Lookup Activities in Visual Studio 2012

When you develop a workflow in VS 2012 you probably want to work with other lists of your SPWeb, not only the current list either the task list. But you may get this error:

 System.FormatException: Expected hex 0x in "{0}".   

Problem is that substitution "$ListId:Lists/MyList" doesn't work in flow scope.


Solution:


For the Task list of your current workflow you can use the GetTaskListId activity from "SP - Current Context" group and save task_list_id to the GUID variable. But if you want to get data from other lists of the web (for example to get data from lookup fields and other lists), issue gets more complicated. Here is a solution.
Add a property to the Elements.xml file of your Workflow like this:

 

 <File Url="Workflow.xaml" Type="GhostableInLibrary" Path="ContractorSecurityCheckWorkflow\Workflow.xaml" DoGUIDFixUp="TRUE">  
    ...  
    <Property Name="MyListId" Value="{$ListId:Lists/MyList;}" />  
 </File>  
 <File Url="WorkflowStartAssociation" Path="Workflow\WorkflowStartAssociation" Type="GhostableInLibrary">  
    ...  
    <Property Name="MyListId" Value="{$ListId:Lists/MyList;}" />  
 </File>  

and use GetConfigurationValue activity from Runtime group to save MyListId property to the string variable list_id. Then just use System.Guid.Parse(list_id).