Sometimes it seems that the Name and x:Name attributes are interchangeable.
So, what are the definitive differences between them, and when is it preferable to use one over the other?
Are there any performance or memory implications to using them the wrong way?
There really is only one name in XAML, the x:Name. A framework, such as WPF, can optionally map one of its properties to XAML's x:Name by using the RuntimeNamePropertyAttribute on the class that designates one of the classes properties as mapping to the x:Name attribute of XAML.
The reason this was done was to allow for frameworks that already have a concept of "Name" at runtime, such as WPF. In WPF, for example, FrameworkElement introduces a Name property.
In general, a class does not need to store the name for x:Name to be useable. All x:Name means to XAML is generate a field to store the value in the code behind class. What the runtime does with that mapping is framework dependent.
So, why are there two ways to do the same thing? The simple answer is because there are two concepts mapped onto one property. WPF wants the name of an element preserved at runtime (which is usable through Bind, among other things) and XAML needs to know what elements you want to be accessible by fields in the code behind class. WPF ties these two together by marking the Name property as an alias of x:Name.
In the future, XAML will have more uses for x:Name, such as allowing you to set properties by referring to other objects by name, but in 3.5 and prior, it is only used to create fields.
Whether you should use one or the other is really a style question, not a technical one. I will leave that to others for a recommendation.
See also AutomationProperties.Name VS x:Name, AutomationProperties.Name is used by accessibility tools and some testing tools.
They are not the same thing.
x:Name is a xaml concept, used mainly to reference elements. When you give an element the x:Name xaml attribute, "the specified x:Name becomes the name of a field that is created in the underlying code when xaml is processed, and that field holds a reference to the object." (MSDN) So, it's a designer-generated field, which has internal access by default.
Name is the existing string property of a FrameworkElement, listed as any other wpf element property in the form of a xaml attribute.
As a consequence, this also means x:Name can be used on a wider range of objects. This is a technique to enable anything in xaml to be referenced by a given name.
x:Name and Name are referencing different namespaces.
x:name is a reference to the x namespace defined by default at the top of the Xaml file.
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Just saying Name uses the default below namespace.
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
x:Name is saying use the namespace that has the x alias. x is the default and most people leave it but you can change it to whatever you like
xmlns:foo="http://schemas.microsoft.com/winfx/2006/xaml"
so your reference would be foo:name
Define and Use Namespaces in WPF
OK lets look at this a different way. Say you drag and drop an button onto your Xaml page. You can reference this 2 ways x:name and name. All xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" and
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" are is references to multiple namespaces. Since xaml holds the Control namespace(not 100% on that) and presentation holds the FrameworkElement AND the Button class has a inheritance pattern of:
Button : ButtonBase
ButtonBase : ContentControl, ICommandSource
ContentControl : Control, IAddChild
Control : FrameworkElement
FrameworkElement : UIElement, IFrameworkInputElement,
IInputElement, ISupportInitialize, IHaveResources
So as one would expect anything that inherits from FrameworkElement would have access to all its public attributes. so in the case of Button it is getting its Name attribute from FrameworkElement, at the very top of the hierarchy tree. So you can say x:Name or Name and they will both be accessing the getter/setter from the FrameworkElement.
MSDN Reference
WPF defines a CLR attribute that is consumed by XAML processors in order to map multiple CLR namespaces to a single XML namespace. The XmlnsDefinitionAttribute attribute is placed at the assembly level in the source code that produces the assembly. The WPF assembly source code uses this attribute to map the various common namespaces, such as System.Windows and System.Windows.Controls, to the http://schemas.microsoft.com/winfx/2006/xaml/presentation namespace.
So the assembly attributes will look something like:
PresentationFramework.dll - XmlnsDefinitionAttribute:
[assembly: XmlnsDefinition("http://schemas.microsoft.com/winfx/2006/xaml/presentation", "System.Windows")]
[assembly: XmlnsDefinition("http://schemas.microsoft.com/winfx/2006/xaml/presentation", "System.Windows.Data")]
[assembly: XmlnsDefinition("http://schemas.microsoft.com/winfx/2006/xaml/presentation", "System.Windows.Navigation")]
[assembly: XmlnsDefinition("http://schemas.microsoft.com/winfx/2006/xaml/presentation", "System.Windows.Shapes")]
[assembly: XmlnsDefinition("http://schemas.microsoft.com/winfx/2006/xaml/presentation", "System.Windows.Documents")]
[assembly: XmlnsDefinition("http://schemas.microsoft.com/winfx/2006/xaml/presentation", "System.Windows.Controls")]
They're both the same thing, a lot of framework elements expose a name property themselves, but for those that don't you can use x:name - I usually just stick with x:name because it works for everything.
Controls can expose name themselves as a Dependency Property if they want to (because they need to use that Dependency Property internally), or they can choose not to.
More details in msdn here and here:
Some WPF framework-level applications
might be able to avoid any use of the
x:Name attribute, because the Name
dependency property as specified
within the WPF namespace for several
of the important base classes such as
FrameworkElement/FrameworkContentElement
satisfies this same purpose. There are
still some common XAML and framework
scenarios where code access to an
element with no Name property is
necessary, most notably in certain
animation and storyboard support
classes. For instance, you should
specify x:Name on timelines and
transforms created in XAML, if you
intend to reference them from code.
If Name is available as a property on
the class, Name and x:Name can be used
interchangeably as attributes, but an
error will result if both are
specified on the same element.
X:Name can cause memory issues if you have custom controls. It will keep a memory location for the NameScope entry.
I say never use x:Name unless you have to.
Name:
can be used only for descendants of FrameworkElement and FrameworkContentElement;
can be set from code-behind via SetValue() and property-like.
x:Name:
can be used for almost all XAML elements;
can NOT be set from
code-behind via SetValue(); it can only be set using attribute
syntax on objects because it is a directive.
Using both directives in XAML for one FrameworkElement or FrameworkContentElement will cause an exception: if the XAML is markup compiled, the exception will occur on the markup compile, otherwise it occurs on load.
The only difference is that if you are using user Controls into a control from Same Assembly then Name will not identify your control and you will get an error " Use x:Name for controls in the same Assembly".
So x:Name is the WPF versioning of naming controls in WPF. Name is just used as a Winform Legacy. They wanted to differentiate the naming of controls in WPF and winforms as they use attributes in Xaml to identify controls from other assemblies they used x: for Names of control.
Just keep in mind dont put a name for a control just for the sake of keeping it as it resides in memory as a blank and it will give you a warning that Name has been applied for a control buts its never used.
x:Name means: create a field in the code behind to hold a reference to this object.
Name means: set the name property of this object.
I always use the x:Name variant.
I have no idea if this affects any performance, I just find it easier for the following reason.
If you have your own usercontrols that reside in another assembly just the "Name" property won't always suffice. This makes it easier to just stick too the x:Name property.
It's not a WPF item but a standard XML one and BtBh has correctly answered it, x refers to the default namespace. In XML when you do not prefix an element/attribute with a namespace it assumes you want the default namespace.
So typing just Name is nothing more than a short hand for x:Name. More details on XML namespaces can be found at link text
The specified x:Name becomes the name of a field that is created in the underlying code when XAML is processed, and that field holds a reference to the object. In Silverlight, using the managed API, the process of creating this field is performed by the MSBuild target steps, which also are responsible for joining the partial classes for a XAML file and its code-behind. This behavior is not necessarily XAML-language specified; it is the particular implementation that Silverlight applies to use x:Name in its programming and application models.
Read More on MSDN...
When you declare a Button element in XAML you are referring to a class defined in windows run time called Button.
Button has many attribute such as background, text, margin, ..... and an attribute called Name.
Now when you declare a Button in XAML is like creating an anonymous object that happened to have an attribute called Name.
In general you can not refer to an anonymous object, but in WPF framework XAML processor enables you to refer to that object by whatever value you have given to Name attribute.
So far so good.
Another way to create an object is create a named object instead of anonymous object. In this case XAML namespace has an attribute for an object called Name (and since it is in XAML name space thus have X:) that you may set so you can identify your object and refer to it.
Conclusion:
Name is an attribute of a specific object, but X:Name is one attribute of that object (there is a class that defines a general object).
One of the answers is that x:name is to be used inside different program languages such as c# and name is to be used for the framework. Honestly that is what it sounds like to me.
My research is x:Name as global variable. However, Name as local variable. Does that mean x:Name you can call it anywhere in your XAML file but Name is not.
Example:
<StackPanel>
<TextBlock Text="{Binding Path=Content, ElementName=btn}" />
<Button Content="Example" Name="btn" />
</StackPanel>
<TextBlock Text="{Binding Path=Content, ElementName=btn}" />
You can't Binding property Content of Button with Name is "btn" because it outside StackPanel
Name can also be set using property element syntax with inner text, but that is uncommon. In contrast, x:Name cannot be set in XAML property element syntax, or in code using SetValue; it can only be set using attribute syntax on objects because it is a directive.
If Name is available as a property on the class, Name and x:Name can be used interchangeably as attributes, but a parse exception will result if both are specified on the same element. If the XAML is markup compiled, the exception will occur on the markup compile, otherwise it occurs on load.
I am completely noob in WPF. I have just opened MS Visual Studio Express 2013 Preview and I am trying to do some "Hello World!" app. I have noticed when I am adding a control to form, for example a TextBox, that control has no name assign.
Is this normal? And how can I change its properties from code?
In WPF, a control needs a name to be provided almost exclusively for the following reasons only:
The developer wants to reference the control in code-behind (frowned upon when using MVVM but sometimes necessary)
When the developer will be passing the XAML to a testing team that is using an automated UI testing tool
When a Binding on another control is using ElementName to reference a property on that control.
