Using the Fetch functions

The following are two examples of how to apply the Fetch and FetchOne functions in practice.

Using Fetch to retrieve entity records in Edit Grid controls

Use the Fetch function to retrieve all entity records from a Data Service entity, in conjunction with a tabular control such as Edit Grid.

1. Add an entity to your app:
   1. Select Add any.
   2. Select Entity.
   3. Select a tenant.
   4. Select the entity you want to add to your app, then Add.
2. 向应用程序添加“编辑网格”控件：
   1. 选择“添加控件”。
   2. Select Display.
   3. Select Edit Grid, and drag it to an area in your app.
3. Bind the Edit Grid control to your entity:
   1. In the Properties panel, on the General tab, select the Additional resources button adjacent to Data source.
   2. Select Query builder.
   3. Select the entity you want to use, then Save. The system automatically prepares a Fetch VB expression.
4. Preview or run your app.

When you preview your app, the Edit Grid control is populated with all of the records from your entity.

Using the FetchOne VB function to retrieve an entity record and display it in a Label control

Use the FetchOne function to retrieve a single record from a Data Service entity and use it in display controls, such as the Label control, in your apps.

1. Add an entity to your app:
   1. Select Add any.
   2. Select Entity.
   3. Select a tenant.
   4. Select the entity you want to add to your app, then Add.
2. Add a Label to your app:
   1. 选择“添加控件”。
   2. Select Display.
   3. Select Label, and drag it to an area in your app.
3. Add a variable to your app:
   1. Select Add any.
   2. Select Variable.
   3. Give your variable a name.
   4. Under Type, select your entity, then Save.
4. Add a rule to the main page of your app:
   1. Select the main page of your app.
   2. In the Properties panel, select Events.
   3. Under Loaded, select Create rule.
5. Bind the rule to your variable:
   1. Select Set value.
   2. Under Item to set, select the variable you added in step 3.
   3. Select Value, then Query builder.
   4. Select your entity, then Save. The system automatically prepares a Fetch VB expression.
   5. Under Value, select the expression, then replace Fetch with FetchOne.
6. Bind the Label to the variable:
   1. Select Add control, then Display.
   2. Select Label, and drag it to an area in your app.
   3. In the Properties panel, select the Open resources button adjacent to the Text field.
   4. 选择“表达式编辑器”。
   5. In the Expression editor, add the name of your entity followed by the name of a field in your entity. Separate the two with a period:
      Entity.Field
7. Preview or run your app.

When you run the app, the Label is automatically populated with a single record from the entity field you specified.