Collections in XAML

Question

Hi,

Is there a sample somewhere describing how to use collections in XAML?  The collections app in the Beta 1 samples is purely code based.  I'm just declaring a collections variable in a sequence activity and then dragging an AddToCollection activity into that sequence.  The IDE lets me bind the AddToCollection.Collection property to my sequence variable, but complains at runtime: System.InvalidOperationException: The property 'Collection' of 'AddToCollection`1' must be set.

My XAML is below if it helps.  Thanks very much,

- Erik

<p:Activity mc:Ignorable="" x:Class="WorkflowConsoleApplication1.Sequence1" xmlns="http://schemas.microsoft.com/netfx/2009/xaml/activities/design" xmlns:__Sequence1="clr-namespace:WorkflowConsoleApplication1;" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:p="http://schemas.microsoft.com/netfx/2009/xaml/activities" xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:sad="clr-namespace:System.Activities.Debugger;assembly=System.Activities" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

  <p:Sequence DisplayName="MySequence" sad:XamlDebuggerXmlReader.FileName="C:\Users\ejohnson\Documents\Visual Studio 10\Projects\TestAct\WorkflowConsoleApplication1\Sequence1.xaml">

    <p:Sequence.Variables>

      <p:Variable x:TypeArguments="s:Int32[]" Name="DataIn" />

    </p:Sequence.Variables>

    <p:AddToCollection x:TypeArguments="x:Int32" Item="[42]">[DataIn]</p:AddToCollection>

  </p:Sequence>

</p:Activity>

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Erik Johnson

Answer 1

Thanks for reporting the issue.
Seems like a bug. Let me double check and get back to you.
Kavita

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Senior Lead Program Manager, Windows Workflow Foundation http://blogs.msdn.com/kavitak

Answer 2

No, actually the problem is this -
your variable isnt initialized. If you do, you'll get an error saying the array is of a fixed type.

Try: List<int>

<p:Activity mc:Ignorable="" x:Class="WorkflowConsoleApplication2.Sequence1" xmlns="http://schemas.microsoft.com/netfx/2009/xaml/activities/design" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:p="http://schemas.microsoft.com/netfx/2009/xaml/activities" xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:sad="clr-namespace:System.Activities.Debugger;assembly=System.Activities" xmlns:scg="clr-namespace:System.Collections.Generic;assembly=mscorlib" xmlns:w="clr-namespace:WorkflowConsoleApplication2;assembly=WorkflowConsoleApplication2" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

  <p:Sequence sad:XamlDebuggerXmlReader.FileName="C:\Users\kavitak\SharedwDesktop\Work\Beta1\Scratch\WorkflowConsoleApplication2\WorkflowConsoleApplication2\Sequence1.xaml">

    <p:Sequence.Variables>

      <p:Variable x:TypeArguments="x:Int32" Default="[2]" Name="test" />

      <p:Variable x:TypeArguments="scg:IList(x:Int32)" Default="[New List(Of Int32)]" Name="numbers" />

    </p:Sequence.Variables>

    <p:WriteLine>[test.ToString()]</p:WriteLine>

    <p:AddToCollection x:TypeArguments="x:Int32" Item="[12]">[numbers]</p:AddToCollection>

    <p:ForEach Values="[numbers]">

      <p:ActivityAction x:TypeArguments="s:Object">

        <p:ActivityAction.Argument>

          <p:Variable x:TypeArguments="s:Object" Name="item" />

        </p:ActivityAction.Argument>

        <p:WriteLine>[item.ToString()]</p:WriteLine>

      </p:ActivityAction>

    </p:ForEach>

  </p:Sequence>

</p:Activity>

 

 

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Senior Lead Program Manager, Windows Workflow Foundation http://blogs.msdn.com/kavitak

Answer 3

we'll make the error message clearer in beta2.

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Senior Lead Program Manager, Windows Workflow Foundation http://blogs.msdn.com/kavitak

Answer 4

Thanks Kavita.  I knew if I saw a working example, it would clear things up. 

The IDE is a little unhelpful because it shows a fixed-size array of T in the initial drop-down.  I wasn't sure if writing oput the fully-qualified name of List<> was the right thing to do. I'm sure that's going to get tuned up over time.

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Erik Johnson