DataLayoutControl - Databinding Problem with LookupEdit and Complex Object

Brian Kiser

created 10 years ago (modified 9 years ago)

I have a DataLayoutControl on a Winform bound to a bindingsource. The datasource property is set to a custom object below:

C#
public class Complaint : BusinessBase<Complaint>  
{  
    // complex object property  
    public WagePaymentMethod PaymentMethod  
    {  
        get { return GetProperty(paymentMethodProperty); }  
        set { SetProperty(paymentMethodProperty, value); }  
    }

One of my fields on the DataLayoutControl is set to a LookUpEdit which is bound to a different BindingSource and that datasource property on that binding source is set to a list of PaymentMethod objects so that the dropdown shows a list of payment methods (Hourly, Monthly, etc). The dropdown works and shows the description field of each PaymentMethod objects. When I select one (ex: Hourly), it places the text in the box and when I tab off of it, I get an casting error

Unable to cast object of type 'Labor.WageAndHour.BusinessLayer.WagePaymentMethod' to type 'System.String'

I have set the ValueMember property to null thinking that the binding mechanism would try to place the entire object (WagePaymentMethod) from the dropdown into the Complaint.ClaimantWagePaymentMethod property but this is not the case.

I need know how to tell your binding mechanism to assign the entire selected object in the dropdown to the the property which is a complex object so that I don't get a casting error?

DataLayout... Error.png

Answers approved by DevExpress Support

DevExpress Support Team

created 10 years ago

Hi,

If you leave the ValueMember property empty, LookUpEdit's edit value will be a whole underlying object. If the LookUpEdit.EditValue property is bound to the PaymentMethod property while LookUpEdit's data source is a list of WagePaymentMethod objects, everything should work as expected. I have attached a project to illustrate this. Please modify it to show the issue.

I look forward to your response.

T266518.zip

Show previous comments (5)

Brian Kiser 10 years ago

I opened your solution in Visual Studio 2013 and tried to run it and got the following error:
{"Cannot bind to the property or column PaymentMethod on the DataSource.\r\nParameter name: dataMember"}
On this line of code in Main()
Application.Run(new Form1());

Brian Kiser 10 years ago

Nevermind, I deleted the folder, extracted the solution again and now it seems to work. I'll look over it and see if I can duplicate the problem. Thanks.

DevExpress Support Team 10 years ago

Hi,

OK. I look forward to your response.

Brian Kiser 9 years ago

Okay, I was able to get this to work from the stand point of creating a new Complaint object binding it to the DataLayOutControl and having the user select a payment method from the LookUpEdit control and it will indeed place the selected WagePaymentMethod object into the bound Complaint object.
However, here is my next hurdle. I use the same form to edit an existing Complaint object that already has a WagePaymentMethod assigned to its Complaint.WagePaymentMethod property. When the form binds the Complaint to the DataLayoutControl and the LookUpEdit is bound to the complete list of WagePaymentMethods, all the fields load the correct data and display the text except the lookupEdit control which is blank?
How do I get the LookUpEdit control to display the WagePaymentMethod Description property? I have the DisplayMember property of the LookupEdit Data Binding Mode set to "Description" and again it does show the description correctly when the user selects a WagePaymentMethod from the dropdown but it doesn't show when loading an existing Complaint record.
Thanks for any help you can offer.

Sasha (DevExpress Support) 9 years ago

Hello Mark,
It's likely that the issue occurs because a WagePaymentMethod instance stored in the Complaint object doesn't exist in the LookUpEdit's data source. Thus, when the Complaint object is selected, LookUpEdit's EditValue is set to this WagePaymentMethod instance, but this instance is not found in the WagePaymentMethod object collection and the description is not shown.
Would you please clarify how you fill the Complaint and WagePaymentMethod collections so that I can find the most precise solution? Are they stored in the data base?

I am looking forward to your response.

Brian Kiser 9 years ago

You are exactly correct. My Complaint.WagePaymentMethod property was loaded from the database and the list of all possible WagePaymentMethods were retrieved and bound to the LookUpEdit dropdown. The problem was that the control could not find the current WagePaymentMethod in the list because when evaluating whether they were equal, they were not because they were not the same object. All I had to do was override the Equals method and tell it how to determine if the objects were logically equal and then it worked great.
Thanks
Mark

Brian Kiser 9 years ago

Okay I have one more question related to databinding a property that is a complex object and required attributes.
I have the property defined as this…

C#
[Required()]  
public WagePaymentMethod ClaimantWagePaymentMethod  
{  
   get { return GetProperty(wagePaymentMethodProperty); }  
   set  
   {  
       SetProperty(wagePaymentMethodProperty, value);  
   }  
}

However, the dxErrorProvider is not enforcing this required attribute for the LookUpEdit control bound to this. Why? Is there a trick to get that type of scenario to work?

Sasha (DevExpress Support) 9 years ago

Hello Mark,
From what I gather, the initial issue has been resolved. To avoid mixing several questions in one thread, I've created a separate ticket for your question about DxErrorProvider. I will answer you in the DxErrorProvider - How to use it for properties marked with the 'Required' attribute thread.

Created: July 13, 2015 8:44 PM

Modified: October 2, 2015 10:19 AM

Platform: WinForms

Product: XtraLayout Suite

Build: 15.1.4

IDE: Microsoft Visual Studio 2013

Disclaimer: The information provided on DevExpress.com and affiliated web properties (including the DevExpress Support Center) is provided "as is" without warranty of any kind. Developer Express Inc disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. Please refer to the DevExpress.com Website Terms of Use for more information in this regard.

Confidential Information: Developer Express Inc does not wish to receive, will not act to procure, nor will it solicit, confidential or proprietary materials and information from you through the DevExpress Support Center or its web properties. Any and all materials or information divulged during chats, email communications, online discussions, Support Center tickets, or made available to Developer Express Inc in any manner will be deemed NOT to be confidential by Developer Express Inc. Please refer to the DevExpress.com Website Terms of Use for more information in this regard.

DataLayoutControl - Databinding Problem with LookupEdit and Complex Object

Answers approved by DevExpress Support

Recently viewed tickets