If it's not one of those, there's really no need to name your controls. You'll find, once you start using MVVM as your principal design pattern, that you rarely need to know the names of your controls in code. Start getting used to changing properties in XAML, not code.
You should use the Name attribute and provide a unique identifier:
<TextBox Name="UniqueName">
Value
</TextBox>
Assigning the Name value in code could only be achieved if you found a way to actually locate the control without a name in the first place - a little long-winded rather than using the markup, unless, that is, you're adding the controls to the window dynamically anyway, and so already have a direct reference to the element.
Add "Name" attribute
Msdn doc :
http://msdn.microsoft.com/en-us/library/system.windows.frameworkelement.name.aspx
that control has no name assign. Is it normal? How can I change its properties from code
after creating the control, you can access all it's properties like
Textbox tb = new TextBox();
tb.Name = "textBox1";
tb.Text = "Hello world";
someStackPanel.Children.Add(tb);
Looking for a way to automatically verify, using unit-tests for example, that all controls in my WPF application are set to Binding.
I'm using data-binding to enable localization in the application.
For example, a TextBlock control in a view will have it's Text property binding to 'SomeLocalizedLabel' property in the view model.
I need to make sure that I won't miss any control, and all my 'TextBlock' controls have their 'Text' property bound to something.
I can check the correctness of the localization itself in the ViewModel level.
I can check that all public ViewModel properties are bound to something in the view using the Caliburn.Testability assembly or some other method.
The thing that missing here is to test the View level.
UI testing framework is not the solution I'm looking for, because I wish for something that can be written and executed fast.
See my post here:
How to check if a XAML element supports AutomationId attribute
You could use the mechanisms mentioned to go through all your XAML and look at the Text properties of elements, and decide if they have missed a Binding.
LocBaml is a tool that goes through the XAML to extract localizable properties....your rolling your own localization technique...but I'm sure you can adapt that to extract check "Text" properties and see if they have a binding, then produce a report where they are not.
How can I find and access to Elements which are bind to an object in XAML ?
Edit : Let's say I have a EmployeeViewModel which is assigned to EmployeeView's DataContext and a EmployeeModel inside my EmployeeViewModel, I want to know which properties of my model bounded to View's Framework Elements (Controls) also I want to have an access to each control bounded to my model properties.
UPDATE: In light of the question being clarified by SaberAmani in that he is trying to add validation to his models and show a validation summary..see the links below.
http://msdn.microsoft.com/en-us/magazine/ff714593.aspx
http://codeblitz.wordpress.com/2009/05/12/wpf-validation-summary-control/
http://wpfvalidation.codeplex.com/
http://f10andf11.blogspot.co.uk/2012/02/wpf-validation-summary-control.html
For reference for people that want to discover Bindings:
You don't mention if your XAML is in WPF, Silverlight, Metro or Phone7 (thus you may be more restricted in what you can do).
There seem to be a few possible ways to do what you want:
Reflection
MarkupObject / MarkupWriter
TypeDescriptor+DependencyPropertyDescriptor
Custom Binding Markup Extension
Take a look at this link.
http://blog.spencen.com/2008/05/02/how-to-get-a-list-of-bindings-in-wpf.aspx
He uses reflection and suggests this is the classical way to do it...but also mentions MarkupWriter as another possibility. NOTE: the reflection method doesn't discover Attached Properties which may have bindings.
Here are some links that use MarkupWriter...this would allow you to discover the attached properties.
http://www.codeproject.com/Articles/21139/An-XAML-Serializer-Preserving-Bindings
http://blogs.msdn.com/b/marlat/archive/2009/05/24/getbindingexpression-a-good-way-to-iterate-over-all-dependency-properties-in-visual-tree-in-silverlight-3.aspx
Related links:
Retrieve all Data Bindings from WPF Window
Getting list of all dependency/attached properties of an Object
http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/580234cb-e870-4af1-9a91-3e3ba118c89c
you could use reflection to loop through properties and use FrameworkElement.GetBindingExpression on each property to build, for a given Framework element, all its bindings.
http://msdn.microsoft.com/en-us/library/system.windows.frameworkelement.getbindingexpression
I'm looking for a data-driven WPF property grid/editor.
Most property grids appear to work using reflection to figure out the CLR properties on your class. Those properties are then displayed in the grid with editors that are specific for the type of the property.
However I don't have a specific class that I want to plug into the property grid. All I have is data, specifically a collection of name/value pairs. I want to put this collection into the grid and have a editor that is specific for the value type of each pair.
Does anyone know of an existing property grid/editor control that supports data-driven properties?
Also if it looks like the property grid/editor in Blend I won't complain ;)
I've never used it, but from what I've read about the PropertyTools for WPF on codeplex.com supports dynamically editting the current selected object.
http://propertytools.codeplex.com/