C#: How to set default value for a property in a partial class?

Question

Hello,

I'm very new to C# so please bear with me...

I'm implementing a partial class, and would like to add two properties like so:

public partial class SomeModel
{
    public bool IsSomething { get; set; }
    public List<string> SomeList { get; set; }

    ... Additional methods using the above data members ...
}

I would like to initialize both data members: IsSomething to True and SomeList to new List<string>(). Normally I would do it in a constructor, however because it's a partial class I don't want to touch the constructor (should I?).

What's the best way to achieve this?

Thanks

PS I'm working in ASP.NET MVC, adding functionality to a a certain model, hence the partial class.

Answer 1

The first property (IsSomething) is a boolean. It will be false by default.

The second property, since it's a reference type, will default to null without any effort on your part. You don't need to touch the constructor, since reference types (classes) will automatically start off as null in .NET.

If you wanted to use a non-default value, you'd have two options -

First, use a backing storage field:

private bool isSomething = true;
public bool IsSomething {
    get { return this.isSomething; }
    set { this.isSomething = value; }
}

Second option - add it to the constructor.

Note that the first option has no extra overhead - it's basically what the compiler does when you use an automatic property.

Answer 2

Automatically implemented properties can be initialized in the class constructor, but not on the propery itself.

public SomeModel
{
    IsSomething = false;
    SomeList = new List<string>();
}

...or you can use a field-backed property (slightly more work) and initialize the field itself...

private bool _IsSomething = false;
public bool IsSomething
{
    get { return _IsSomething; }
    set { _IsSomething = value; }
}

Update: My above answer doesn't clarify the issue of this being in a partial class. Mehrdad's answer offers the solution of using a partial method, which is in line with my first suggestion. My second suggestion of using non-automatically implemented properties (manually implemented properties?) will work for this situation.

Answer 3

Both your properties will already have the default values you require.

There is nothing wrong with having a constructor in a partial class. Partial classes are in no way special, aside from the fact that their source code is spread across multiple files/declarations.

Answer 4

You can't have two constructors in two parts of a partial class. However, you can use partial methods to accomplish something like it:

// file1:
partial void Initialize();
public Constructor() {
    // ... stuff ... initialize part 1
    Initialize();
}

// file2:
void Initalize() {
    // ... further initializations part 2 might want to do
}

If no parts of a partial class defines the partial method, all calls to it would be omitted.

Answer 5

To this, don't use automatic property but the old way

YourType _yourParameter = yourDefaultValue;
public YourType YourParameter
{
   get{return _yourParameter;}
   set{_yourParameter=value;}
}