CODEWITHSUNDEEP
c#wpfmvvmdata-binding
Chan
Chan

Reputation: 15

WPF Databinding from custom property not updating

I'm new to WPF Data binding and can't figure it how to update the property from my viewmodel

I have a class named Patient

public string FirstName { get; set; } = "";
public string MiddleName { get; set; } = "";
public string LastName { get; set; } = "";

updates to the patient class is working

private Data.Patient patient;
public Data.Patient Patient
{
     get { return patient; }
     set
     {
          patient = value;
          NotifyPropertyChanged("Patient");
     }
}

a property on my viewmodel which is not updated by the patient class

public string FullName
{
     get { return Patient.LastName + " " + Patient.FirstName + " " + Patient.MiddleName; }
}

I'm trying to update the TextBlock Text property

 <TextBlock Text="{Binding FullName}" FontSize="14.667" />

how to apply the updates from the Class to my FullName property? Updates are applied when I rerun the application.

Many Thanks

Upvotes: 1

Views: 631

Answers (4)

Shaharyar
Shaharyar

Reputation: 12449

Your problem is you're not notifying UI that Fullname property has changed. Technically it has not changed, but it is dependent on some other property.

The simplest solution here is to raise NotifyProperty event for all properties. You won't have to write plenty of code for it, just pass null in NotifyPropertyChanged();

private Data.Patient patient;

public Data.Patient Patient
{
     get { return patient; }
     set
     {
          patient = value;
          NotifyPropertyChanged(null); //informs view that all properties updated
     }
}

It will tell your model that all properties have been updated.

MSDN:

The PropertyChanged event can indicate all properties on the object have changed by using either null or String.Empty as the property name in the PropertyChangedEventArgs.

Upvotes: 1

Chan
Chan

Reputation: 15

I can't seem to make it work. I added the property to my class so any changes to the class will be notify the UI, still it's not working the way I want. But I found a solution.

<TextBlock FontSize="14.667">
     <TextBlock.Text>
          <MultiBinding StringFormat=" {0} {1} {2}">
               <Binding Path="Patient.LastName" />
               <Binding Path="Patient.FirstName"/>
               <Binding Path="Patient.MiddleName"/>
          </MultiBinding>
     </TextBlock.Text>
</TextBlock>

Thanks for the help.

Upvotes: 0

scher
scher

Reputation: 1923

Like the Patient property with the NotifyPropertyChanged(...), you have to inform the, when the property Fullname has changed. To do that, call NotifyPropertyChanged("FullName") in the setters of the three properties: FirstName, MiddleName and LastName.

Also consider, that NotifyPropertyChanged could be null and use therefore:

if (NotifyPropertyChanged != null)
    NotifyPropertyChanged("FullName");

Upvotes: 0

Felix D.
Felix D.

Reputation: 5133

Change your binding from Text="{Binding FullName}" to Text="{Binding FullName, Mode="OneWay", UpdateSourceTrigger="PropertyChanged"}" that should trigger the PropertyChanged-Event.

Upvotes: 0

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