MVVM绑定到实体框架中的外键属性

Question

I'm getting started with Entity Framework and need some help understanding the functionality between two Tables. To start with I have PhoneRecords and PhoneModels . Each PhoneRecord has a property called PhoneModelId that relates to one of the PhoneModels . In MySQL these properties are setup as a foreign key relationship.

Now I've loaded a sample of PhoneRecords into a DataGrid . I have a TextBox that I want to reflect the model on the PhoneRecord . At present my TextBox looks like so:

<TextBox Grid.Row="1" Grid.Column="1" Text="{Binding SelectedRecord.PhoneModelId}"/>

and, unsurprisingly, the Id is displayed instead of the Name of the PhoneModel . Usually without EntityFramework I would just have a property on the PhoneRecord itself called PhoneModelName or something similar which I would get using a JOIN when writing out my SELECT commands..

It seems to me that that method is old fashioned, and that Entity Framework is a powerful tool for getting around writing long CRUD operations. However, I am stuck in seeing how I am able to bind in MVVM to the PhoneModel name rather than using the PhoneModelId property on the PhoneRecord .

Answer 1

Try something like:

"{Binding SelectedRecord.PhoneModel.Name}"

I'm not sure which version of EF you're using or which flavour (code-first, DB first, code-first with existing database, etc.)... but...

In EF if you have an object that has a foreign key relationship it will attach that object to it's parent or child. So each PhoneRecord will have a PhoneModel object attached to it, and vice versa. If you're using code first, you'll have to code this relationship, if you're using DB first it should already exist int the model (EDMX) and you should be able to navigate to a PhoneModel from a PhoneRecord and back again.