How do I store an array of a particular type into my settings file?

Question

For some reason, I can't seem to store an array of my class into the settings. Here's the code:

            var newLink = new Link();
            Properties.Settings.Default.Links = new ArrayList();
            Properties.Settings.Default.Links.Add(newLink);
            Properties.Settings.Default.Save();

In my Settings.Designer.cs I specified the field to be an array list:

    [global::System.Configuration.UserScopedSettingAttribute()]
    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
    public global::System.Collections.ArrayList Links {
        get {
            return ((global::System.Collections.ArrayList)(this["Links"]));
        }
        set {
            this["Links"] = value;
        }
    }

For some reason, it won't save any of the data even though the Link class is serializable and I've tested it.

"I can't seem" How do you see that? Is an exception thrown? Is the list empty when loading? Is is empty without reloading? — Foxfire, May 03 '10 at 23:52
The list is empty with no exceptions thrown. Somehow it isn't serializing my Links. — ATL_DEV, May 03 '10 at 23:54
Is the data contained in the settings file (it's an XML file so you can easily check)? — Foxfire, May 03 '10 at 23:56
I checked the user.config and there are no Links contained in the array. — ATL_DEV, May 03 '10 at 23:59
Here's the user.config file: Interestingly, I tried to write an array of integers and it worked fine. I wonder what gives? — ATL_DEV, May 04 '10 at 00:05

score 3 · Accepted Answer · answered May 05 '10 at 02:42

I found the source of the problem. Simply using a plain Array won't cut it. After thinking about it, the deserializer wouldn't know what type to deserialize the array items to. I failed to see that the array required strong typing. The designer lead me to foolishly believe it was a plain generic array:

    [global::System.Configuration.UserScopedSettingAttribute()]
    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
    public List<Link> Links
    {
        get {
            return ((List<Link>)(this["Links"]));
        }
        set {
            this["Links"] = value;
        }
    }

I had to make these changes in the Settings.Designer.cs and not from the designer.

Thanks, that answer just helped me a out a ton! – Evan Oct 07 '11 at 00:51 — Evan, Oct 07 '11 at 00:51

score 1 · Answer 2 · answered May 04 '10 at 00:26

Make sure that your Link class is either correctly XML-serializable or that it has a typeconverter to string (which is preferred when using application.settings files).

I'd assume that something in your types will not transform into the XML-serialization format. And your user.config shows that it doesn't have any string typeconverter available.

How do I store an array of a particular type into my settings file?

2 Answers2

Linked