WF4.0论坛Q/A

    偶发现微软的WF4.0论坛也是一个学习WF4.0的好地方，打算把一些典型的问题和答案整理出来，方便大家查阅和学习，先整理几个出来，以后我会持续更新的，WF4.0论坛的地址是：http://social.msdn.microsoft.com/Forums/zh-CN/wfprerelease/threads。

1、Q:获取自定义活动的子活动：

    A:实现的代码

static void Main(string[] args)
{
    Activity act = new Workflow1();
    ShowChildren(act);
}

static void ShowChildren(Activity act, int level = 0)
{
    foreach (var a in WorkflowInspectionServices.GetActivities(act))
    {
        Console.WriteLine("{0}{1} ({2})", new string('.', level * 3),  a.DisplayName, a.GetType().Name);
        ShowChildren(a, level + 1);
    }
}

2、Q:在宿主设计器中，通过编程的方式在Flowchar添加arguments ：

    A：实现的代码：

designer = new WorkflowDesigner();
            ActivityBuilder builder = new ActivityBuilder();
            builder.Implementation = new Flowchart();
            designer.Load(builder);
            Grid.SetColumn(designer.View, 1);
            Grid.SetRow(designer.View, 0);
            rehostGrid.Children.Add(designer.View);
            DynamicActivityProperty property = new DynamicActivityProperty()
            {
                Name = "test",
                Type = typeof(InArgument<string>),

            };
            designer.Context.Services.GetService<ModelService>().Root.Properties["Properties"].Collection.Add(property);

3、Q:如何将代码方式工作流转化为Xaml格式的工作流。

    A：实现的代码，这个不支持lambda，先将其转换为VBRefrenceValue等：

ActivityBuilder ab1 = new ActivityBuilder();
            ab1.Name = "convert";           
            ab1.Implementation = GetServiceWorkflow();
            StringBuilder sb = new StringBuilder();
            StringWriter tw = new StringWriter(sb);
            XamlWriter xw = ActivityXamlServices.CreateBuilderWriter(new XamlXmlWriter(tw, new XamlSchemaContext()));
            XamlServices.Save(xw, ab1);
            Console.WriteLine(sb.ToString());

4、Q：IActivityTemplateFactory能否用在变量上

     A：可以，一个变量情况：

public class MyActWithVars : IActivityTemplateFactory
{
    public Activity Create(System.Windows.DependencyObject target)
    {
        var stringVar = new Variable<string>() { Name = "stringVar", Default = "Hello World" };            
        return new Sequence
        {
            Variables = { stringVar },
            Activities = 
            {                   
                new WriteLine
                {
                    Text = new VisualBasicValue<string>("stringVar")
                }
            }
        };            
    }
}

    多个变量的情况：

public class MyActWithVars : IActivityTemplateFactory
{
    public Activity Create(System.Windows.DependencyObject target)
    {
        var stringVar = new Variable<string>() { Name = "stringVar", Default = "Hello World" };
        var stringVar2 = new Variable<string>() { Name = "stringVar2", Default = "Good bye World" };
        var stringVar3 = new Variable<string>() { Name = "stringVar3", Default = "Another var" };            
        return new Sequence
        {
            Variables = { stringVar, stringVar2, stringVar3 },
            Activities = 
            {       
                // Add your activites here...
            }
        };            
    }
}

5、Q：怎样在dll中找出WF的活动：

    A：实现的代码

var types = from t in asm.GetExportedTypes()
                 where typeof(System.Activities.Activity).IsAssignableFrom(t) ||
                 typeof(System.Activities.Presentation.IActivityTemplateFactory).IsAssignableFrom(t)
                 select t.FullName;

6、Q：在宿主设计器上隐藏Arguments按钮：

    A：实现的代码

this.wd.Context.Services.GetService<DesignerView>().WorkflowShellBarItemVisibility = ShellBarItemVisibility.Variables;

