Microsoft Silverlight

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6579 points

Re: Displaying Multiple data sets held in single data set

07-02-2009 12:49 PM |

Do you need paging? If you need paging then you will need multiple DomainDataSources, one for each listbox. If you don't need paging then another option would be to get rid of the DomainDataSource completely and switch to using a ViewModel instead. Changing your database design is that last thing you should try.

-Colin Blair

http://www.RiaServicesBlog.net : The Elephant Guide to RIA Services
SLColinBlair on Twitter

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9 points

Re: Displaying Multiple data sets held in single data set

07-02-2009 2:26 PM |

ColinBlair:
Changing your database design is that last thing you should t

- exactly right, thats just what I am trying to avoid

To be more specific lets say I have a table tblMeal it contains columns

id - auto number
mealType - int
mealTime - DateTime
calories - int

the meal type column relates to breakfast, lunch, dinner etc so 0 might = breakfast, 1 = lunch etc.

I have another table - lets say tblPeoplesMeals it would then hold a reference to a person and their meals so one person in one day may end up with three entries in the tblMeal table

Now to display the data, in a datform I want to be able to display seperately breakfasts, lunches and dinners
I want to start with the person, display a couple of fields about them and then using the power of EF display the meal data but seperately.
I can automatically display all of the data because my Load function calls the data for the person I am currently looking at.

The problem I am trying to solve is how to seperately display the data - so for example in seperate list boxes.

Any suggestions on how I could do that?

Thanks

Nic

Contributor

6579 points

Re: Displaying Multiple data sets held in single data set

07-02-2009 2:57 PM |

Well, you could use a DataGrid. Something like:

<data:DataGrid ItemsSource="{Binding tblPeoplesMeals}" AutoGenerateColumns="False">
                <data:DataGrid.Columns>
                <data:DataGridTemplateColumn>
                    <data:DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                            <DataForm>
                            </DataForm>
                        </DataTemplate>
                    </data:DataGridTemplateColumn.CellTemplate>
                </data:DataGridTemplateColumn>
</data:Datagrid>

I was originally thinking of just a plain ItemsControl but it would be hard to control the ordering of the meals without the DataGrid's internal sorting system.

-Colin Blair

http://www.RiaServicesBlog.net : The Elephant Guide to RIA Services
SLColinBlair on Twitter

Member

9 points

Re: Displaying Multiple data sets held in single data set

07-02-2009 4:01 PM |

Apologies if I am being dense (it wouldn't be the first time Smile ) but how would that allow me to show the data seperately.

At the moment I am displaying the data in a templated listbox. It shows all of the data and I could order it as necessary, but what I would like to do is display it in say three controls. One each for breakfast, lunch and dinner. So breakfast would be in one list box or grid, lunch in another and dinner in another still. Is there someway of applyin a filet to each one without it effecting the overall content of the entity set?

[Thanks for your help on this BTW!]

Nic

Contributor

6579 points

Re: Displaying Multiple data sets held in single data set

07-02-2009 4:37 PM |

(July 7 - Historical note: this thread split after this solution was created. A better solution is in that second thread.)

Well, I am having trouble figuring out what the difference is between "seperate controls" and your templated listbox. The only difference to me is that seperate controls are hard coded and the listbox isn't, they both display seperate controls for each meal, you just have to specifiy what that control looks like.

Anyway, here is what I usually end up doing for something like this. I would add client side properties through a partial class onto the Person object. In this case you want Person.Breakfast, Person.Lunch, and Person.Dinner. Through a partial class on the Person object, just add in properties that do LINQ statements against the PersonMeals and then return the meal. It would look something like this:

namespace The.Correct.Namespace
public partial class Person
{
    public Meal Breakfast
    {
        get
        {
            return (from pm in PersonMeals
                    where pm.Meal.MealTypeId = 1
                    select pm.Meal).SingleOrDefault();
        }
    }
    public Meal Lunch
    {
        get
        {
            return (from pm in PersonMeals
                    where pm.Meal.MealTypeId = 2
                    select pm.Meal).SingleOrDefault();
        }
    }
    public Meal Dinner
    {
        get
        {
            return (from pm in PersonMeals
                    where pm.Meal.MealTypeId = 3
                    select pm.Meal).SingleOrDefault();
        }
    }
}

-Colin Blair

http://www.RiaServicesBlog.net : The Elephant Guide to RIA Services
SLColinBlair on Twitter

Member

9 points

Re: Displaying Multiple data sets held in single data set

07-02-2009 4:59 PM |

By seperate controls I mean literally three different list boxes. One each for breakfast, lunch and dinner.

The EntitySet loads the data for all three. So each time I bind the different controls I get all three meals shown in each one.
So for example, in your earlier grid sample code I get the three meals listed in each instance of the grid control.

My XAML page starts with by binding to a single record held in an EntitySet. This then links through to multiple records by traversing the Foreign Keys in the database, hence my ability to easily display the three records. If I create new methods in the DomainService to filter per meal the EntitySet for meal data is then only populated with the data from the last LoadMealsByType call.
If I create seperate methods to fill datasets I don't seem to be able to then get them to synch with the initial record being bound too (if I can get them to display at all)

I feel like there is some missing key which will make all this very clear - but right now I am stumped!

I will work up a small demo tomorrow to link here to see if that helps with asking my question.

Thanks for your help so far Colin, my appreciated.

Nic

Contributor

6579 points

Re: Displaying Multiple data sets held in single data set

07-02-2009 5:23 PM |

The partial class properties from my previous post should do what you want, they have nothing to do with the previous DataGrid solution.

-Colin Blair

http://www.RiaServicesBlog.net : The Elephant Guide to RIA Services
SLColinBlair on Twitter

Member

9 points