In WPF, what is the difference between x:Key
and x:Name
? In which cases should one or the other be used?
I know it x:Key
can be set with one markup-extension
like this:
x:Key="{x:Static local:MisKeys.MiKey}"
But x:Name
no. Why is this? I don't like to hardcode strings
and with x:Name
that I am forced to do it.
I would like to know if both properties are "interchangeable" in some context, because I prefer to use x:Key
everything possible since I can set it with a constant.
x.Key
is a property of an item within aResourceDictionary
. It is used to identify a resource within a resource dictionary.Instead
x:Name
it is the identifier in C# that corresponds to the XAML tag to which the is addedx:Name
, this is how you can reference it from C# .With this example I hope everything is clear:
XAML
C#
#FFFFFFFF
In this example, the value that corresponds to the color white is displayed in a MessageBox .As you can see
NameDelGrid
, it is the name of a field that belongs toMainWindow
, it is not a value that can be modified dynamically, but rather it is the name of a property of the class.x:Key
is used to identify objects in a resource dictionary:x:Name
is used to identify user interface elements:You can add a
x:Name
to a resource, but you can't use its value to reference it withStaticResource
. You can't usex:Key
outside of a resource dictionary.Well I have a cold time with XAML (but it used to be very good modesty aside)
Just put the
Name
and mark the access to the texbox aspublic
so that you can access it as a member of the instance from outside of it.Using the
Name
even if you have to always write it asstring
will always be the alternative to follow to access the tree of UI objects within XAML.You are not hardcoding anything
The platform was designed like this. To access an object within the 'DOM' xaml you must navigate through a complex hierarchy of objects and when the UI is rich enough it becomes a matter of guessing which object in the hierarchy you are in .
To avoid this then you can identify the objects by their name, if you have everything very well set up with MVVM you will rarely need it because the binding will take care of solving what is necessary, however you will always find a scenario where the binding alone is not enough to figure it all out (sometimes you're not as good with MVVM as you think, but that's another story). In those cases, you must find the most appropriate way to interact with some of the objects in the hierarchy, and the easiest way is by name.
When the object has a name you can access it directly from code behind and if you need to access it outside the class where it is defined then mark it as
public
.Because the
Name
An object defined within XAML is nothing more than a field/property within a class, only you don't define it with programming code but with tags. If you want to use that field/property then you will need to name it.
Naming an object is also useful for some binding scenarios where one object's binding is related to another's.
binding
For example you have a
Slider
and you want the value of the slider to modify the opacity of an objectImage
in that case you have to make the propertyOpacity
ofImage
do binding with the propertyValue
of theSlider
... and there is no way to do it decently but by assigning itName
to theSlider
.Creativity
Remember that a XAML is only half of a partial class, the other half is of course the code behind.
If you want to have a way to quickly access an object in your UI, you could then name it and expose it as
public
, i.e. a property within your class, also in codebehind you can encapsulate the way you access its properties and expose only what that you want as public properties.Sometimes I have had to allow a specific object to be accessed globally, in that case what I do is manage a static class throughout the app where I reference some objects whose access is important and I take care of assigning these static fields with the corresponding instance from the codebehind of a XAML, example
It seems simple but it is not, in the middle there can be real nightmares, but for basic cases it can always be a way out to change some specific property of the UI etc... that yes , whenever you reach this scenario you must be clear that your strategy of binding is incomplete and you are not managing the state of some things that should be part of the model (ViewModel).
and the keys
The
key
, as you have been told, are descriptors of an object in a resource group, if you think of the resource group this is nothing more than a collection of objects that I want to use in a certain scenario. It is no coincidence that they are called Dictionaries, because in the end that is what they are, dictionaries very similar to aDictionary<string, object
collection where you can access its objects using a key that acts as an index.You define the key when you have an object that you want to access as a resource, for example: