CODEWITHSUNDEEP
wpfvalidationidataerrorinfo
Ravi
Ravi

Reputation: 11

How to Clear WPF IDataErrorInfo Validation Errors

I am using IDataErrorInfo inherited business objects for validation.

public string UserId { get; set; }

public string this[string columnName]
    {
        get
        {
            string result = null;

            if (columnName == "UserId")
            {
                if (string.IsNullOrEmpty(UserId))
                    result = "Please enter User Id";
            }
        }
    }

I want to clear all the validation errors when I click a button on the menu - like - LogOut.

Window is making the Login panel visible but the previous panel's validation error marks are still appearing in the current login panel.

I tried all the options to assign NULL datacontext, fresh entity object...but no luck

I appreciate your help.

Upvotes: 1

Views: 1757

Answers (1)

Sheridan
Sheridan

Reputation: 69959

Using the IDataErrorInfo interface is an error-first type approach. This means that you will see the error(s) until they are cleared. You can see that there is no setter on the indexer.

The original IDataErrorInfo interface is not overly useful by itself as it only deals with one error at a time. I added the following field into my BaseDataType class:

protected ObservableCollection<string> errors = new ObservableCollection<string>();

In my actual data classes, I have the following property:

public override ObservableCollection<string> Errors
{
    get
    {
        errors = new ObservableCollection<string>();
        errors.AddUniqueIfNotEmpty(this["Property1"]);
        errors.AddUniqueIfNotEmpty(this["Property2"]);
        errors.AddUniqueIfNotEmpty(this["PropertyN"]);
        return errors;
    }
}

The AddUniqueIfNotEmpty method is an extension method which I believe is self-explanatory. This property calls the indexer any number of times and compiles all of the results into a ObservableCollection<string> collection ready to be displayed in the UI. You'll need to call the INotifyPropertyChanged.PropertyChanged event with the name Errors when Property1, Property2 and PropertyN are updated to make this work.

You could do something like this, but add a setter for you to pass in an empty collection or string when you want to clear the errors.

Upvotes: 2

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