Constructor chaining and static property parameter and StructureMap

Question

I would like my constructor to call another constructor with parameter but when I do this(MyProperty), then MyProperty must be static. And the problem is in the getter of this static Property, I have to get an instance of ISettingReader from structuremap Container and as it is static, my container contains only two elements instead of more than 50 elements, then it can't find the instance. (Error of pluginFamily on ISettingReader)

Here's my code.

    private static Func<LinqDataContext> _contextFactory;
    public static Func<LinqDataContext> DefaultContextFactory
    {
        get
        {
            var settingReader = ObjectFactory.GetInstance<ISettingReader>(); // I get an error saying it can't find ISettingReader()
            var connectionString = settingReader.GetSetting("MyProject.ConnectionString");
            _contextFactory = () => new LinqDataContext(connectionString);
            return _contextFactory;
        }
    }

    public MyProjectViewModelService() : this(DefaultContextFactory)
    {

    }

    public MyProjectViewModelService(Func<LinqDataContext> contextFactory)
    {
        _contextFactory = contextFactory;
    }

I think if I can get rid of my static keyword, it should work. And I confirm I have initialized my ISettingReader in structureMap container when I started my application in Program.exe

So what should I do ? Thanks !

John

PS: there's similar problem I found on stackoverflow, but he doesn't use structureMap: Constructor chaining with intermediate variables

thekip · Accepted Answer · 2011-06-06 10:18:08Z

1

Why don't you move the code from your getter to the default constructor and put the ISettingReader as a dependency in the constructor. When you request a new MyProjectViewModelService Structuremap will automatically resolve the ISettingReader and supply the instantiated default type for that dependency.

So if you would have
public MyProjectViewModelService(ISettingReader settingReader) { var connectionString = settingReader.GetSetting("MyProject.ConnectionString"); _contextFactory = () => new LinqDataContext(connectionString); }

You can remove the rest.

The exception you get from structuremap is because you didn't configure any default instance for ISettingReader

answered Jun 6, 2011 at 10:18

thekip

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1 Comment

John Over a year ago

you are absolutely right. I thought I know well structuremap but actually not -_-. But thanks a lot anyway thekip, you're the god of C# development.

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