Xaml converterparameter

The Enable Buttons page demonstrates a common need when a Button performs an operation based on text that the user types into an Entry view.

If nothing has been typed into the Entry , the Button should be disabled. Each Button contains a data binding on its IsEnabled property. The data-binding source is the Length property of the Text property of the corresponding Entry. If that Length property is not 0, the value converter returns true and the Button is enabled:. Notice that the Text property in each Entry is initialized to an empty string. The Text property is null by default, and the data binding will not work in that case.

Some value converters are written specifically for particular applications, while others are generalized. If you know that a value converter will only be used in OneWay bindings, then the ConvertBack method can simply return null. The Convert method shown above implicitly assumes that the value argument is of type int and the return value must be of type bool. Similarly, the ConvertBack method assumes that the value argument is of type bool and the return value is int.

If that is not the case, a runtime exception will occur. You can write value converters to be more generalized and to accept several different types of data. The Convert and ConvertBack methods can use the as or is operators with the value parameter, or can call GetType on that parameter to determine its type, and then do something appropriate. The expected type of each method's return value is given by the targetType parameter. Sometimes, value converters are used with data bindings of different target types; the value converter can use the targetType argument to perform a conversion for the correct type.

If the conversion being performed is different for different cultures, use the culture parameter for this purpose. The parameter argument to Convert and ConvertBack is discussed later in this article. Value converter classes can have properties and generic parameters. This particular value converter converts a bool from the source to an object of type T for the target:. The Switch Indicators page demonstrates how it can be used to display the value of a Switch view.

Although it's common to instantiate value converters as resources in a resource dictionary, this page demonstrates an alternative: Each value converter is instantiated between Binding. Converter property-element tags. The x:TypeArguments indicates the generic argument, and TrueObject and FalseObject are both set to objects of that type:. In the last of the three Switch and Label pairs, the generic argument is set to Style , and entire Style objects are provided for the values of TrueObject and FalseObject.

These override the implicit style for Label set in the resource dictionary, so the properties in that style are explicitly assigned to the Label.

Toggling the Switch causes the corresponding Label to reflect the change:. Since we haven't heard from you for a long time, I temporarily close this case. If you have any concerns, please free feel to reopen it or submit a new question. We are trying to better understand customer views on social support experience, so your participation in this interview project would be greatly appreciated if you have time.

Thanks for helping make community forums a great place. Click HERE to participate the survey. Ask a question. Quick access. Search related threads. Remove From My Forums. Answered by:. Connect and share knowledge within a single location that is structured and easy to search. I have a binding with converter.

I want to pass the " ,,. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 8 years, 3 months ago. Active 8 years, 3 months ago. Viewed 7k times. How to pass this string correctly? Cristian Lupascu