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I'm building a project that includes an MVC Web Api hosted in Azure and an iOS app. I'm trying to use Xamarin to build the app. As I understand it, I should use a portable class library in my Xamarin project to allow me to share the code between my Web Api project and the Xamarin app, as well as any future apps on other platforms like android.

So right off the bat I would want to put my models in the portable library. The app and the web api will pass those models back and forth. But the portable library doesn't have the Azure Table Storage library. It doesn't even have some very basic stuff. My models need to reference the Azure Storage Library so I can save instances to storage.

What is the best way to make this code shareable? Obviously I need to duplicate my model classes so they can exist in each location. But should those in the PCL inherit from those in the Web Api project? Vice versa? Should there be an interface that both inherit from (actually the Azure Table Storage library requires the classes to inherit from ITableEntity already...). Just looking for the best way to share these classes between the Web Api project and the PCL used by the Xamarin project.

Andrew B Schultz
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1 Answers1

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Using a PCL - Portable Class Library is a great way to get started! There are a few quirks that you may want to understand prior to sharing your code.

  • The PCL Profile is a limited set of APIs available. Meaning that certain classes/assemblies might not be included. You can typically look up the class/assembly via MSDN and see if it has a PCL icon next to the class name.

  • If the library you are trying to use has assemblies not inside the current PCL Profile but can be found on the native platforms, you will want to use the IoC/DI pattern.

  • Hopefully the library you're using supports PCL. Otherwise, you will need a library that does support the PCL Profile. (You can check this by downloading the .nupkg, extracting, and looking at the libs folder). Note: You may want to check the Prerelease NuGet channel for PCL support. Sometimes you can find an open source project and remove/replace certain assemblies/code to make it Portable.

General Guidelines:

  • Keep your POCO classes simple in the PCL. If you have platform specific quirks you need to add to the models, make a Model layer on that platform that inherits from your simple PCL models. EX: Your Web API has a specific [Attribute] tag or interface that you need to apply to your model. You might already have a Model such as Person which is a simple POCO class in your PCL, and then you can create a PersonApiEntity model which might inherit Person and any platform-specific APIs you need to apply to it.

  • It seems ITableEntity/TableEntity is not supported in the PCL Profile.

https://msdn.microsoft.com/en-us/library/microsoft.windowsazure.storage.table.itableentity.aspx

Seeing the source at a quick glance(https://github.com/Azure/azure-storage-net/blob/master/Lib/Common/Table/ITableEntity.cs)

Jon Douglas
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  • Thanks Jon! That's what I needed to know. I'll put POCOs in the PCL and inherit from them in the Web API project. – Andrew B Schultz Mar 31 '16 at 00:01
  • Jon, one little snag - my classes in the Web API project need to inherit from Microsoft.WindowsAzure.Storage.Table.TableEntity. Which means they cannot also inherit from my POCOs in the PCL. What is the best approach in a situation like this - would you create a set of intermediary classes that inherit from the POCOs, and then derive your Web API classes from those intermediary classes? That seems messy, but I don't have any better ideas... – Andrew B Schultz Apr 02 '16 at 13:19
  • Looks like the answer from @MikeWo here http://stackoverflow.com/questions/33912186/using-pocos-when-persisting-to-azure-table-storage has some good options in the links from Rory Primrose, although they may be a bit beyond my current skill level. Seems like you can inherit from POCOs and implement ITableEntity and get away with that as well, although it's not ideal. – Andrew B Schultz Apr 02 '16 at 13:49