I am completely new to Qt.

I started with a new Qt4 GUI Application.

Using the designer, I have created a menu like so:

    File
     - Exit

How do I get an action associated with the menu item?

I found something called the &#39;Signals and slots editor&#39; but have no idea how to use it.

How to connect menu click with action in Qt Creator?

As a fairly experienced ASP.Net developer just recently starting using MVC, I find myself struggling a bit to change my mindset from a traditional &quot;server control and event handler&quot; way of doing things, into the more dynamic MVC way of things. I think I am slowly getting there, but sometimes the MVC &quot;magic&quot; throws me off.

My current scenario is to create a web page that allows the user to browse a local file, upload it to the server and repeat this until he has a list of files to work with. When he is happy with the file list (which will be displayed in a grid on the page), he will click a button to process the files and extract some data that will be stored in a database.

The last part is not so important, right now I am struggling with something as trivial as building up a list of files, and persisting that list between requests. In the traditional approach this would be extremely simple - the data would be persisted in ViewState. But in MVC I need to pass the data between the controller and the views, and I don&#39;t fully get how this is supposed to work.

I guess I better post my rather incomplete attempt of coding this to explain the problem.

In order to keep my file list data, I have created a viewmodel that is basically a typed list of files, along with some extra metadata:

    public class ImportDataViewModel
    {
        public ImportDataViewModel()
        {
            Files = new List&lt;ImportDataFile&gt;();
        }

        public List&lt;ImportDataFile&gt; Files { get; set; }
    ...

In the view, I have a form for browsing and uploading the file:

    &lt;form action=&quot;AddImportFile&quot; method=&quot;post&quot; enctype=&quot;multipart/form-data&quot;&gt;
      &lt;label for=&quot;file&quot;&gt;
        Filename:&lt;/label&gt;
      &lt;input type=&quot;file&quot; name=&quot;file&quot; id=&quot;file&quot; /&gt;
      &lt;input type=&quot;submit&quot; /&gt;
      &lt;/form&gt;

The view is using the viewmodel as its model:

    @model MHP.ViewModels.ImportDataViewModel

This will send the file to my action:

    public ActionResult AddImportFile(HttpPostedFileBase file, ImportDataViewModel importData)
        {

            if (file.ContentLength &gt; 0)
            {
                ImportDataFile idFile = new ImportDataFile { File = file };
                importData.Files.Add(idFile);
            }

            return View(&quot;DataImport&quot;, importData);
        }

This action returns the view for the DataImport page along with the viewmodel instance containing the list of files.

This works nicely up to a certain point, I can browse a file and upload it, and I can see the viewmodel data inside the action, and then also if I put a breakpoint inside the view and debug &quot;this.Model&quot;, everything is fine.

But then, if I try to upload another file, when putting a breakpoint inside the AddImportFile action, the importData parameter is empty. So the view is obviously not passing the current instance of its model to the action. 

In the MVC samples I have been through, the model instance is &quot;magically&quot; passed to the action method as a parameter, so why is it empty now?

I assume the real problem is my limited understanding of MVC, and that there is probably a very simple solution to this. Anyways, I would be extremely grateful if somebody could point me in the right direction.










ASP.Net MVC and state - how to keep state between requests

When I&#39;m trying to use params in an Action delegate...

    private Action&lt;string, params object[]&gt; WriteToLogCallBack;

I received this design time error:
&gt;Invalid token &#39;params&#39; in class, struct, or interface member declaration

Any help!

Can I use params in Action or Func delegates?

I want to pass the movie url from my dynamically generated button to MediaPlayer:

    [button addTarget:self action:@selector(buttonPressed:) withObject:[speakers_mp4 objectAtIndex:[indexPath row]] forControlEvents:UIControlEventTouchUpInside];

but `action:@selector() withObject:` does not work?

Is there any other solution?

Thanks for help!