ShellBarItemVisibility 枚举有如下值：None， Variables ，Arguments， Imports ，Zoom ，MiniMap ， All。

7、Q：宿主设计器中，如何由string来创建flowchar

    A：实现的代码

WorkflowDesigner wd = new WorkflowDesigner();
  wd.Load(XamlServices.Load(new StringReader(s)));

8、Q：在设计时动态添加Argument到自定义动中：

    A：实现的代码：

[ContentProperty("Parameters")]
    [Designer(typeof(TAGLIST_SetPropertyDesigner))]
    public sealed class TAGLIST_SetProperty : Extended_Sequence
    {

        [CategoryAttribute("Input/Output")]        
        public InOutArgument<TAGLIST> Taglist { get; set; }

        private Collection<Argument> parameters;

        [Editor(typeof(ArgumentCollectionPropertyEditor), typeof(DialogPropertyValueEditor))]
        public Collection<Argument> Parameters
        {
            get
            {
                if (this.parameters == null)
                {
                    this.parameters = new Collection<Argument>();
                }
                return this.parameters;
            }
        }

        protected override void CacheMetadata(NativeActivityMetadata metadata)
        {<br/>            base.CacheMetadata(metadata);
            Collection<RuntimeArgument> arguments = new Collection<RuntimeArgument>();
            for (int k = 0; k < this.Parameters.Count; k++)
            {
                RuntimeArgument argument3 = new RuntimeArgument("Argument" + k, this.Parameters[k].ArgumentType, this.Parameters[k].Direction, true);
                metadata.Bind(this.Parameters[k], argument3);
                arguments.Add(argument3);

                metadata.AddArgument(argument3);
            }  
            //metadata.SetArgumentsCollection(arguments);
        } 

        protected override void Execute(NativeActivityContext context)
        {
            TAGLIST tl = Taglist.Get(context);
            foreach (Argument arg in this.parameters)
            {
                object inp = arg.Get(context);   //Throws the exception

                if (inp != null && inp.GetType() == typeof(TAG))
                {
                    TAG tag = (TAG)inp;
                    tl.SetProperty(tag.Key, tag.Value);
                }
            }
            Taglist.Set(context, tl);
        }
    }

9、Q： 自定义活动的属性设置为一个对话框

     A：实现的代码

 public string FileName { get; set; }
      static SimpleCodeActivity()
        {
            AttributeTableBuilder builder = new AttributeTableBuilder();

            builder.AddCustomAttributes(typeof(SimpleCodeActivity), "FileName", new EditorAttribute(typeof(FilePickerEditor), typeof(DialogPropertyValueEditor)));
            MetadataStore.AddAttributeTable(builder.CreateTable());
        }

     FilePickerEditor：

class FilePickerEditor : DialogPropertyValueEditor
    {
        public FilePickerEditor()
        {
            this.InlineEditorTemplate = new DataTemplate();

            FrameworkElementFactory stack = new FrameworkElementFactory(typeof(StackPanel));
            stack.SetValue(StackPanel.OrientationProperty, Orientation.Horizontal);
            FrameworkElementFactory label = new FrameworkElementFactory(typeof(Label));
            Binding labelBinding = new Binding("Value");
            label.SetValue(Label.ContentProperty, labelBinding);
            label.SetValue(Label.MaxWidthProperty, 90.0);
            
            stack.AppendChild(label);

            FrameworkElementFactory editModeSwitch = new FrameworkElementFactory(typeof(EditModeSwitchButton));
            
            editModeSwitch.SetValue(EditModeSwitchButton.TargetEditModeProperty, PropertyContainerEditMode.Dialog);
            
            stack.AppendChild(editModeSwitch);

            this.InlineEditorTemplate.VisualTree = stack;
        }

        public override void ShowDialog(PropertyValue propertyValue, IInputElement commandSource)
        {
            Microsoft.Win32.OpenFileDialog ofd = new Microsoft.Win32.OpenFileDialog();
            if (ofd.ShowDialog() == true)
            {
                
                propertyValue.Value = ofd.FileName.Substring(ofd.FileName.LastIndexOf('\\')+1);
            }
        }
    }

