创建对象后设置其属性

Question

I have an object with 2 properties:

public class Request
{
    public int TypeId { get; set; }
    public bool isApproved { get; set; }
}

What I wish to happen is, if TypeId equals 1 , I want isApproved to equal false , otherwise I want it to equal true when I create a new object. I tried the following but it was set to true for both of my objects, where I do the rule in the constructor:

public Request() {
    if(this.TypeId == 1) {
        this.isApproved = false;
    }
    this.isApproved = true;
}

var request = new Request() {
    TypeId = 1
}

var request2 = new Request() {
    TypeId = 2
}

I know why this occurred, its because TypeId hasn't been set when the constructor is called, so it defaults to true . Is there anyway I can set this automatically once TypeId has been set on a newly created object?

Edit

I'd also like to have the option to change isApproved manually at a later date, so if it was set to false I can change it to true without the automatic rule I set affecting it

Answer 1

I would put the logic in the IsApproved getter, and make it a read only value:

public class Request
{
    public int TypeId { get; set; }
    public bool IsApproved 
    { 
        get
        {
            return this.TypeId != 1;
        }
}

Oh, also C# code standards usually specify that properties should be CamelCased.

Edit:

I'd also like to have the option to change isApproved manually at a later date, so if it was set to false I can change it to true without the automatic rule I set affecting it

You would want to set it with a constructor then. (As Alex already suggested)

public class Request
{
    public int TypeId { get; set; }
    public bool IsApproved { get; set; }

    public Request(int typeId)
    {
        this.TypeId = typeId;
        this.IsApproved = typeId != 1;
    }
}

Answer 2

Try changing

public int TypeId { get; set; }

to

public int _typeId;

public int TypeId 
{
    get
    {
        return _typeId;
    }
    set
    {
        _typeId = value;
        isApproved = value != 1;
    }
}

Answer 3

C# 4.0 allows you to assign a default value to method parameters, and makes you able to do this:

public Request(int TypeId = 1)
{
    approved = TypeId != 1;
}

usage:

var request = new Request(2); // approved = true
var request2 = new Request(1); //approved = false

Answer 4

public class Request
{
    private int _typeId;
    public int TypeId { 
        get { return _typeId; }
        set {
            _typeId = value;
            isApproved = _typeId != 1;
        }
    }
    public bool isApproved { get; private set; }
}

Answer 5

public class Request
{
    private int _typeId;
    public int TypeId 
    get
    {
        return _typeId;
    }
    set
    {
        isApproved = value != 1;
        _typeId = value;
    }

    public bool isApproved { get; set; }
}