Passing parameters on button action:@selector

I want to create a picture chooser from gallery. I use code 

     intent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
     startActivityForResult(intent, TFRequestCodes.GALLERY);

My problem is that in this activity and video files are displayed. Is there a way to filter displayed files so that no video files will be displayed in this activity?

android pick images from gallery

For our web application I need to save the order of the fetched and displayed items depending on the view - or to be precise - the controller and action that generated the view (and the user id of course, but that&#39;s not the point here).

Instead of just giving an identifier myself in each controller action (in order to use it for some view-dependant sorting of DB outputs), I thought that it would be safer and easier to create this identifier automatically from the controller and action method it gets called from.

How can I get the name of the controller and action from within the action method in a controller? Or do I need reflection for that?

Get controller and action name from within controller?

With real examples and their use, can someone please help me understand:

 1. When do we need a [`Func&lt;T, ..&gt;`][1] delegate? 
 2. When do we need an [`Action&lt;T&gt;`][2] delegate?
 3. When do we need a [`Predicate&lt;T&gt;`][3] delegate?


  [1]: https://docs.microsoft.com/en-us/dotnet/api/system.func-1?view=netcore-3.1
  [2]: https://docs.microsoft.com/en-us/dotnet/api/system.action-1?view=netcore-3.1
  [3]: https://docs.microsoft.com/en-us/dotnet/api/system.predicate-1?view=netcore-3.1

Func vs. Action vs. Predicate

Since API level 16 (Jelly Bean), there is the possibility to add actions to a notification with

    builder.addAction(iconId, title, intent);

But when I add an action to a notification and the action is pressed, the notification is not going to be dismissed.
When the notification itself is being clicked, it can be dismissed with

    notification.flags = Notification.FLAG_AUTO_CANCEL;

or

    builder.setAutoCancel(true);

But obviously, this has nothing to with the actions associated to the notification.

Any hints? Or is this not part of the API yet? I did not find anything.

How to dismiss notification after action has been clicked

I&#39;m trying to change the form action based on the selected value from a dropdown menu.

Basically, the HTML looks like this:

    &lt;form class=&quot;search-form&quot; id=&quot;search-form&quot; method=&quot;post&quot; accept-charset=&quot;UTF-8&quot; action=&quot;/search/user&quot;&gt;
    &lt;select id=&quot;selectsearch&quot; class=&quot;form-select&quot; name=&quot;selectsearch&quot;&gt;
    &lt;option value=&quot;people&quot;&gt;Search people&lt;/option&gt;
    &lt;option value=&quot;node&quot;&gt;Search content&lt;/option&gt;
    &lt;/select&gt;
    
    &lt;label&gt;Enter your keywords: &lt;/label&gt;
     &lt;input type=&quot;text&quot; class=&quot;form-text&quot; value=&quot;&quot; size=&quot;40&quot; id=&quot;edit-keys&quot; name=&quot;keys&quot; maxlength=&quot;255&quot; /&gt;
    
    &lt;input type=&quot;submit&quot; class=&quot;form-submit&quot; value=&quot;Search&quot; id=&quot;edit-submit&quot; name=&quot;search&quot;/&gt;
    &lt;/form&gt;

If &quot;people&quot; is selected, (which it is by default), the action should be &quot;/search/user&quot;, and if content is selected, the action should be &quot;/search/content&quot;

I&#39;m still searching around, but haven&#39;t been able to find out how to do this. 



JavaScript: how to change form action attribute value based on selection?

I was working with the Action Delegates in C# in the hope of learning more about them and thinking where they might be useful.

Has anybody used the Action Delegate, and if so why? or could you give some examples where it might be useful?



Uses of Action delegate in C#

What is the best way to replace links with images using Razor in MVC3.  I simply doing this at the moment:

    &lt;a href=&quot;@Url.Action(&quot;Edit&quot;, new { id=MyId })&quot;&gt;&lt;img src=&quot;../../Content/Images/Image.bmp&quot;, alt=&quot;Edit&quot; /&gt;&lt;/a&gt; 

Is there a better way?

