What technique do you use to persist state?

Nagy Vilmos

Dang Marc, have you been reading my hard drive again? I have a data class that contains named value pairs and supports String, Integer, Double, Date and Boolean values. These can be read from file in a simple format and used to persist state. The data class is also used for passing between services. It is my general throw around format. I need to work out an article for just this as I have 3-4 more that all use it so the DataSet becomes a pre-requisite article to write. One day...

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Lost User

Nagy Vilmos wrote:

Dang Marc, have you been reading my hard drive again?

How is he going to be able to do that? The powere keeps going off and you cannot get a good read on anything.

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Marco Bertschi

App option specific stuff locally on the machine of the client. If there is a server everything else goes there into a database. Else I use depending on the amount of data a SQLite DB or XML/CSV files located in the AppData for everything.

cheers Marco Bertschi

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OriginalGriff

A combination of things. For the simple stuff such as UI persistence, I use Application.Config: Save and restore your form size and location[^] For more complex data I try to stick to DB-like data, with SqlCE files or XML if I want human readable. I also have a encryption class which has a file option for more secure data - but the data I serialise to that is normally XML.

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Ennis Ray Lynch Jr

Back when I was a teenager, I thought saving UI State was all the rage but I soon gave it up. The massive amount of code required to store and manage it and make it all perfect just wasn't worth it. Heck, even today, I have a problem when I load firefox at home. You see I have a laptop hooked up to another monitor. However, that monitor is also wired to another machine. When the other machine is on, Windows on the laptop works fine but when I open something that was previously opened on the second monitor guess where it opens? If Windows and Firefox can't manage to get UI saving settings right why even bother? Plus, if you make an infinitely configurable UI, power users will complain that they can't configure X and that is so obvious or worse an upgrade will wipe their settings and lose you a customer. So, long story short, only save the bare essentials that make the app usable. The rest, don't make configurable unless they ask.

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Marc Clifton

If you are making use of custom files to store config settings, don't call them AppName.config or AppName.exe.config. Oh my. That's good to know! Marc

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Marc Clifton

Ravi Bhavnani wrote:

in a binary serialized Gzip'd file.

Ah, snazzy. :) Marc

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Klaus Werner Konrad

All Settings are stored in the database, and even cascaded: factory (our) settings -> company settings -> user settings

Marc Clifton

Nagy Vilmos wrote:

Dang Marc, have you been reading my hard drive again?

Who, me? :~

Nagy Vilmos wrote:

I need to work out an article for just this

That would be great. The impetus, partly, for my survey'ish question is because I've been adding state/configuration persistence to an app, and I was wondering what sort of "best practices" there might be out there. The .NET class seems not configurable enough - I'd like to leave it open to the developer as to how to persist the state information. On the other hand, it also seems to closely coupled to "the Microsoft way", what with all the binding support, not that one needs to use it. At the moment, I've decided to go for an interface-less, more functional approach, resulting in this raw usage example:

public ApplicationFormController()
{
Program.AppState.Register("Form", () =>
{
return new List()
{
new State("X", View.Location.X),
new State("Y", View.Location.Y),
new State("W", View.Size.Width),
new State("H", View.Size.Height),
new State("WindowState", View.WindowState.ToString()),
};

	},
	state =>
	{
		// Silently handle exceptions for when we add state items that are part of the state file until we 
		// save the state.  This allows me to add new state information without crashing the app on startup.
		Program.Try(() => View.Location = new Point(state.Single(t => t.Key == "X").Value.to\_i(), state.Single(t => t.Key == "Y").Value.to\_i()));
		Program.Try(() => View.Size = new Size(state.Single(t => t.Key == "W").Value.to\_i(), state.Single(t => t.Key == "H").Value.to\_i()));
		Program.Try(() => View.WindowState = state.Single(t => t.Key == "WindowState").Value.ToEnum<FormWindowState>());
	});

}

public override void EndInit()
{
Program.AppState.RestoreState("appState.xml");
}

Marc

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wizardzz

I used to use local xml when I did more UI programming. Database could be nice, but was never a requirement.

Marc Clifton

Klaus-Werner Konrad wrote:

factory (our) settings -> company settings -> user settings

Nice! Marc

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Marc Clifton

Ennis Ray Lynch, Jr. wrote:

If Windows and Firefox can't manage to get UI saving settings right why even bother?

Yes, that's one of the issues I think is important to deal with, as I've often had apps open areas that are no longer visible because I've removed a monitor. Marc

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Forogar

Quote:

// Silently handle exceptions for when we add state items that aren't part of the state file until we

FTFY

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Marc Clifton

Forogar wrote:

FTFY

Why thank you! Correctness in comments is very important! Marc

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Lost User

Marc Clifton wrote:

If you're a .NET developer, do you use ApplicationSettingsBase[^] ?

Yes, get's used from time to time; there's a wizard integrated into the IDE to manipulate the settings-file, it's defaults, and one can very easily bind to a property and forget about it.

Marc Clifton wrote:

if you develop client/server apps, if you store your app's state information locally or in a database so that your user can use any client machine and the UI is configured to their preferences ?

The apps state-information is not stored; only preferences, on user and application-scope (local and global). I've tried to save the complete state once (including undo/redo stack) and have the app restore to that state - it just confuses the users.

Marc Clifton wrote:

And yes, I'm talking about UI things, such as last window size and location

Hence the difference between "local" and "global" user-settings. Some things roam, others don't. The form-size doesn't roam, since my monitors have different sizes at different work-locations.

Marc Clifton wrote:

Same with, say, a tree control - what nodes were expanded and what nodes weren't?

No, not ever. How often do you need to be at that exact place in the tree? If very often, make a shortcut for the user. The reasoning is simlpe; you don't want to wait until the "Windows Explorer" loaded the entire tree, if you can simply click a hyperlink.

Marc Clifton wrote:

Plus things like "exit without asking" info, and so forth.

The question does not even exist. There's only a warning if something is dirty, but I'm not going to ask the user whether he knows what he/she is doing on every action.

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Klaus Werner Konrad

Thanks ! I should add, there is a Y/N field in the table that says 'station specific', so I can use one table for user AND station dependant settings, such as directories.

S Houghtelin

this.WindowState = FormWindowState.Maximized;
this.MinimumSize = this.Size;
this.MaximumSize = this.Size;

Generally I use the an application config file for persistant settings.

It was broke, so I fixed it.

PIEBALDconsult

Users? What are those? I use XML: XmlNode[^]

Marc Clifton

Eddy Vluggen wrote:

you don't want to wait until the "Windows Explorer" loaded the entire tree,

I meant trees like, "to do" lists or some other hierarchical information.

Eddy Vluggen wrote:

on user and application-scope (local and global)

That makes sense. Marc

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RaviBee

IMHO, this is a generic problem: i.e. restoring potentially invalid state. Whenever I restore state (almost always from an editable XML file), my code validates and auto-corrects the data being read. Other examples of this are selecting a tree node that may no longer exist, etc. The bottom line is, it's the developer's responsibility to handle all possible use cases. All this takes additional work and time. And your users will love you for it. /ravi

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