C# – An object reference is required for the non-static field, method, or property

asp.netcincludeinheritanceobject

So I have two functions and I'm getting an interesting problem. Essentially I'm aiming to make my code more portable in an easily includeable cs file.

Here's said cs file:

namespace basicFunctions {
public partial class phpPort : System.Web.UI.Page {
    public string includer(string filename) {
        string path = Server.MapPath("./" + filename);
        string content = System.IO.File.ReadAllText(path);
        return content;
    }
    public void returnError() {
        Response.Write("<h2>An error has occurred!</h2>");
        Response.Write("<p>You have followed an incorrect link. Please double check and try again.</p>");
        Response.Write(includer("footer.html"));
        Response.End();
    }
}
}

Here is the page that is referencing it:

<% @Page Language="C#" Debug="true" Inherits="basicFunctions.phpPort" CodeFile="basicfunctions.cs" %>
<% @Import Namespace="System.Web.Configuration" %>

<script language="C#" runat="server">
void Page_Load(object sender,EventArgs e) {
    Response.Write(basicFunctions.phpPort.includer("header.html"));
    //irrelevant code
    if ('stuff happens') {
        basicFunctions.phpPort.returnError();
    }
    Response.Write(basicFunctions.phpPort.includer("footer.html"));
}
</script>

The error I'm getting is the one listed above, namely:

Compiler Error Message: CS0120: An object reference is required for the non-static field, method, or property 'basicFunctions.phpPort.includer(string)'

Best Answer

You need an instance of your phpPort class as it and all the methods you have defined on it are not static.

Since you are on the aspx page that inherits from this class, when it loads it already is an instance of the class and you can call the methods on it directly.

You need to modify your code to use the functions directly:

void Page_Load(object sender,EventArgs e) {
    Response.Write(includer("header.html"));
    //irrelevant code
    if ('stuff happens') {
        returnError();
    }
    Response.Write(includer("footer.html"));
}

Related Solutions

C# – the difference between a field and a property

Properties expose fields. Fields should (almost always) be kept private to a class and accessed via get and set properties. Properties provide a level of abstraction allowing you to change the fields while not affecting the external way they are accessed by the things that use your class.

public class MyClass
{
    // this is a field.  It is private to your class and stores the actual data.
    private string _myField;

    // this is a property. When accessed it uses the underlying field,
    // but only exposes the contract, which will not be affected by the underlying field
    public string MyProperty
    {
        get
        {
            return _myField;
        }
        set
        {
            _myField = value;
        }
    }

    // This is an AutoProperty (C# 3.0 and higher) - which is a shorthand syntax
    // used to generate a private field for you
    public int AnotherProperty { get; set; } 
}

@Kent points out that Properties are not required to encapsulate fields, they could do a calculation on other fields, or serve other purposes.

@GSS points out that you can also do other logic, such as validation, when a property is accessed, another useful feature.

C# – CS0120: An object reference is required for the nonstatic field, method, or property ‘foo’

It looks like you are calling a non static member (a property or method, specifically setTextboxText) from a static method (specifically SumData). You will need to either:

Make the called member static also:

static void setTextboxText(int result)
{
    // Write static logic for setTextboxText.  
    // This may require a static singleton instance of Form1.
}

Create an instance of Form1 within the calling method:

private static void SumData(object state)
{
    int result = 0;
    //int[] icount = (int[])state;
    int icount = (int)state;

    for (int i = icount; i > 0; i--)
    {
        result += i;
        System.Threading.Thread.Sleep(1000);
    }
    Form1 frm1 = new Form1();
    frm1.setTextboxText(result);
}

Passing in an instance of Form1 would be an option also.

Make the calling method a non-static instance method (of Form1):

private void SumData(object state)
{
    int result = 0;
    //int[] icount = (int[])state;
    int icount = (int)state;

    for (int i = icount; i > 0; i--)
    {
        result += i;
        System.Threading.Thread.Sleep(1000);
    }
    setTextboxText(result);
}

More info about this error can be found on MSDN.

Best Answer

Related Solutions

C# – the difference between a field and a property

C# – CS0120: An object reference is required for the nonstatic field, method, or property ‘foo’

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