Action Image MVC3 Razor

I am reading through [argparse][1] module. I got stuck as what to metavar and action means

    &gt;&gt;&gt; parser.add_argument(&#39;integers&#39;, metavar=&#39;N&#39;, type=int, nargs=&#39;+&#39;,
    ...                     help=&#39;an integer for the accumulator&#39;)
    &gt;&gt;&gt; parser.add_argument(&#39;--sum&#39;, dest=&#39;accumulate&#39;, action=&#39;store_const&#39;,
    ...                     const=sum, default=max,
    ...                     help=&#39;sum the integers (default: find the max)&#39;)

I might have missed but from what I read, I could not find definitions for `metavar` and 
`action (action=&quot;store_const&quot;, etc)`. what do they actually mean?

  [1]: http://docs.python.org/dev/library/argparse.html

What does metavar and action mean in argparse in Python?

I have the default Route in Global.asax:

     RouteTable.Routes.MapHttpRoute(
             name: &quot;DefaultApi&quot;,
             routeTemplate: &quot;api/{controller}/{id}&quot;,
             defaults: new { id = System.Web.Http.RouteParameter.Optional }
             );

I wanted to be able to target a specific function, so I created another route:

    RouteTable.Routes.MapHttpRoute(
             name: &quot;WithActionApi&quot;,
             routeTemplate: &quot;api/{controller}/{action}/{id}&quot;,
             defaults: new { id = System.Web.Http.RouteParameter.Optional }
             );

So, in my controller, I have:

        public string Get(int id)
        {
            return &quot;object of id id&quot;;
        }        
        
        [HttpGet]
        public IEnumerable&lt;string&gt; ByCategoryId(int id)
        {
            return new string[] { &quot;byCategory1&quot;, &quot;byCategory2&quot; };
        }

Calling `.../api/records/bycategoryid/5` will give me what I want.
However, calling `.../api/records/1` will give me the error 

&gt;Multiple actions were found that match the request: ...

I understand why that is - the routes just define what URLs are valid, but when it comes to function matching, both `Get(int id)` and `ByCategoryId(int id)` match `api/{controller}/{id}`, which is what _confuses_ the framework.

What do I need to do to get the default API route to work again, and keep the one with `{action}`? I thought of creating a different controller named `RecordByCategoryIdController` to match the default API route, for which I would request `.../api/recordbycategoryid/5`. However, I find that to be a &quot;dirty&quot; (thus unsatisfactory) solution. I&#39;ve looked for answers on this and no tutorial out there on using a route with `{action}` even mentions this issue.

Web API Routing - api/{controller}/{action}/{id} &quot;dysfunctions&quot; api/{controller}/{id}

How can the action for a custom UIBarButtonItem in Swift be set?

The following code successfully places the button in the navigation bar:

    var b = UIBarButtonItem(title: &quot;Continue&quot;, style: .Plain, target: self, action:nil)
    self.navigationItem.rightBarButtonItem = b

Now, I would like to call `func sayHello() { println(&quot;Hello&quot;) }` when the button is touched. My efforts so far:

    var b = UIBarButtonItem(title: &quot;Continue&quot;, style: .Plain, target: self, action:sayHello:)
    // also with `sayHello` `sayHello()`, and `sayHello():`

and..

    var b = UIBarButtonItem(title: &quot;Continue&quot;, style: .Plain, target: self, action:@selector(sayHello:))
    // also with `sayHello` `sayHello()`, and `sayHello():`

and..

    var b = UIBarButtonItem(title: &quot;Continue&quot;, style: .Plain, target: self, action:@selector(self.sayHello:))
    // also with `self.sayHello` `self.sayHello()`, and `self.sayHello():`

Note that `sayHello()` appears in the intellisense, but does not work.

Thanks for your help.

