Where should I create my DbCommand instances?
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by Domenic
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Published on 2009-08-09T19:33:34Z
Indexed on
2010/04/25
18:33 UTC
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I seemingly have two choices:
- Make my class implement
IDisposable
. Create myDbCommand
instances asprivate readonly
fields, and in the constructor, add the parameters that they use. Whenever I want to write to the database, bind to these parameters (reusing the same command instances), set theConnection
andTransaction
properties, then callExecuteNonQuery
. In theDispose
method, callDispose
on each of these fields. - Each time I want to write to the database, write
using(var cmd = new DbCommand("...", connection, transaction))
around the usage of the command, and add parameters and bind to them every time as well, before callingExecuteNonQuery
. I assume I don't need a new command for each query, just a new command for each time I open the database (right?).
Both of these seem somewhat inelegant and possibly incorrect.
For #1, it is annoying for my users that I this class is now IDisposable
just because I have used a few DbCommand
s (which should be an implementation detail that they don't care about). I also am somewhat suspicious that keeping a DbCommand
instance around might inadvertently lock the database or something?
For #2, it feels like I'm doing a lot of work (in terms of .NET objects) each time I want to write to the database, especially with the parameter-adding. It seems like I create the same object every time, which just feels like bad practice.
For reference, here is my current code, using #1:
using System;
using System.Net;
using System.Data.SQLite;
public class Class1 : IDisposable
{
private readonly SQLiteCommand updateCookie = new SQLiteCommand("UPDATE moz_cookies SET value = @value, expiry = @expiry, isSecure = @isSecure, isHttpOnly = @isHttpOnly WHERE name = @name AND host = @host AND path = @path");
public Class1()
{
this.updateCookie.Parameters.AddRange(new[]
{
new SQLiteParameter("@name"),
new SQLiteParameter("@value"),
new SQLiteParameter("@host"),
new SQLiteParameter("@path"),
new SQLiteParameter("@expiry"),
new SQLiteParameter("@isSecure"),
new SQLiteParameter("@isHttpOnly")
});
}
private static void BindDbCommandToMozillaCookie(DbCommand command, Cookie cookie)
{
long expiresSeconds = (long)cookie.Expires.TotalSeconds;
command.Parameters["@name"].Value = cookie.Name;
command.Parameters["@value"].Value = cookie.Value;
command.Parameters["@host"].Value = cookie.Domain;
command.Parameters["@path"].Value = cookie.Path;
command.Parameters["@expiry"].Value = expiresSeconds;
command.Parameters["@isSecure"].Value = cookie.Secure;
command.Parameters["@isHttpOnly"].Value = cookie.HttpOnly;
}
public void WriteCurrentCookiesToMozillaBasedBrowserSqlite(string databaseFilename)
{
using (SQLiteConnection connection = new SQLiteConnection("Data Source=" + databaseFilename))
{
connection.Open();
using (SQLiteTransaction transaction = connection.BeginTransaction())
{
this.updateCookie.Connection = connection;
this.updateCookie.Transaction = transaction;
foreach (Cookie cookie in SomeOtherClass.GetCookieArray())
{
Class1.BindDbCommandToMozillaCookie(this.updateCookie, cookie);
this.updateCookie.ExecuteNonQuery();
}
transaction.Commit();
}
}
}
#region IDisposable implementation
protected virtual void Dispose(bool disposing)
{
if (!this.disposed && disposing)
{
this.updateCookie.Dispose();
}
this.disposed = true;
}
public void Dispose()
{
this.Dispose(true);
GC.SuppressFinalize(this);
}
~Class1()
{
this.Dispose(false);
}
private bool disposed;
#endregion
}
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