   DataTemplate：

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:pres="clr-namespace:System.Activities.Presentation.PropertyEditing;assembly=System.Activities.Presentation"
                    x:Class="Microsoft.Samples.Activities.Designer.PropertyGridExtensibility.EditorResources">
    <DataTemplate x:Key="FilePickerTemplate">
        <StackPanel Orientation="Horizontal" >
            <Label Content="{Binding Path=Value}" MaxWidth="80">
                <Label.ToolTip>
                    <TextBlock Text="{Binding Path=Value}"/>
                </Label.ToolTip>
            </Label>
            
            <pres:EditModeSwitchButton TargetEditMode="{x:Static pres:PropertyContainerEditMode.Dialog}"/>
        </StackPanel>
    </DataTemplate>

</ResourceDictionary>

10、Q：ToolboxControl ：Auto Expand/Collapse

      A:实现的代码

tbc.CategoryItemStyle = new System.Windows.Style(typeof(TreeViewItem))
{
    Setters = {
        new Setter(TreeViewItem.IsExpandedProperty, false)
    }
};

11、Q：如何在宿主设计器上直接打开活动：

      A：实现的代码：

      XAML部分:

<Window x:Class="WpfApplication15.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid Name="Foo">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="3*"/>
        </Grid.ColumnDefinitions>
        <Button Grid.Column="0" Click="Button_Click">Click Me</Button>
    </Grid>
</Window>

    CS部分:

using System.Activities;
using System.Activities.Core.Presentation;
using System.Activities.Presentation;
using System.Activities.Presentation.Model;
using System.Activities.Presentation.Services;
using System.Activities.Presentation.View;
using System.Activities.Statements;
using System.Collections.Generic;
using System.Linq;
using System.Windows;
using System.Windows.Controls;

namespace WpfApplication15
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {

        WorkflowDesigner wd;
        public MainWindow()
        {
            InitializeComponent();
            // register metadata
            (new DesignerMetadata()).Register();
            // create the workflow designer
            wd = new WorkflowDesigner();
            wd.Load(new Sequence
        {

            Activities =
         {
             
             new Sequence
            {
                 Activities = 
                 {
                     new ForEach<string>
                   {
                        Body = new ActivityAction<string>
                        {
                            Argument = new DelegateInArgument<string> { Name="foo" },
                             Handler = 
                               new Sequence
                               {
                                    Activities = 
                                    {
                                       new If()
                                       {
                                           Else = new WriteLine(),
                                           Then = new WriteLine()
                                       }
                                    }
                               }
                      }
                   }
                  }
                }
                }
        });

            Grid.SetColumn(wd.View, 1);
            Foo.Children.Add(wd.View);



        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            ModelService modelService = wd.Context.Services.GetService<ModelService>();
            IEnumerable<ModelItem> activityCollection = modelService.Find(modelService.Root, typeof(Activity));
            Selection.Select(wd.Context, activityCollection.ElementAt(5));
        }
    }
}

12、Q：WorkflowApplication加载持久化的工作流：

      A：实现的代码：

WorkflowApplication application = new WorkflowApplication(workflowDefinition);
application.InstanceStore = new SqlWorkflowInstanceStore(...);
application.Load(id);
application.ResumeBookmark(...);

13、Q：WF4.0活动的表达式编辑器使用的语言是什么？

       A：VB

14、Q：将 xaml工作流转换成C#工作流：

     A：参考：http://blogs.msdn.com/mwinkle/archive/2009/06/10/types-metatypes-and-bears-oh-my.aspx

15、Q：如何在设计器上验证当前选择和拖拽的活动

      A：WF4.0验证框架包含三个辅助活动，它帮助您验证WF有关的活动。这些辅助活动是GetParentChain，GetChilSubtree和GetWorkflowTree，