EDIT: For posterity, the following works:

    var b = UIBarButtonItem(title: &quot;Continue&quot;, style: .Plain, target: self, action:&quot;sayHello&quot;)

How to set the action for a UIBarButtonItem in Swift

    private void Include(IList&lt;string&gt; includes, Action action)
    {
        if (includes != null)
        {
            foreach (var include in includes)
                action(&lt;add include here&gt;);
        }
    }

  I want to call it like that 
  

    this.Include(includes, _context.Cars.Include(&lt;NEED TO PASS each include to here&gt;));

  The idea is pass each include to the method.

How can I pass a parameter in Action?

How would you model a system that handles permissions for carrying out certain actions inside an application?

Modelling a permissions system

What is the difference between `action` and `actionListener`, and when should I use `action` versus `actionListener`?

Differences between action and actionListener

Today I was thinking about declaring this:

    private delegate double ChangeListAction(string param1, int number);

but why not use this: 

    private Func&lt;string, int, double&gt; ChangeListAction;

or if `ChangeListAction` would have no return value I could use:

    private Action&lt;string,int&gt; ChangeListAction;

so where is the advantage in declaring a delegate with the `delegate` keyword?

Is it because of .NET 1.1, and with .NET 2.0 came `Action&lt;T&gt;` and with .NET 3.5 came `Func&lt;T&gt;`?

Creating delegates manually vs using Action/Func delegates

In Ansible (1.9.4) or 2.0.0

I ran the following action:

    - debug: msg=&quot;line1 \n {{ var2 }} \n line3 with var3 = {{ var3 }}&quot;


**$ cat roles/setup_jenkins_slave/tasks/main.yml**

    - debug: msg=&quot;Installing swarm slave = {{ slave_name }} at {{ slaves_dir }}/{{ slave_name }}&quot;
      tags:
        - koba
    
    - debug: msg=&quot;1 == Slave properties = fsroot[ {{ slave_fsroot }} ], master[ {{ slave_master }} ], connectingToMasterAs[ {{ slave_user }} ], description[ {{ slave_desc }} ], No.Of.Executors[ {{ slave_execs }} ], LABELs[ {{ slave_labels }} ], mode[ {{ slave_mode }} ]&quot;
      tags:
        - koba
    
    
    - debug: msg=&quot;print(2 == Slave properties = \n\nfsroot[ {{ slave_fsroot }} ],\n master[ {{ slave_master }} ],\n connectingToMasterAs[ {{ slave_user }} ],\n description[ {{ slave_desc }} ],\n No.Of.Executors[ {{ slave_execs }} ],\n LABELs[ {{ slave_labels }} ],\n mode[ {{ slave_mode }} ])&quot;
      tags:
        - koba

But this is not printing the variable with new lines (for the 3rd debug action)?




Ansible - Print message - debug: msg=&quot;line1 \n {{ var2 }} \n line3 with var3 = {{ var3 }}&quot;

All the examples I can find about Func&lt;&gt; and Action&lt;&gt; are **simple** as in the one below where you see *how* they technically work but I would like to see them used in examples where they solve problems that previously could not be solved or could be solved only in a more complex way, i.e. I know how they work and I can see they are **terse and powerful**, so I want to understand them in a **larger sense** of what kinds of problems they solve and how I could use them in the design of applications.

**In what ways (patterns) do you use Func&lt;&gt; and Action&lt;&gt; to solve real problems?**

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    
    namespace TestFunc8282
    {
        class Program
        {
            static void Main(string[] args)
            {
                //func with delegate
                Func&lt;string, string&gt; convert = delegate(string s)
                {
                    return s.ToUpper();
                };
    
                //func with lambda
                Func&lt;string, string&gt; convert2 = s =&gt; s.Substring(3, 10);
    
                //action
                Action&lt;int,string&gt; recordIt = (i,title) =&gt;
                    {
                        Console.WriteLine(&quot;--- {0}:&quot;,title);
                        Console.WriteLine(&quot;Adding five to {0}:&quot;, i);
                        Console.WriteLine(i + 5);
                    };
    
                Console.WriteLine(convert(&quot;This is the first test.&quot;));
                Console.WriteLine(convert2(&quot;This is the second test.&quot;));
                recordIt(5, &quot;First one&quot;);
                recordIt(3, &quot;Second one&quot;);
    
                Console.ReadLine();
    
            }
        }
    }

How do you use Func&lt;&gt; and Action&lt;&gt; when designing applications?

