JSONPropertyBinding in SAP UI5 MVC framework implementation

In the SAP UI5 application, no matter whether XML view or JavaScript view code is used for data binding of JSON model, an JSONPropertyBindinginstance of will be automatically generated at the bottom layer.

JsonPropertyBinding.js is a file in the SAP UI5 framework, which plays an important role in the data binding system of SAP UI5. Specifically, it's the part of JSONModel that handles property binding for JSON data. In SAP UI5, property binding is a mechanism for linking data in the model with specific properties of UI controls. For example, we can valuebind the input field's property to a specific field in the model. This way, when the data in the model changes, the display of the UI controls is automatically updated.

In the data binding system of SAP UI5, JsonPropertyBinding.js provides the following functions:

1. Get the binding value: JsonPropertyBinding.js provides getValuethe function, which can be used to get the current value of the bound property.

2. Set Bound Value: setValueFunctions can be used to set the value of a bound property. When you setValueset a new value through the function, the display of the UI control will be automatically updated.

3. Monitor data changes: JsonPropertyBinding.js provides attachChangeand detachChangefunctions, which can be used to monitor data changes in the model. attachChangeThe registered callback function is called when the value of the bound property changes .

For example, suppose we have a JSONModel with the following data:

{
    
    
  "person": {
    
    
    "name": "John Doe",
    "age": 30
  }
}

We can create a property binding that namebinds the field to the property of a Label control text:

var oLabel = new sap.m.Label();
var oModel = new sap.ui.model.json.JSONModel({
    
    
  person: {
    
    
    name: 'John Doe',
    age: 30
  }
});
sap.ui.getCore().setModel(oModel);
oLabel.bindProperty('text', '/person/name');

In this example, person.namethe text of the Label control is automatically updated when the value of is changed. This is what JsonPropertyBinding.js does in SAP UI5.

In general, JsonPropertyBinding.js plays an important role in the data binding system of SAP UI5. It provides a convenient way to bind the data in the model to the properties of the UI controls, so that when the model's data changes, the display of the UI controls can be automatically updated. This greatly simplifies the synchronization of data and UI, allowing developers to focus more on the implementation of business logic without worrying about the synchronization of data and UI.