子活动的自定义活动设置参数

Question

我正在尝试为 WF4 创建一个自定义活动，该活动托管子活动并将一些参数传递给其子活动。我在下面附上了我的活动的简化版本（父活动和子活动），

public class Child : CodeActivity
{
    public InArgument<Dictionary<string, object>> Data;

    protected override void Execute(CodeActivityContext context)
    {
        Dictionary<string, object> data = Data.Get(context);

        //Some operations on the input data
    }
}


 public class Parent : NativeActivity
{
    public InArgument<int> Value1 { get; set; }

    public InArgument<string> Value2 { get; set; }

    public Child Body { get; set; }


    protected override void Execute(NativeActivityContext context)
    {
        int value1 = Value1.Get(context);
        string value2 = Value2.Get(context);

        Dictionary<string, object> data = new Dictionary<string, object>();
        data.Add("value1", value1);
        data.Add("value2", value2);

        context.SetValue(Body.Data, data);

        context.ScheduleActivity(this.Body);
    }


    protected override void CacheMetadata(NativeActivityMetadata metadata)
    {
        Body = new Child();

        base.CacheMetadata(metadata);
    }
}

当工作流执行到达活动的 Execute 方法时，子活动的 Data 参数为 null。

有人可以给我一些指导，如何在这两项活动之间传递争论吗？

Answer 1

虽然使用额外变量的方法有效，但在 ActivityAcytion 中使用调度具有某些输入的子级的“官方”方法，或者如果您还希望使用 ActivityFunc 获得结果。

恐怕代码并没有真正变得更简单或更容易理解，但为了完整性，我决定添加这个。

public class Child : CodeActivity<object>
{
    public InArgument<Dictionary<string, object>> Data { get; set; }

    protected override object Execute(CodeActivityContext context)
    {
        Dictionary<string, object> data = Data.Get(context);

        foreach (var item in data)
        {
            Console.WriteLine(item);
        }

        return "Some result";
    }
}



public class Parent : NativeActivity<object>
{
    public InArgument<int> Value1 { get; set; }
    public InArgument<string> Value2 { get; set; }

    public ActivityFunc<Dictionary<string, object>, object> Body { get; set; }

    protected override void Execute(NativeActivityContext context)
    {
        int value1 = Value1.Get(context);
        string value2 = Value2.Get(context);

        Dictionary<string, object> data = new Dictionary<string, object>();
        data.Add("value1", value1);
        data.Add("value2", value2);

        context.ScheduleFunc<Dictionary<string, object>, object>(Body, data, ChildCompletionCallback);
    }


    protected override void CacheMetadata(NativeActivityMetadata metadata)
    {
        var arg = new DelegateInArgument<Dictionary<string, object>>();

        Body = new ActivityFunc<Dictionary<string, object>, object>
        {
            Argument = arg,
            Handler = new Child() { Data = arg }
        };

        base.CacheMetadata(metadata);
    }

    private void ChildCompletionCallback(NativeActivityContext context, ActivityInstance completedInstance, object result)
    {
        //Set the output for the parent activity at the completion of the child activity
        this.Result.Set(context, result);
    }
}

Answer 2

我还需要通过父活动返回子活动的结果。为此，我使用了 ScheduleActivity 方法和 CompletionCallback 参数。我在下面附上了包含 out 参数集的父/子示例活动，也许某个时候有人会需要它:)

父：

public class Parent : NativeActivity<object>
{
    public InArgument<int> Value1 { get; set; }
    public InArgument<string> Value2 { get; set; }
    private Variable<Dictionary<string, object>> SomeVariable { get; set; } // intermediate variable

    private Child Body { get; set; }

    public Parent()
    {
        this.SomeVariable = new Variable<Dictionary<string, object>>("SomeVariable");

        this.Body = new Child();
        this.Body.Data = new InArgument<Dictionary<string, object>>(SomeVariable);
    }

    protected override void Execute(NativeActivityContext context)
    {
        int value1 = Value1.Get(context);
        string value2 = Value2.Get(context);

        Dictionary<string, object> data = new Dictionary<string, object>();
        data.Add("value1", value1);
        data.Add("value2", value2);

        this.SomeVariable.Set(context, data);

        context.ScheduleActivity(this.Body, ChildCompletionCallback);
    }

    protected override void CacheMetadata(NativeActivityMetadata metadata)
    {
        base.CacheMetadata(metadata);

        // needs to be cached as implementation child and variable (Body and SomeVariable must be declared as private then)
        metadata.AddImplementationChild(this.Body);
        metadata.AddImplementationVariable(SomeVariable);
    }

    private void ChildCompletionCallback<TResult>(NativeActivityContext context, ActivityInstance completedInstance, TResult result)
    {
        //Set the output for the parent activity at the completion of the child activity
        this.Result.Set(context, result);
    }
}

子：

public class Child : CodeActivity<object>
{
    public InArgument<Dictionary<string, object>> Data { get; set; }

    protected override object Execute(CodeActivityContext context)
    {
        Dictionary<string, object> data = Data.Get(context);

        return "Some result";
    }
}

Answer 3

可能无法直接在 Execute 方法中设置输入参数的值。必须引入一个中间变量。 Child.Data 参数连接到此变量并在 Parent.Execute 方法中。

家长：

public class Parent : NativeActivity
{
    public InArgument<int> Value1 { get; set; }
    public InArgument<string> Value2 { get; set; }
    private Variable<Dictionary<string, object>> SomeVariable { get; set; } // intermediate variable

    private Child Body { get; set; }

    public Parent()
    {
        this.SomeVariable = new Variable<Dictionary<string, object>>("SomeVariable");

        this.Body = new Child();
        this.Body.Data = new InArgument<Dictionary<string, object>>(SomeVariable);
    }

    protected override void Execute(NativeActivityContext context)
    {
        int value1 = Value1.Get(context);
        string value2 = Value2.Get(context);

        Dictionary<string, object> data = new Dictionary<string, object>();
        data.Add("value1", value1);
        data.Add("value2", value2);

        this.SomeVariable.Set(context, data);

        context.ScheduleActivity(this.Body);
    }

    protected override void CacheMetadata(NativeActivityMetadata metadata)
    {
        base.CacheMetadata(metadata);

        // needs to be cached as implementation child and variable (Body and SomeVariable must be declared as private then)
        metadata.AddImplementationChild(this.Body);
        metadata.AddImplementationVariable(SomeVariable);
    }
}

孩子：

public class Child : CodeActivity
{
    // Must be declared as property.
    public InArgument<Dictionary<string, object>> Data
    {
        get;
        set;
    }

    protected override void Execute(CodeActivityContext context)
    {
        var data = this.Data.Get(context);
    }
}

这不是一个好的解决方案，但我在 WF4 中几乎看不到任何好的东西:)。