My Nintex Custom Action not reading in Workflow Variable in SingleLineInput - sharepoint-2010

Question

I've written a custom workflow action that takes in several values, mostly using the SingleLineInput control.
When I assign literal values, I have no issues, but when I try to assign a Workflow Variable, I don't get the actual value of the variable, I get the literal text - something like {WorkflowVariable:XmlValue} - assuming my variable was names XmlValue.
I'm not sure what I could possibly be doing wrong. Any ideas?
Here's code snippets:
The javascript for retrieving the value from the SingleLineInput
function TPAWriteConfig() {
configXml.selectSingleNode("/NWActionConfig/Parameters/Parameter[#Name='FieldValue']/PrimitiveValue/#Value").text = getRTEValue('<%=fieldValue.ClientID%>');
SaveErrorHandlingSection();
return true;
}
The server control:
<Nintex:ConfigurationProperty ID="ConfigurationProperty3" runat="server" FieldTitle="Field Value" RequiredField="True">
<TemplateControlArea>
<Nintex:SingleLineInput runat="server" id="fieldValue"></Nintex:SingleLineInput>
</TemplateControlArea>
</Nintex:ConfigurationProperty>
From my adapter class:
private const string FieldValueProperty = "FieldValue";
NWActionConfig config = new NWActionConfig(this);
config.Parameters[2] = new ActivityParameter();
config.Parameters[2].Name = FieldValueProperty;
config.Parameters[2].PrimitiveValue = new PrimitiveValue();
config.Parameters[2].PrimitiveValue.Value = string.Empty;
config.Parameters[2].PrimitiveValue.ValueType = SPFieldType.Text.ToString();
From the activity class:
public static DependencyProperty FieldValueProperty = DependencyProperty.Register("FieldValue", typeof (string),
typeof (
WriteOnePdfFieldActivity));
public string FieldValue
{
get { return (string) GetValue(FieldValueProperty); }
set { SetValue(FieldValueProperty, value); }
}

Answer 1

I feel a little silly answering my own question, but for the sake of anyone else having the same issues. Here's how it works:
If you're putting a literal value in the field, just use the value
If you're using any other kind of assignment, do a lookup based on the value.
The code below demonstrates:
var fieldValue = FieldValue.StartsWith("{") ? ctx.AddContextDataToString(FieldValue, true) : FieldValue;
This extract the value from the workflow context. Hope this helps.