工作流基础4-即使Execute方法显示为true,ActivityFunc<bool>的结果始终为false

你好,有人谁我从来没有见过,只是碰巧分享我的IP。

要么你正在使用的活动的DLL不是最新的,要么工作流定义已经过时,不能保存你认为它所做的事情。或者完全不同。

我已经精简了你的代码并将其压缩成一个示例项目。我们想在这里看到它:

public sealed class AnTrigger : NativeActivity<bool>
{
    public bool ResultToSet { get; set; }

    protected override void Execute(NativeActivityContext context)
    {
        Result.Set(context, ResultToSet);
    }
}

很简单,不是吗?这是计算此条件的主机,如果返回true,则运行单个子活动。注意,我正在Create方法中构造活动,因此不必创建编辑器。

public sealed class AnTriggerHost : NativeActivity, IActivityTemplateFactory
{
    public ActivityFunc<bool> Condition { get; set; }
    public ActivityAction Child { get; set; }

    protected override void Execute(NativeActivityContext context)
    {
        context.ScheduleFunc(Condition, OnConditionComplete);
    }

    private void OnConditionComplete(
        NativeActivityContext context, 
        ActivityInstance completedInstance, 
        bool result)
    {
        if (result)
            context.ScheduleAction(Child);
    }

    Activity IActivityTemplateFactory.Create(System.Windows.DependencyObject target)
    {
        // so I don't have to create UI for these, here's a couple samples
        // seq is the first child and will run as the first AnTrigger is configured to return true
        // so the first trigger evals to true and the first child runs, which
        var seq = new Sequence
        {
            DisplayName = "Chief Runs After First Trigger Evals True"
        };
        // prints this message to the console and
        seq.Activities.Add(new WriteLine { Text = "See this?  It worked." });
        // runs this second trigger host, which 
        seq.Activities.Add(
            new AnTriggerHost
            {
                DisplayName = "This is the SECOND host",
                Condition = new ActivityFunc<bool>
                {
                    // will NOT be triggered, so you will never see
                    Handler = new AnTrigger
                    {
                        ResultToSet = false,
                        DisplayName = "I return false guize"
                    }
                },
                Child = new ActivityAction
                {
                    // this activity write to the console.
                    Handler = new WriteLine
                    {
                        Text = "you won't see me"
                    }
                }
            });

        return new AnTriggerHost
        {
            DisplayName = "This is the FIRST host",
            Condition = new ActivityFunc<bool>
            {
                Handler = new AnTrigger
                {
                    ResultToSet = true,
                    DisplayName = "I return true!"
                }
            },
            Child = new ActivityAction
            {
                Handler = seq
            }
        };
    }
}

将这两个放到工作流控制台应用程序中,并将AnTriggerHost放到工作流中。设置几个断点,看着它飞起来。以下是工作流xaml:

  <local:AnTriggerHost DisplayName="This is the FIRST host" >
    <local:AnTriggerHost.Child>
      <ActivityAction>
        <Sequence DisplayName="Chief Runs After First Trigger Evals True">
          <WriteLine Text="See this?  It worked." />
          <local:AnTriggerHost DisplayName="This is the SECOND host">
            <local:AnTriggerHost.Child>
              <ActivityAction>
                <WriteLine Text="you won't see me" />
              </ActivityAction>
            </local:AnTriggerHost.Child>
            <local:AnTriggerHost.Condition>
              <ActivityFunc x:TypeArguments="x:Boolean">
                <local:AnTrigger DisplayName="I return false guize" ResultToSet="False" />
              </ActivityFunc>
            </local:AnTriggerHost.Condition>
          </local:AnTriggerHost>
        </Sequence>
      </ActivityAction>
    </local:AnTriggerHost.Child>
    <local:AnTriggerHost.Condition>
      <ActivityFunc x:TypeArguments="x:Boolean">
        <local:AnTrigger DisplayName="I return true!" ResultToSet="True" />
      </ActivityFunc>
    </local:AnTriggerHost.Condition>
  </local:AnTriggerHost>

供将来参考。。。当这种情况发生在我身上,原因是我 Result 在IActivityTemplateFactory的Create方法中

Activity IActivityTemplateFactory.Create(System.Windows.DependencyObject target)
{
    return new Child
    {
        InputText = new InArgument<string>(
            new VisualBasicValue<string>(Parent.InputTextVariable)),
        // the following demonstrates what NOT to do in the Create method. 
        // this BREAKS your ActivityFunc, which will ALWAYS return default(T)
        // DO NOT SET Result AT ANY TIME OR IN ANY PLACE
        // BEGIN ERROR
        Result = new OutArgument<string>()
        // END ERROR
    };
}

<!--If you see ActivityFunc.Result in your workflow, DELETE IT -->
<ActivityFunc.Result>
  <DelegateOutArgument x:TypeArguments="x:String" />
</ActivityFunc.Result>

ScheduleFunc始终采用ActivityFunc,其中条件定义为ActivityFunc。不确定非泛型ActivityFunc来自何处。CompletionCallback也应该是CompletionCallback。

我使用的测试代码:

IActivityTemplateFactory factory = new Trigger();
var trigger = (Trigger)factory.Create(null);
trigger.Condition.Handler = new AlwaysTrue();
trigger.Child.Handler = new WriteLine()
{
    Text = "Its true."
};
WorkflowInvoker.Invoke(trigger);

class AlwaysTrue : CodeActivity<bool>
{
    protected override bool Execute(CodeActivityContext context)
    {
        return true;
    }
}

Activity IActivityTemplateFactory.Create(System.Windows.DependencyObject target)
{
    return new Trigger()
    {
        Child = new ActivityAction()
        {
            DisplayName = "Trigger Child Action"
        },

        Condition = new ActivityFunc<bool>()
        {
            DisplayName = "Trigger Conditionals"
        },
        DisplayName = "Trigger"
    };
}