Passing constructor arguments when using StructureMap

45
votes

I'm using StructureMap for my DI. Imagine I have a class that takes 1 argument like:

public class ProductProvider : IProductProvider
{
     public ProductProvider(string connectionString)
     { 
         ....
     }
}

I need to specify the "connectionString at run-time when I get an instance of IProductProvider.

I have configured StructureMap as follows: 

ForRequestedType<IProductProvider>.TheDefault.Is.OfConcreteType<ProductProvider>().  
WithCtorArgument("connectionString");

However, I don't want to call EqualTo("something...") method here as I need some facility to dynamically specify this value at run-time.

My question is: how can I get an instance of IProductProvider by using ObjectFactory?

Currently, I have something like:

ObjectFactory.GetInstance<IProductProvider>();

But as you know, this doesn't work...

Any advice would be greatly appreciated.

3
dependency-injectionconstructorstructuremap

3 Answers

59
votes

I suggest declaring that with the StructureMap configuration. Using the slightly newer StructureMap code:

For<IProductProvider>().Use<ProductProvider>
  .Ctor<string>("connectionString").Is(someValueAtRunTime);

This way you don't burden your client code from having to know the value and can keep your IoC configuration separate from your main code.

35
votes

I found the answer myself! Here is the solution:

ObjectFactory.With("connectionString").EqualTo(someValueAtRunTime).GetInstance<IProductProvider>();

Hope this helps others who have come across the same issue.

0
votes

If you are running structuremap 2.6.x you will have to do the following:

For<IProductProvider>().Use<ProductProvider>().WithProperty("name").EqualTo(someValueAtRunTime);

Ensure the property name matches the constructor argument.

If your parameter is coming from the app settings use the following line:

.WithProperty("").EqualToAppSetting("")