Re: Is Dirty

Thanks Dean,  I think I'll look at the hashing method.

> -----Original Message-----
> From: Discussion forum for developers using Windows Forms to build apps
> and controls [mailto:[email protected]] On Behalf Of
> Dean Cleaver
> Sent: 17 May 2007 22:29 PM
> To: [email protected]
> Subject: Re: [DOTNET-WINFORMS] Is Dirty
>
> Brady,
>
> I have done this in two ways:
>
> 1. Internally all data for my class was stored in another class (or
> structure) like this:
>
> public class Person
> {
>     private class PersonData
>     {
>         public string Name;
>         public int Age;
>     }
>
>     private PersonData original
>     private personData current
>
>     public class Person(string name, int age)
>     {
>         this.original = new PersonData()
>         this.original.Name = name;
>         this.original.Age = age;
>
>         this.current = new PersonData()
>         this.current.Name = name;
>         this.current.Age = age;
>     }
>
>     public string Name
>     {
>         get {return this.current.Name;}
>         set {this.current.Name = value;}
>     }
>
>     public int Age
>     {
>         get {return this.current.Age;}
>         set {this.current.Age= value;}
>     }
>
>     public bool IsDirty
>     {
>         get
>         {
>             if (this.current.Name != this.original.name)
>                 return true;
>
>             if (this.current.Name != this.original.name)
>                 return true;
>
>             return false;
>         }
>     }
> }
>
>
> 2. Create a string that is a sum of all properties, and store the MD5
> hash of that string - then at any time, you just need to compare the
> hash to the current hash to see if it's changed.
>
> public class Person
> {
>     private byte[] md5Hash;
>
>     public class Person(string name, int age)
>     {
>         this.name = name;
>         this.age = age;
>
>         StringBuilder builder = new StringBuilder();
>
>         builder.Append(this.name);
>         builder.Append(this.age.ToString());
>
>         this.md5Hash = new
> MD5CryptoServiceProvider().ComputeHash(Encoding.ASCII.GetBytes(builder.T
> oString()));
>     }
>
>     private string name;
>     public string Name
>     {
>         get {return this.name;}
>         set {this.name = value;}
>     }
>
>     private int age;
>     public int Age
>     {
>         get {return this.age;}
>         set {this.age= value;}
>     }
>
>     public bool IsDirty
>     {
>         get
>         {
>             StringBuilder builder = new StringBuilder();
>
>             builder.Append(this.name);
>             builder.Append(this.age.ToString());
>
>             byte[] data = new
> MD5CryptoServiceProvider().ComputeHash(Encoding.ASCII.GetBytes(builder.T
> oString()));
>             return !CompareArrays(data, this.md5Hash);
>         }
>     }
>
>     internal static bool CompareArrays(byte[] byte1, byte[] byte2)
>     {
>         try
>         {
>             if (byte1 == null && byte2 == null)
>                 return true;
>
>             if (byte1 == null || byte2 == null)
>                 return false;
>
>             if (byte1.Length != byte2.Length)
>                 return false;
>
>             for (int i = 0; i < byte1.Length; i++)
>                 if (byte1[i] != byte2[i])
>                      return false;
>
>             return true;
>            }
>         catch
>         {
>             return false;
>         }
>     }
> }
>
>
> The first one has the benefit in that you can tell exactly what changed
> - but I was using remoting, and it meant I was sending double the data
> everywhere, so the second one has the benefit of sending less data over
> the wire.
>
> HTH
> Dino
>
> -----Original Message-----
> From: Discussion forum for developers using Windows Forms to build apps
> and controls [mailto:[email protected]] On Behalf Of
> Brady Kelly
> Sent: Friday, 18 May 2007 02:25
> To: [email protected]
> Subject: [DOTNET-WINFORMS] Is Dirty
>
> I'm doing a quick and dirty prototype app, with one simple detail edit
> screen, so I've used simple own code to transfer values between controls
> and data entity, deferring properly implementing data binding at a later
> stage[1].  Now I want to know if the edited entity is 'dirty'.  My first
> reaction is to serialise it on starting my edit, and then when closing
> the form, and compare the two.  How do the experts here feel about this?