他们是在Constraints里面，就像你将使用AssertValidation。下面是一个代码片段：

 static Constraint CheckParent()

        {

            Variable<ActivityCity> element = new Variable<ActivityCity>();

            Variable<ValidationContext> context = new Variable<ValidationContext>();

            Variable<bool> result = new Variable<bool>();

            Variable<WorkflowElement> parent = new Variable<WorkflowElement>();

            return new Constraint<ActivityCity>

            {                   

                Body = new ActivityAction<ActivityCity,ValidationContext>

                {                    

                    Argument1 = element,

                    Argument2 = context,

                    Handler = new Sequence

                    {

                        Variables =

                        {

                            result 

                        },

                        Activities =

                        {

                            new ForEach<WorkflowElement>

                            {                                

                                Values = new GetParentChain

                                {

                                    ValidationContext = context                                    

                                },

                                Body = new ActivityAction<WorkflowElement>

                                {                                    

                                    Argument = parent, 

                                    Handler = new If()

                                    {                                          

                                        Condition = new InArgument<bool>((env) => object.Equals(parent.Get(env).GetType(),typeof(ActivityCountry))),

                                        Then = new Assign<bool>

                                        {

                                            Value = true,

                                            To = result

                                        }

                                    }

                                }                                

                            },

                            new AssertValidation

                            {

                                Assertion = new InArgument<bool>(result),

                                Message = new InArgument<string> ("ActivityCity has to be inside an ActivityCountry"),

                                ErrorCode = new InArgument<string> ("Build-1002"),

                                PropertyName = new InArgument<string>((env) => element.Get(env).name)

                            }

                        }

                    }

                }

            };

        }

16、Q：如何在WF4.0表达式编辑器上使用Generic List, Hash table, Array

      A：您将需要使用VB的对象和集合初始化语法

New Order With { .OrderId = 23, .Customer = new Customer With { .Id = 43, .Name = "Joe" }, .OrderItems = new List (Of OrderItem) From { new OrderItem With { .ID= 5335, Price = 234.23 } } } 
New List(Of String) From { "hello", "world" }
New Dictionary(Of String, Object) From { {"hello", 42　}, {"world", new ApplicationException() } }

17、Q：获取Flow switch表达式字符串

      A：实现代码：

ModelItem item = designer.Context.Services.GetService<ModelService>().Root;
            WorkflowViewElement element = item.View as WorkflowViewElement;
            if (element.Content != null)
            {
                Label lab = new Label();
                lab.Content = item.Properties["Expression"].ComputedValue.ToString();
                Grid grid = element.Content as Grid;
                grid.Children.Add(lab);
            }
        }

18、Q：在C#中通过Default值动态创建变量。

       A：如果name为：zhu ，lastname为qilin，New Class1().name + New Class1().lastName求出的值为"zhuqilin"，直接看代码：

  string assemblyname = typeof(Class1).Assembly.GetName().Name;

            string ns = typeof(Class1).Namespace;

            VisualBasicSettings vbSettings = new VisualBasicSettings();

            vbSettings.ImportReferences.Add(new VisualBasicImportReference

            {

                Assembly = assemblyname,

                Import = ns,

            });


            Sequence wf = new Sequence
            {
                Variables =
                {
                    new Variable<string> {Name = "n2", Default = new VisualBasicValue<string>("New Class1().name + New Class1().lastName")}

                },
                            Activities =
                {
                    new WriteLine { Text = new VisualBasicValue<string>("n2")}, 
                }
            };

            VisualBasic.SetSettings(wf, vbSettings);

            WorkflowInvoker.Invoke(wf);
            Console.Read();

 

19、Q:宿主工作流设计器中验证ActivityBuilder

      A:代码如下：

designer.Flush();
Activity a = ActivityXamlServices.Load(new StringReader(designer.Text)); //would return a DynamicActivity for your case
ActivityValidationServices.Validate(a);

 

 

 

（全文完）

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