WPF MVVM ObservableCollection/DataGrid Multiple Sql Tables

Question

Ok...as I continue to muddle my way through teaching myself... Here is my latest question. Ha! I have a WPF App using MVVM and three different sample MySQL tables as follows:

BOOKINGS

Booking_ID_Num | Book_Type_Num | Fac_ID_Num |
---------------|---------------|------------|
       1       |       1       |     2      |
       2       |       2       |     3      |
       3       |       1       |     1      |

BOOKING_TYPES

Book_Type_Num |  Book_Type |
--------------|------------|
      1       |  Full Time |
      2       | Singe Case |

FACILITIES

Fac_ID_Num | Facility_Name |
-----------|---------------|
    1      |   Joe's Shop  |
    2      |    MedRX      |
    3      | Grocery Story |

I'm going to try to explain this as succinctly as possible, feel free to criticize... I would like to fill an ObservableCollection and pass that ObservableCollection to a DataGrid. I know how to fill an ObservableCollection through a Model Class, but I don't know how to fill with multiple tables. In this example, I would like to have an Observable Collection in the ViewModel passed to a DataGrid that is structured like this:

Booking_ID_Num | Book_Type_Num |  Book_Type  | Fac_ID_Num | Facility_Name |
---------------|---------------|-------------|------------|---------------|
       1       |       1       |  Full Time  |      2     |     MedRx     |
       2       |       2       | Single Case |      3     | Grocery Store |
       3       |       1       |  Full Time  |      1     |   Joe's Shop  |

Basically, I want to use the Book_Type and Facility_Name in the final solution without having to make any adjustments in the MySQL database like creating a new "view" or something. Does that make sense? This site has been wonderful in helping me learn. Any help on this vague question would be greatly appreciated. Thank you so much!

Jan Paolo Go · Accepted Answer · 2017-11-30 18:15:51Z

1

Create separate classes that will represent data in your database and data on your DataGrid.

For example:

public class Booking
{
    public int BookingIDNum { get; set; }
    public int BookTypeNum { get; set; }
    public int FacIDNum { get; set; }
}

public class BookingType
{
    public int BookTypeNum { get; set; }
    public string BookType { get; set; }
}

public class Facility
{
    public int FacIDNum { get; set; }
    public string FacilityName { get; set; }
}

public class ViewData
{
    public int BookingIDNum { get; set; }
    public int BookTypeNum { get; set; }
    public string BookType { get; set; }
    public int FacIDNum { get; set; }
    public string FacilityName { get; set; }

    public static ViewData From(Booking booking, BookingType bookingType, Facility facility)
    {
        return new ViewData
        {
            BookingIDNum = booking.BookingIDNum,
            BookingTypeNum = booking.BookingTypeNum,
            FacIDNum = booking.FacIDNum,
            BookType = bookingType.BookType,
            FacilityName = facility.FacilityName
        };
    }
}

on the example above, the classes Booking, BookingType, and Facility represents data in your database while ViewData will be the class you bind on your DataGrid.

edited Nov 30, 2017 at 18:15

answered Nov 30, 2017 at 4:44

Jan Paolo Go

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5 Comments

Progolfer79 Over a year ago

Ok. That somewhat makes sense. So how would I fill each property from the database? Do I put the MySQL data pull method in the "set" of each property or is there something like a "foreach" method I can use with the ViewData class? I apologize for my ignorance. Trying to learn.

Jan Paolo Go Over a year ago

See edited answer. ViewData.From method. Does that answer your question?

Progolfer79 Over a year ago

I'm sorry... I'm so confused and probably way over thinking this... how do I get the data from the MySQL database into the Model Classes "Bookings", "BookingType" and "Facility"? I thought the Model Classes weren't supposed to have any function. No? If not, how do I get the MySQL data into the "ViewData" class? Finally, how do all the different properties relate to each other so I'm not left with 3 or 4 different sets of lists/collections in the columns. IE: when Fac_ID_Num is 1, "Joe's Shop" and not just the 3rd value of Facility_Name?

Progolfer79 Over a year ago

I'm an idiot... I know. But I'm trying really hard to learn. Ha! :-)

Jan Paolo Go Over a year ago

Then, you should implement another class (or classes) that will get data from your database and turn it into Booking, BookingType, and Facility

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