Thread: Writing to web.config

I have added a key/value to AppSettings to hold an integer value that will increment when a function is called. In my global.asaxon application start I want to call a function to populate my appsetting key with an initial value.

When I try loading the app I'm getting an access denied error on a .tmp file.

The code that's called from my Global.asax is as follows:-

Code:

        public static void GetEvalNo()
        {
            Configuration config = WebConfigurationManager.OpenWebConfiguration("~/");
            //config.AppSettings.Settings["EvalNo"].Value = "Got Here";
            //config.Save(ConfigurationSaveMode.Modified);
            //return;
            //KeyValueConfigurationElement appValue = config.AppSettings.Settings["EvalNo"];
            int evalNo = GlobalDAL.GetEvalNo();
            try
            {
                config.AppSettings.Settings["EvalNo"].Value = evalNo++.ToString();
                config.Save(ConfigurationSaveMode.Modified);
                //return evalNo++.ToString();
            }
            catch (Exception ex)
            {
                //appValue.Value = ex.ToString();
            }
        }

My web.config is like this:-

Code:

  <appSettings>
    <add key="EvalNo" value="" />
  </appSettings>

I thought it should be possible to update this value. Any ideas?

OK. IIS_User only had Read & Execute permission on the folder.

Hmm...I'm having another problem.

Each time I refresh the page, it's resetting the value in my web.config.

I'm calling the function in Application_Start of Global.asax. Why is the value getting reset each time I refresh the page? Surely it should only call this when the app is compiled?

Because, every time you're writing to the web.config file, the application recompiles and everything is reset. The web.config file is best used for "set and forget" values.

Ahhh...That would make sense...

Where's the best place to store an incremental application level value?

Basically I have a product table that users allocate an integer value to (there is also a PK integer field) and I have a web service to retrieve the next available value and drop it into the textbox control.

But, if two people access the form at the same time, I want the second person to get the next available value from the application variable, not from the database value.

Does that make sense?

Is it easier to just store in a db field and get the value to reset on application start?

Well, you could create an small XML file akin to the web.config. This file could then be updated as you have envisioned above.

You could have the value stored in a db field, as you indicated, but then you have the problem of updating the value in the database so as to get the next available value when the application restarts.

If having 'holes' in the values doesn't bother you, you could create a db table with an auto increment field and just get the next available value each time. If the user abandons the transaction tho -- that value would not be used.

Have you considered using a guid rather then an integer value.

Yeah I did think about a seperate XML file. I just thought if I'm going to do that, I may aswell just store it in a db.

It's kind of a legacy system. They number each potential product that will be produced and I wanted a simple method to ensure duplicate entries weren't made, but allowing the user to enter a value at the same time. Gaps are not a major problem, just didn't want huge gaps to appear.

I think it'll be slightly redundant, I just want to avoid the possibility of duplicate entries being made. Problem being ensuring no duplicate entries on a user defined field, but also ensuring users who open the page whilst another user is still entering details can not get duplicate.

If that makes any sense...