DefaultValue on WebPart Custom Properties

Question

I'm new to SharePoint and I'm developing a WebPart.

I'm trying to create some properties with a DefaultValue, but they stay null.

Here is how I'm defining my property in my class:

public static string titleWP;
[Category("Extended Settings"),
Personalizable(PersonalizationScope.Shared),
WebBrowsable(true),
DefaultValue("Résultats de recherche"),
WebDisplayName("Titres de la WebPart"),
WebDescription("Entrez le titre de la WebPart")]
public string _titleWP
{
    get { return titleWP; }
    set { titleWP = value; }
}

And in CreateChildControls, if I do this, I get an exception because titleWP is null

if (string.IsNullOrEmpty(titleWP.Trim()))
{
    titleWP = "search result";
}

How can I fix this?

Edit:

Strange thing is if I do an IISRESET or update-spsolution(because make changes) the value that the users enter disappears and it retrieves the default value.

What is the best practice for defining a property and don't lose what the user modify?

Answer 1

Do not store titleWP property as static (I think this is the reason why IISReset clears the value)

I would use something like this:

private const string DefaultTitleWP = "Résultats de recherche";
private string _titleWP = DefaultTitleWP;
[Category("Extended Settings"),
Personalizable(PersonalizationScope.Shared),
WebBrowsable(true),
DefaultValue(DefaultTitleWP)
WebDisplayName("Titres de la WebPart"),
WebDescription("Entrez le titre de la WebPart")]
public string TitleWP
{
    get { return _titleWP; }
    set { _titleWP = value; }
}

Answer 2

I don't think DefaultValue works very well.

Try this:

titleWP = titleWP ?? "Résultats de recherche";
if (string.IsNullOrEmpty(titleWP.Trim()))
{
    titleWP = "search result";
 }

Answer 3

Why not use

string.IsNullOrWhiteSpace(titleWP)

This will check null, empty or just white space (like row breaks and blanks)