DDD / Repository

Question

Hello,

I am very new to DDD. My SQL table contains a list of styles, every style has colors and sizes. Now, I am working on an application, where the user will see three dropdownlists, one for style, one for the color and one for the size. Now initially these dropdownlists are loaded with the distinct values. The user is then able to select a style and the system will then able to find all colors/sizes for that selected style. The user can do the same with the color and it will load the styles that match the selected color and the sizes. You get the idea.

These are my basic requirements. Now I was thinking to create a repository for the styles (StyleRepository) and have it load all styles, and when required load the child colors, and child sizes.

However as described in my app, I will also need to load the distinct colors or sizes. Now is it recommended to create three repositories instead StyleRepository, ColorRepository, SizeRepository or would I create a totally different Repository?

As said I am fairly new to this and would appreciate your suggestions.

Thank you

Answer 1

As colors in your case are actual colors used by styles, not just abstract color list (like in painting application), I would go with StyleRepository and addeed method like GetAllUsedColors().

Answer 2

Style appears to be your root aggregate object. That's what you build your Repository around.

Since each Style has a specific subset of Colors and Sizes that are allowed for that style, each Style should contain a list of Colors and Styles.

public class Style
{
   public IList<Color> Colors { get; set;}
   public IList<Size> Sizes { get; set;}
}

Your Repository is then going to have a FindAll() method to return all the Styles. Each Style has its own list of Colors and Sizes, so no need to hit the Repository again to get those. When the user selects a specific Style from a dropdown (hopefully you've bound the Style object) then you can just get the list of Colors and Sizes from the selected object and populate the other Dropdowns.

When a user chooses a specific Style, Color and Size, then I would assume that gets saved in a separate class, like a SelectedStyle class, which only contains one Color and Size property.

public class SelectedStyle
{
   public Color Color { get; set;}
   public Size Size { get; set;}
}