Retrieve errors from the form and bind to a button

[Davide]

Hello,

I'm using SfDataForm with MVVM pattern and  with a custom class bound as source.

I'm using also it with validationmode.lostfocus.

I'd like to bind the IsEnabled property of a button to the errors count of the sfdataform (no errors means the button is enabled), but I do not understand how to get errors dinamically from the object in my viewmodel.

How can I achieve this?

Thanks,

Davide

[Subburaj Pandian Veluchamy]

Hi Davide, 

  

Thank you for contacting Syncfusion support. 

  

We have analyzed your requirement of “Get validation error count in DataForm”.Validation error count can get from ValidationCompletedEvent if you are using DataFormExplicitValidation. Since you are using LostFocus ValidationMode, your requirement can be achieved using DataForm Validated event. ValidatedEvent will be triggered after each DataFormItem validated, in which you can check for whether all fields are valid usingIsValid property of DataFormItem class. 

  

Code Snippet: 

        

private void DataForm_Validated(object sender, ValidatedEventArgs e) 

{ 

          button.IsEnabled = (sender as SfDataForm).ItemManager.DataFormItems.TrueForAll(x => (x asDataFormItem).IsValid); 

  } 

  

We have prepared a simple sample for the same, 

 

Sample link: DataForm 

  

We hope this helps. Kindly revert us if you have any concern. 

 

Regards,
Subburaj Pandian V   

[Davide D Angelo]

Thank you Subburaj,

your answer has solved the issue, but after implemented it, I decided to change the validation mode to "Explicit".

I'd like to validate the form (sfdataform) in my viewmodel, when a button with command has been clicked: how can I achieve this? I'd like to avoid to call validate method of sfdataform in my page.xaml.cs page.

Also, as second question, is there any option to validate the entries in the form in the lost focus and also call the validation mode Explicit?

Regards,

Davide

[Ganeshamoorthy Chandramoorthy]

Hi Davide, 

 

Thanks for the update.

 

Currently we are analyzing on your query, we will analyze and update you the further details in two business days (August 21, 2019). We appreciate your patience until then.  

 

Regards,
Ganeshamoorthy C 

[Subburaj Pandian Veluchamy]

Hi Davide, 

  

Thank you for your patience. 

  

Query 1: Regarding validation using Button command in ViewModel 

DataForm can be validated in ViewModel using Button Command. While button has clicked pass DataForm instance as Command parameter and validate the DataForm in ViewModel using DataForm Validate method. 

  

[Code Snippet] 

[XAML] 

<dataForm:SfDataForm x:Name="dataForm" DataObject="{Binding LoginInfo}" Grid.Row="0"ValidationMode="LostFocus" CommitMode="LostFocus"/> 

  

<Button x:Name="validateButton" Grid.Row="1"  Text="Submit" 

    Command="{Binding Path=BindingContext.ValidateCommand, Source={x:Reference Name=dataForm}}" CommandParameter="{Binding Source={x:Reference Name=dataForm}}"/> 

  

[C#]        

public DataFormViewModel() 

{ 

     loginInfo = new DataFormModel(); 

     this.ValidateCommand = new Command<object>(this.OnValidate); 

} 

  

public Command<object> ValidateCommand { get; set; } 

  

private void OnValidate(object dataForm) 

{ 

       var dataFormLayout = dataForm as Syncfusion.XForms.DataForm.SfDataForm; 

       dataFormLayout.Validate(); 

  } 

  

Query 2: Regarding validating DataFormItems in both LostFocus and Explicit validation 

DataFormItems can be validated explicitly even if ValidationMode set to LostFocus or PropertyChanged but If ValidationMode set to Explicit, then explicit validation only can be done. So, set ValidationMode to LostFocus and call explicit validation using Validate() method both will work fine with DataForm. 

  

We have prepared a simple sample including solutions for both queries,         

 

Sample link: DataForm 

  

We hope this helps. Kindly revert us if you have any concern. 

  

Regards,
Subburaj Pandian V  

[Davide D Angelo]

Hi Subburaj,

that was what I needed.

It works

Thank you,

Davide 

[Subburaj Pandian Veluchamy]

Hi Davide,  

   

Thank you for the update. We are glad that the given solution meets your requirement.

Please get in touch with us, if you would require any further assistance.

 

Regards,
Subburaj Pandian V  

[Mihai Alexandru Dumitru]

Hello, how can we enable or disable the validateButton based on a boolean property on the view model?
Basically we need to somehow update the bool property on the view model with the form.Validate() result.

[Vidyalakshmi Mani]

Hi Mihai,

  

We have reviewed your query, but we are unsure whether you are using SfDataForm in Xamarin.Forms or .NET MAUI. Could you please confirm? This will allow us to provide the most accurate assistance.

Regards,

Vidyalakshmi M.