The following is a simple example of an enum which defines the state of an object and a class which shows the implementation of this enum.
public enum StatusEnum
{
Clean = 0,
Dirty = 1,
New = 2,
Deleted = 3,
Purged = 4
}
public class Example_Class
{
private StatusEnum _Status = StatusEnum.New;
private long _ID;
private string _Name;
public StatusEnum Status
{
get { return _Status; }
set { _Status = value; }
}
public long ID
{
get { return _ID; }
set { _ID = value; }
}
public string Name
{
get { return _Name; }
set { _Name = value; }
}
}
when populating the class object with data from the database, we set the enum value to "clean". with the goal of keeping most of the logic out of the presentation layer, how can we set the enum value to "dirty" when a property is changed.
i was thinking something along the lines of;
public string Name
{
get { return _Name; }
set
{
if (value != _Name)
{
_Name = value;
_Status = StatusEnum.Dirty;
}
}
}
in the setter of each property of the class.
does this sound like a good idea, does anyone have any better ideas on how the dirty flag can be assigned without doing so in the presentation layer.
This method is based on a set of different concepts provided in this thread. I thought i'd put it out there for anyone that is looking for a way to do this cleanly and efficiently, as i was myself.
The key of this hybrid concept is that:
Given those requirements, this is what i came up with, and it seems to be working perfectly for me, and has become very useful when working against UIs and capturing user changes accurately. I have also posted an "How to use" below to show you how I use this in the UI.
The Object
It's simple enough and addresses all of our requirements:
Of course you can adapt this to encompass a bunch of different states... it's really up to you. This example only shows how to have a proper IsDirty flag operation.
Scenarios
Let's go over some scenarios for this and see what comes back:
Scenario 1
New object is created using empty constructor,
Property Name changes from "" to "James",
call to IsDirty returns True! Accurate.
Scenario 2
New object is created using paramters of "John" and 12345,
Property Name changes from "John" to "James",
Property Name changes back from "James" to "John",
Call to IsDirty returns False. Accurate, and we didn't have to duplicate the data to do it either!
How to use, a WinForms UI example
This is only an example, you can use this in many different ways from a UI.
Let's say you have a two forms ([A] and [B]).
The first([A]) is your main form, and the second([B]) is a form that allows the user to change the values within the MySmartObject.
Both the [A] and the [B] form have the following property declared:
When the user clicks a button on the [A] form, an instance of the [B] form is created, its property is set and it is displayed as a dialog.
After form [B] returns, the [A] form updates its property based on the [B] form's IsDirty check. Like this:
Also, in [B], when it is closing, you can check and prompt the user if they are closing the form with unsaved changes in it, like so:
As you can see from the examples above, this can be a very useful thing to have since it really streamlines the UI.
Caveats
Hopefully this helps someone.