How do I inherit from a base class and add another property?

Question

I have a class that's used to construct a request object to pass to an API:

public class BaseRequest
{
    public string messageId { get; set; }
    public string timestamp { get; set; }
    public string updatedAtMin { get; set; }
    public int page { get; set; }

    public BaseRequest(DateTime updatedAtMin, int page)
    {
        this.messageId = Guid.NewGuid().ToString();
        this.timestamp = DateTime.UtcNow.ToString("o");
        this.updatedAtMin = updatedAtMin.ToString("o");
        this.page = page;
    }
}

However, there is an edge case where an optional parameter needs to be added to the request object. My first thought was to inherit from the BaseRequest class but I can't see how to create this and make it syntactically correct.

public class CaseRequest : BaseRequest
{
    public bool extraParameter { get; set; }

    public CaseRequest(bool extraParameter) : base()
    {
        this.extraParameter = extraParameter;
    }
}

Error: There is no argument given that corresponds to the required formal parameter 'updatedAtMin' of 'BaseRequest.BaseRequest(DateTime, int)

Can anyone please help? Esssentially, I want to create an instance of the BaseRequest with the usual constructor but adding in the extraParameter.

Many thanks, and apologies for my woeful ignorance!

Answer 1

Your base class' constructor has parameters:

public BaseRequest(DateTime updatedAtMin, int page)

But you're not passing any values for those parameters:

base()

Ideally you would expand your constructor to accept those parameters and pass them along:

public CaseRequest(DateTime updatedAtMin, int page, bool extraParameter) : base(updatedAtMin, page)
{
    this.extraParameter = extraParameter;
}

You could also pass default values if you don't want the user to set them. Or create a parameterless constructor in the base class. Etc. As long as you pass something to satisfy a base constructor.

Answer 2

Your problem is simple as the error indicates.

There is no argument given that corresponds to the required formal parameter 'updatedAtMin' of 'BaseRequest.BaseRequest(DateTime, int)

You define a constructor in BaseRequest. This eliminates the default parameterless constructor. Which means...

public CaseRequest(bool extraParameter) : base()

does not find base() because base () does not exist.

YOu MUST accept the other parameter and pass them into the defined base to be syntatically correct.

Answer 3

you can try the following

public class BaseRequest
{
    public string messageId { get; set; }
    public string timestamp { get; set; }
    public string updatedAtMin { get; set; }
    public int page { get; set; }

    public BaseRequest(DateTime updatedAtMin, int page)
    {
        this.messageId = Guid.NewGuid().ToString();
        this.timestamp = DateTime.UtcNow.ToString("o");
        this.updatedAtMin = updatedAtMin.ToString("o");
        this.page = page;
    }

    public BaseRequest() {
    }
}

public class CaseRequest : BaseRequest
{
    public bool extraParameter { get; set; }

    public CaseRequest(bool extraParameter) : base()
    {
        this.extraParameter = extraParameter;
    }
}