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This article mainly introduces the relevant knowledge of "what is the binding and use of the MVVMLight project". The editor shows you the operation process through the actual case, the operation method is simple and fast, and the practicality is strong. I hope this article "what is the binding and use of the MVVMLight project" can help you solve the problem.

1. Bind:

It mainly includes two kinds: element binding and non-element binding.

1. Element binding:

Is the simplest form of binding, the source object is an element of WPF, and the properties of the source object are dependency properties.

According to our previous knowledge, dependency properties have built-in change notification support. So when we change the value of the dependency property in our source object, the binding property in the target object is updated immediately.

To rewrite the examples in the above section, we do not need to define additional globally exposed properties to support the display of data.

As follows:

TextBlock binds an element named WelcomeText and points Path to the Text attribute, so its value changes as WelcomeText changes.

2. Non-element type binding: 2.1 Source attribute:

Bind specific data objects, such as system information and resource data we define.

Define global resources under Window

Red

Apply to the view

Results:

2.2 RelativeSource attribute:

Set this property to point to the source destination based on the relative relationship of the current target object. For example, get some data such as the parent object, sibling object, or other properties of the current object.

The code is easy to understand. When creating RelativeSource here, there are four types of mode schemas:

Mode member name description FindAncestor

References the parent chain of the data-bound element. This can be used to bind to a specific type of parent or its subclasses. To specify AncestorType and / or AncestorLevel, this is the mode that should be used.

PreviousData

Allows you to bind the last data item (not the control that contains the data item) in the currently displayed list of data items.

Self

References the element on which you are setting the binding and allows you to bind one attribute of that element to other attributes of the same element.

TemplatedParent

References an element to which a template is applied, where a data binding element exists in the template. This is similar to setting TemplateBindingExtension and applies only if Binding is inside the template.

Note: AncestorType refers to the type of object to be found, AncestorLevel represents the location of the search level, and if it is 3, the first two discovered elements are ignored.

Results:

2.3 DataContext attributes:

If you want to bind an object to a view block or composite element consisting of multiple elements, it is easier to develop and maintain it with DataContext. As follows

2. Various usage scenarios of binding:

Data binding has common control binding applications, such as drop-down boxes, checkboxes, normal text boxes, date boxes, etc.

Complex bindings include data list binding, user control information binding and so on, such as ListBox,DataGrid,UserControl binding.

1. Drop-down box:

View Code:

Model Code:

Public class ComplexInfoModel:ObservableObject {private String key; / Key value / public String Key {get {return key;} set {key = value; RaisePropertyChanged (() = > Key);}} private String text / Text value / public String Text {get {return text;} set {text = value; RaisePropertyChanged (() = > Text);}

ViewModel Code:

# region drop-down box related private ComplexInfoModel combboxItem; / drop-down box check message / public ComplexInfoModel CombboxItem {get {return combboxItem;} set {combboxItem = value; RaisePropertyChanged (() = > CombboxItem);}} private List combboxList / drop-down box list / public List CombboxList {get {return combboxList;} set {combboxList = value; RaisePropertyChanged (() = > CombboxList);}} # endregio

Description: CombboxItem is a global attribute, which acts in the data context of the current page, and the content displayed in the result points to the selected value in the drop-down box to achieve the purpose of sharing one data.

There are four things to note here: ItemsSource: data source; SelectedItem: selected item; DisplayMemberPath: the value displayed when binding; and SelectedValuePath: the value of key when binding.

Results:

2. Check box

Note: note that two attributes are used here: SingleRadio,IsSingleRadioCheck, one to display the contents of the checkbox, and one to indicate whether it is selected or not.

Results:

3. Combine the checkbox

We usually use a combination of check boxes to indicate the only option, such as gender includes men and women, but only one can be selected. More scenarios contain multiple options, but can only be singled, so you need to do a group of radio boxes.

TreeInfo);}} # endregion

Results:

6 、 ListBox

When we need to use circular list content and have a high degree of templating, it is recommended to use ListBox for binding.

View Code:

ViewModel Code:

# region ListBox template private IEnumerable listBoxData; / LisBox data template / public IEnumerable ListBoxData {get {return listBoxData;} set {listBoxData = value;RaisePropertyChanged (() = > ListBoxData);}} # endregion

Initial data:

Private void InitListBoxList () {ListBoxData = new ObservableCollection () {new {Img= "/ MVVMLightDemo;component/Images/1.jpg", Info= "Cherry"}, new {Img= "/ MVVMLightDemo;component/Images/2.jpg", Info= "Grape"}, new {Img= "/ MVVMLightDemo;component/Images/3.jpg", Info= "Apple"}, new {Img= "/ MVVMLightDemo Component/Images/4.jpg ", Info=" kiwifruit "}, new {Img=" / MVVMLightDemo;component/Images/5.jpg ", Info=" lemon "},}

Results:

7. Set binding of user controls:

ListBox's list binding is far from meeting the needs of our actual work.

For the sake of flexibility, reusability, and code simplification, you need to ensure that a single element in a circular list is a separate element fragment, similar to a partial view in Web. At this point, it is much better to use user controls.

Let's first write a user control and set its style and bound property values, respectively, as follows:

Register on the target view page and use:

Xmlns:Content= "clr-namespace:MVVMLightDemo.Content"

Results:

This is the end of the content about "what is the binding and use of the MVVMLight project". Thank you for reading. If you want to know more about the industry, you can follow the industry information channel. The editor will update different knowledge points for you every day.

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