I&#39;m looking for alternative ways to push view controllers instantiated on storyboard programmatically.
I&#39;ve actually found two ways, that I use to go to the next view, but also to go back to the previous:

 1. using `pushViewController`:


        UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@&quot;MainStoryboard&quot; bundle: nil]; 
        LocationWebView *lvc = [storyboard instantiateViewControllerWithIdentifier:@&quot;LocationWebView&quot;];
        [self.navigationController pushViewController:lvc animated:YES];



 2. performing `Segue` programmatically:

        [self performSegueWithIdentifier: @&quot;SongSegue&quot; sender: self];


Do you have some hints on alternatives and on the best way this operation should be performed? Note that I&#39;m not referring to modal views.

Alternative ways to push view controllers with storyboard programmatically

Is there a way to check if a modal view is present? I&#39;d like to run a method only if a modal view is present. Also, if I have multiple modal views, is there a way to check if a certain modal view is present.

I use the following code to present and dismiss modal views:

        [self presentModalViewController:myModalView animated:YES];
        [self dismissModalViewControllerAnimated:YES];
    

Thank you in advance!

Cheers,
Evan

PS. My modal view has a view controller, but I&#39;d like to check if the modal view is present from a separate class that is running asynchronously.

iOS - How to check if a modal view is present

In Scala, for many (all?) types of collections you can create views.

What exactly is a view and for which purposes are views useful?

What are views for collections and when would you want to use them?

Is it possible to display a view from another controller?

Say for example I have a `CategoriesController` and a `Category/NotFound.aspx` view. While in the `CategoriesController`, I can easly return `View(&quot;NotFound&quot;)`.

Now say I have a `ProductsController` and an action and view to add a product. However, this action requires that we have a Category to add the Product to. For example, `Products/Add/?catid=10`.

If I am not able to find the Category based on `catid`, I want to show the `NotFound` view from the Categories controller instead of creating a `CategoryNotFound` view under the Products controller.

Is this possible or am I structuring things in the wrong way? Is there a good way to do this?


Display a view from another controller in ASP.NET MVC

I am confused about a few points:

1. What is the difference between a stored procedure and a view?

2. When should I use stored procedures, and when should I use views, in SQL Server?

3. Do views allow the creation of dynamic queries where we can pass parameters? 

4. Which one is the fastest, and on what basis is one faster than the other?

5. Do views or stored procedures allocate memory permanently?

6. What does it mean if someone says that views create a virtual table, while procedures create a materials table?

Please let me know about more points, if there are any.

What is the difference between a stored procedure and a view?

Can we pass a parameter to a view in Microsoft SQL Server?

I tried to `create view` in the following way, but it doesn&#39;t work:  

    create or replace view v_emp(eno number) as select * from emp where emp_id=&amp;eno;



Can we pass parameters to a view in SQL?

Just started using Xcode 4.5 and I got this error in the console:

&gt;Warning: Attempt to present &lt; finishViewController: 0x1e56e0a0 &gt; on &lt; ViewController: 0x1ec3e000&gt; whose view is not in the window hierarchy!

The view is still being presented and everything in the app is working fine. Is this something new in iOS 6?

This is the code I&#39;m using to change between views:

    UIStoryboard *storyboard = self.storyboard;
    finishViewController *finished = 
    [storyboard instantiateViewControllerWithIdentifier:@&quot;finishViewController&quot;];
                
    [self presentViewController:finished animated:NO completion:NULL];

Attempt to present UIViewController on UIViewController whose view is not in the window hierarchy

I occasionally have to add a class to an html element based on a condition. The problem is I can&#39;t figure out a clean way of doing it. Here&#39;s an example of the stuff I&#39;ve tried:

    &lt;div &lt;%= if @status = &#39;success&#39;; &quot;class=&#39;ok&#39;&quot;; end %&gt;&gt;
       some message here
    &lt;/div&gt;

**OR**

    &lt;% if @status == &#39;success&#39; %&gt;
       &lt;div class=&#39;success&#39;&gt;
    &lt;% else %&gt;
       &lt;div&gt;
    &lt;% end %&gt;
       some message here
    &lt;/div&gt;

I don&#39;t like the first approach because it&#39;s crowded looking and hard to read. I don&#39;t like the second approach because the nesting is screwed up. It&#39;d be nice to put it in the model, (something like `@status.css_class`), but that doesn&#39;t belong there. What do most people do?

