There is no argument given that corresponds to the

问题:

I have been re-factoring one of my old MSSQL Connection helper library and I got the following error:

Severity Code Description Project File Line Error CS7036 There is no argument given that corresponds to the required formal parameter 'errorMsg' of 'ErrorEventArg.ErrorEventArg(string, string)' MSSQLTest C:\Users\Administrator\Desktop\MSSQLTest\MSSQLTest\MSSQLConnection.cs 61

This is my code so far:

MSSQLConnection.cs

using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Threading;

namespace MSSQLTest
{
    public class ErrorEventArg : EventArgs
    {
        public string ErrorMsg { get; set; }
        public string LastQuery { get; set; }

        public ErrorEventArg(string errorMsg, string lastQuery)
        {
            ErrorMsg = errorMsg;
            LastQuery = lastQuery;
        }
    }

    public class MSSQLConnection
    {
        /// <summary>
        /// Private class objects.
        /// </summary>
        private SqlConnection sqlConnection;
        private int sqlCommandTimeout;
        private string lastQuery = string.Empty;

        /// <summary>
        /// Public event related objects & handler.
        /// </summary>
        public event ErrorHandler OnError;
        public delegate void ErrorHandler(MSSQLConnection sender, ErrorEventArg e);

        /// <summary>
        /// Class constructor.
        /// </summary>
        /// <param name="sqlConnection"></param>
        /// <param name="sqlCommandTimeout"></param>
        public MSSQLConnection(SqlConnection sqlConnection, Int32 sqlCommandTimeout = 120)
        {
            if (null == sqlConnection)
                throw new Exception("Invalid MSSQL Database Conection Handle");

            if (sqlConnection.State != System.Data.ConnectionState.Open)
                throw new Exception("MSSQL Database Connection Is Not Open");

            this.sqlConnection = sqlConnection;
            this.sqlCommandTimeout = sqlCommandTimeout;
        }

        /// <summary>
        /// Helper method to emit a database error to event subscribers.
        /// </summary>
        /// <param name="errorMsg"></param>
        internal void EmitError(String errorMsg)
        {
            var errorDelegate = OnError;
            if (errorDelegate != null)
            {
                errorDelegate(this, new ErrorEventArg() // Line #61
                {
                    ErrorMsg = errorMsg,
                    LastQuery = lastQuery
                });
            }
        }

        /// rest of the code snipped
    }
}

What does this error means & how do I fix it? I've not seen this error before...

回答1:

You have a constructor which takes 2 parameters. You should write something like:

new ErrorEventArg(errorMsv, lastQuery)

It's less code and easier to read.

EDIT

Or, in order for your way to work, you can try writing a default constructor for ErrorEventArg which would have no parameters, like this:

public ErrorEventArg() {}

回答2:

In the constructor of

 public class ErrorEventArg : EventArgs

You have to add "base" as follows:

    public ErrorEventArg(string errorMsg, string lastQuery) : base (string errorMsg, string lastQuery)
    {
        ErrorMsg = errorMsg;
        LastQuery = lastQuery;
    }

That solved it for me

回答3:

I got the same error but it was due to me not creating a default constructor. If you haven't already tried that, create the default constructor like this:

public TestClass() {

}

回答4:

I got this error when one of my properties that was required for the constructor was not public. Make sure all the parameters in the constructor go to properties that are public if this is the case:

using statements namespace someNamespace

public class ExampleClass {

  //Properties - one is not visible to the class calling the constructor
  public string Property1 { get; set; }
  string Property2 { get; set; }

   //Constructor
   public ExampleClass(string property1, string property2)
  {
     this.Property1 = property1;
     this.Property2 = property2;  //this caused that error for me
  }
}