Sometimes, when using `&lt;h:commandLink&gt;`, `&lt;h:commandButton&gt;` or `&lt;f:ajax&gt;`, the `action`, `actionListener` or `listener` method associated with the tag are simply not being invoked. Or, the bean properties are not updated with submitted `UIInput` values.

What are the possible causes and solutions for this?


commandButton/commandLink/ajax action/listener method not invoked or input value not set/updated

Say I have an Article model, and in the article &#39;new&#39; view I have two buttons, &quot;Publish&quot; and &quot;Save Draft&quot;.

My question is how can I know which button is clicked in the controller.

I already have a solution but I think there must be a better way.
What I currently used in the view is:

    &lt;div class=&quot;actions&quot;&gt;
      &lt;%= f.submit &quot;Publish&quot; %&gt;
      &lt;%= f.submit &quot;Save Draft&quot;, :name =&gt; &quot;commit&quot; %&gt;
    &lt;/div&gt;

So in the controller, I can use the **params[:commit]** string to handle that action. 

    def create
      @article = Article.new(params[:article])
      if params[:commit] == &quot;Publish&quot;
        @article.status = &#39;publish&#39;
        // detail omitted
      end

      @article.save
    end

But I think using the view related string is not good. Could you tell me another way to accomplish this?

**UPDATE**: Since these buttons are in the same form, they&#39;re all going to the &#39;create&#39; action, and that&#39;s OK for me. What I want is to handle that within the create action, such as give the Article model a &#39;status&#39; column and holds &#39;public&#39; or &#39;draft&#39;.

Rails: Multi-submit buttons in one Form

I am using the hub- feature of SignalR (https://github.com/SignalR/SignalR) to publish messages to all subscribed clients:

    public class NewsFeedHub : Hub
    public void Send(string channel, string content)
    {
        Clients[channel].addMessage(content);
    }

This works fine when calling &quot;Send&quot; via Javascript, but I would also like the web application to publish messages (from within an ASP.NET MVC action method). I already tried instantiating a new object ob NewsFeedHub and calling the Send method, but this results in an error (as the underlying &quot;Connection&quot; of the Hub is not set). Is there a way to use the Hub without a connection?

SignalR + posting a message to a Hub via an action method

Is there a way to execute a JSF managed bean action when a page is loaded?

If that&#39;s relevant, I&#39;m currently using JSF 1.2.

Invoke JSF managed bean action on page load

in ASP.NET MVC when my action will not return anything I use `return new EmptyResult()`
or `return null`

is there any difference?

return new EmptyResult() VS return NULL

I&#39;ve got a jsf 1.2 form with two buttons and several input fields. The first button discards the entered values and repopulates the page with values from a db, the second button saves the entered values. The problem occurs when the user presses enter while the cursor is in one of the input fields, the form gets submitted and the action associated with the first button gets executed.

The code looks like this:

    &lt;h:commandButton action=&quot;#{bean.reset}&quot; value=&quot;Reset&quot; /&gt;
    &lt;h:commandButton action=&quot;#{bean.save}&quot; value=&quot;Save&quot; /&gt;

    &lt;!-- h:datatable with several h:inputText elements --&gt;

Is it possible to declare a specific button as the default action when pressing enter? Is this behaviour actually specified somewhere?

All Action Solutions on Gang of Coders

Total of 26 Action Solutions