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Asked: 2026-06-15T14:01:59+00:00

I am new to VS-Lightswitch 2012 and also new to silverlight. In a lightswitch

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I am new to VS-Lightswitch 2012 and also new to silverlight.
In a lightswitch database I want to store tables of measured values.
Each table of MeasuredValues has a certain Unity.
So I have a table of Unities (like “m”, “mm”, “°C”) and each Unity has a table of possible UnityConversions (like “mm to m”, “mm to cm”). e.g. the Unity “m” has no conversion “m to °C” because this makes no sense at all. Each UnityConversion has a Unity it ConvertsTo.
A Unityconversion e.g. is: 0.00112m = 1.12mm

So when the user creates or edits the table of measured values he should be able to select the unity out of all existing Unities.
But when the Unity has to be converted it should only be possible to convert the value into the suitable Unity out of the table of UnityConversion of the current Unity.
So far so good all tables are defined. But how to do the UnityConversion thing?
I guess the easiest way would be to create a button below the Unity of the MeasuredValue that brings up a “Modal Window Picker” where the user can select the UnityConversion.

But how to fill a “Modal Window Picker” with the UnityConversions of the current Unity?
I have tried the “Modal Window Picker” it shows all existing Unities, but instead it should show the possible UnityConversions.

that’s where I stick, any idea is welcome thank you in advance

Oops
++++ Edit 14.Dec.2012 ++++

MValue
+-Id: Integer
+-Value: Double
+-Unity: Unity (relationship)
Unity:
+-Id: Integer
+-Name: String
+-ShortName: String
+-Conversions: collection of UnityConversion (relationship)
+-Converts     collection of UnityConversion (relationship)
+-MValues      collection of MValue (relationship)
UnityConversion:
+-Id: Integer
+-Name: String
+-Factor: Double
+-ConvertTo: Unity (relationship)
+-Unities:   Unity (relationship)
the relationship between Unity and UnityConversion is doubly so it looks like:
Unity                        UnityConversion
+-Conversions(visible) -------> +-Unities    (invisi.)
+-Converts   (invisi.) <------- +-ConvertsTo (visible)

My question: the double relationship is possible to do, but is it allowed to do it?
if it is allowed, why does the screendesigner, when creating a new screen for MValuesListDetail, not show the details UnityConversions?

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1 Answer

  1. Editorial Team

    It’s easy to do, but a bit lengthy to explain. You’ll need to add a parametrised query, with an integer parameter, based on the UnityConversion table (see Creating a Parameterized Query).

    In the screen designer:

    • Click on Add Data Item Select Query, then the name of the parametrised query that you created
    • Click on the added query, & expand Query Parameters (see
      Provide a Value to a Query Parameter)
    • Click on the name of the integer parameter that you added earlier
    • In the Properties pane, enter the binding value (Me.MeasuredValueProperty.ID)
    • Click on the ACB control (AutoCompleteBox) & in its properties, change the Choices value from Auto to the name of your parametrised query

    This should restrict the values in the UnityConversion property to values that are appropriate for the selected Unity.

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