May 3

Written by: Michael Washington
5/3/2013 6:34 AM 

LightSwitch will allow you to easily create a popup to allow a user to select an item from a list in an associated table and to set a value.

You can see an example at this link. What is more difficult, is constraining that list of items presented based on business rules.

The Sample Application

In our sample application, we have a list of regions. There are three that are in the North. One of them in inactive.

When we click on a region record we can select the region (North, South, East, or West) and give the region option a name.

We can also indicate if the region is active (or not).

When we edit a Customer we can set their region.

We can now add Incidents for a Customer.

When we click the button to set the region option for the Customer, we only see active region options for the region the Customer is in.

When we select a region option in the Popup, it is set as the region option for the Incident.

Creating The Application

We create a normal Add/Edit screen.

We click the Add Data Item button, and add the RegionOptions collection.

We click Edit Query on the collection.

We create a query to implement our business rules.

We create a Region parameter for the query.

We click the Back button to return to the screen designer.

We specify the value for our parameter by clicking on it, and in the Properties, navigate to the Customer property of the Incident entity.

We select the CustomerRegion of the Customer entity.

In the screen designer, we will see a line showing the connection for the parameter when we click on it.

Next, we add a Popup.

We drag and drop the RegionOptions collection onto the Popup.

We delete the Customer section (because it is not needed).

We also delete the second column on the first tab (because it is not needed).

We add a new Button.

We set it to open the Popup.

We set “…” for the display name for the Popup.

We add Region Options to the first tab.

We change Region Options to only display the Summary.

Next, we want to set the Region Option when a user clicks on it in the Popup.

We click on the Region Options Set List in the Popup and in its Properties, we click the Item Tap action.

We create a method for the Action.

We right-click on the newly created method in the View Model and select Edit Execute Code.

We use the following code for the method:

 

myapp.AddEditIncidentNew.RegionOptionsSet_ItemTap_execute = function (screen) {
    // Get the list that is in the Popup
    var RegionOptionsSet = screen.findContentItem("RegionOptionsSet");
    // Get the selected item in the list
    var RegionOption = RegionOptionsSet.value.selectedItem;
    // update Region for the Incident 
    screen.Incident.setRegionOptions(RegionOption);
    //Close the Popup 
    screen.closePopup();
};

 

Simple Method

If you need to add additional items to the Popup such as a search within the list shown on the Popup the method shown will work for you.

However if a simple list is all you need, you don’t actually need to create the Popup or write any code.

We change the Region Option control to a Details Modal Picker.

In the Properties for the Modal Picker, we change the Choices to the RegionOptions collection (that has the query that implements the business rules).

When we run the program, a drop down appears that causes a Popup to show.

 

Download Code

The LightSwitch project is available at http://lightswitchhelpwebsite.com/Downloads.aspx

(you must have Visual Studio 2012 Update 2 installed to run the code)