The idea is that the IdentificationNumberEntityProperty is required under certain conditions. The custom description I wrote is never used. Any ideas why? 

#region Identification Number

private class IdentificationNumberRequiredVerifier : PropertyValueVerifier<AccountMutation>

{

public IdentificationNumberRequiredVerifier()

: base ( new PropertyValueVerifierArgs<AccountMutation>(

IdentificationNumberEntityProperty.Name, true, "Identification Number"))

{

ExecutionModes = VerifierExecutionModes.InstanceAndOnPostsetTriggers;

}

protected override VerifierResult VerifyValue(object itemToVerify, object valueToVerify,

TriggerContext triggerContext, VerifierContext verifierContext)

{

if ((itemToVerify is AccountMutation) && (

(((AccountMutation)itemToVerify).Action == 1) || // New Account

(((AccountMutation)itemToVerify).Action == 2) || // Change Personal Info

(((AccountMutation)itemToVerify).Action == 5) || // Change All Info

(((AccountMutation)itemToVerify).Action == 7))) // Reactivate Account

{

if ((valueToVerify == null) || (string.IsNullOrEmpty(valueToVerify.ToString().Trim())))

return new VerifierResult(false, Description);

}

return new VerifierResult(true);

}

protected override VerifierResult VerifyValueTyped(AccountMutation itemToVerify, object valueToVerify,

TriggerContext triggerContext, VerifierContext verifierContext)

{

return VerifyValue(itemToVerify, valueToVerify, triggerContext, verifierContext);

}

public override string Description

{

get

{

// TODO Localize

return "Identification Number is required. ***";

}

}

}

#endregion


Replies:
Posted By: GregD
Date Posted: 06-Oct-2009 at 7:09pm
I took your code and tweaked it into a Country verifier for the Customer entity of NorthwindIB. Any subsequent attempt to set the Country property to null (regardless of the value of the Action property) elicited a generic "Country is required" message (not your custom message).

So I set a break point inside your VerifyValue() method and found that it never runs. The null check is simply resulting from the true setting on the second parameter of your call to the PropertyValueVerifierArgs constructor):


public IdentificationNumberRequiredVerifier()

: base ( new PropertyValueVerifierArgs<AccountMutation>(

IdentificationNumberEntityProperty.Name, true, "Identification Number"))

Posted By: LesleySastro
Date Posted: 07-Oct-2009 at 8:54am
Thanks Greg, I suspected that already. Setting the parameter to false will not help either, because the verifier will not run when the property is null, only when a value is entered for that property. So the big question is how to create a custom required verifier (one that will display my custom error message). For example, in your test when the country is USA the state should be a required property.

Posted By: GregD
Date Posted: 07-Oct-2009 at 6:50pm
You can do just about anything with a delegate verifier. Here's one that makes the Title for an Employee required if the provided FirstName is less than two characters long.  (I modified the delegate verifier example from the Code Samples in the Validation topic.)

    #region Conditional Required Verifier

    private static Verifier TitleRequiredIfFirstNameIsShort() {
      string description = "A Title is required if the first name is shorter than two characters.";
      DelegateVerifier<Employee> v =
        new DelegateVerifier<Employee>(description, TitleRequiredCondition);
      v.AddTrigger(Employee.TitleEntityProperty.Name);
      v.ExecutionModes = VerifierExecutionModes.InstanceAndOnPostsetTriggers;
      return v;
    }

    private static VerifierResult TitleRequiredCondition(
      Employee pEmp, TriggerContext pTriggerContext,
      VerifierContext pVerifierContext) {

      if (pTriggerContext != null &&
        // We are not checking the proposed value because don't expect to call it preset
        pTriggerContext.Timing == TriggerTiming.Preset) {
        throw new VerifierException("TitleRequired verifier not implemented for Preset");
      }
      bool isValid = true;
      if (pEmp.FirstName.Length < 2 && pEmp.Title == null) {
        isValid = false;
      }
      return new VerifierResult(isValid);
    }

    #endregion


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