Passing constructor arguments when using StructureMap

Question

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.

Jaxidian · Accepted Answer · 2013-05-10 07:13:10Z

63

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.

edited May 10, 2013 at 7:13

Jaxidian

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answered May 20, 2010 at 18:49

Michael Hedgpeth

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1 Comment

user1713059 Over a year ago

I'm guessing this is the place were you configure StructureMap. How do You pass the someValueAtRunTime there?

Mosh · Accepted Answer · 2010-05-13 02:38:55Z

36

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.

answered May 13, 2010 at 2:38

Mosh

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3 Comments

Mel Over a year ago

Make sure that someValueAtRuntime is a simple value, not any kind of Func or Lambda (if you can do that) for retrieving it, otherwise that function will run every time the dependency is resolved. I used this trick to inject a connection string, just as you're doing. As long as you get the string into a local variable before setting up ObjectFactory, you should be fine.

J0NNY ZER0 Over a year ago

Yo. What if I have several arguments, arg1, 2, 3 etc. And I want to pass in every argument as is but keep one of the args as null. How to do this?

wandos Over a year ago

@Mosh thank you for the answer, how ever can you please tell me how are you passing someValueAtRuneTime? an example of it please.

JWallace · Accepted Answer · 2019-12-19 13:16:20Z

0

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("")

answered Dec 19, 2019 at 13:16

JWallace

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