What&#39;s an elegant way to conditionally add a class to an HTML element in a view?

I have two tables and I need to create a view. The tables are:

    credit_orders(id, client_id, number_of_credits, payment_status)
    credit_usage(id, client_id, credits_used, date)

I use the following query to do this. The query without the &quot;create view&quot; part works well but with &quot;create view&quot;, it shows the error &quot;View&#39;s SELECT contains a subquery in the FROM clause&quot;. What could be the issue &amp; possible solution:

    create view view_credit_status as 
    (select credit_orders.client_id, 
            sum(credit_orders.number_of_credits) as purchased, 
            ifnull(t1.credits_used,0) as used 
     from credit_orders
     left outer join (select * from (select credit_usage.client_id, 
                                            sum(credits_used) as credits_used 
                                     from credit_usage 
                                     group by credit_usage.client_id) as t0
                      ) as t1 on t1.client_id = credit_orders.client_id
     where credit_orders.payment_status=&#39;Paid&#39;
     group by credit_orders.client_id)

View&#39;s SELECT contains a subquery in the FROM clause

I have come to a point where I need to pass certain variables to all of my views (mostly custom authentication type variables).

I was told writing my own context processor was the best way to do this, but I am having some issues.

My settings file looks like this

    TEMPLATE_CONTEXT_PROCESSORS = (
        &quot;django.contrib.auth.context_processors.auth&quot;,
        &quot;django.core.context_processors.debug&quot;,
        &quot;django.core.context_processors.i18n&quot;,
        &quot;django.core.context_processors.media&quot;,
        &quot;django.contrib.messages.context_processors.messages&quot;,
        &quot;sandbox.context_processors.say_hello&quot;, 
    )

As you can see, I have a module called &#39;context_processors&#39; and a function within that called &#39;say_hello&#39;.

Which looks like

    def say_hello(request):
        	return {
	        	&#39;say_hello&#39;:&quot;Hello&quot;,
            }

Am I right to assume I can now do the following within my views?

    {{ say_hello }}

Right now, this renders to nothing in my template.

My view looks like

    from django.shortcuts import render_to_response

    def test(request):
        	return render_to_response(&quot;test.html&quot;)

creating my own context processor in django

If you are going down the road of using views, how can you ensure good performance?

Or is it better not to use views in the first place and just incorporate the equivalent into your select statements?

MySql views performance

I&#39;m using devise for user auth, but I have nice mockups for the signup, login, etc. pages.
I&#39;ve already done the `rails generate devise:views User` command and have all of the views in the views folder, however, when I replaced the registration/new.html.erb with my own new.html.erb, nothing changes nor looks different. It&#39;s as if I had done anything.

Anyone know what I&#39;m doing wrong or at least how to successfully customize devise views

P.S. Is it important to note that I changed the route of devise/registration#new to /signup?

Customizing Devise views in Rails

I have to add a few columns to a table and I also need to add these columns to all the views that use this table.

Is it possible to get a list of all the views in a database that use a certain table?

How to find which views are using a certain table in SQL Server (2008)?

&gt; **Possible Duplicate:**  
&gt; [How to size an Android view based on its parent’s dimensions](https://stackoverflow.com/questions/2159320/how-to-size-an-android-view-based-on-its-parents-dimensions)  

&lt;!-- End of automatically inserted text --&gt;

how do I use `getMeasuredWidth()` and `getMeasuredHeight`? It always returns 0. what is the diffrence between this and `getHeight()` and `getWidth()`? 

Android: How to get a custom View&#39;s height and width?

I am making an ASP.NET MVC application with the razor engine.&lt;br /&gt;
And I was wondering if it&#39;s possible to use [Regions][1] in a view.

something like:

    #region blabla
        &lt;p&gt;@Model.Name&lt;/p&gt;
        &lt;p&gt;...&lt;/p&gt;
    #endregion

This does not work. Is there an alternative?

  [1]: http://msdn.microsoft.com/en-us/library/9a1ybwek.aspx

Regions In ASP.NET Views?

I have used both but what I am not clear is when I should prefer one over the other. I mean I know stored procedure can take in parameters...but really we can still perform the same thing using Views too right ? 

So considering performance and other aspects when and why should I prefer one over the other ?

Stored Procedures Vs. Views

I&#39;ve been googling around about this and can&#39;t find the right path. I&#39;m working on a Rails app that is using a method called local_assigns. This appears to be something in Rails or a gem, and not specific to my app, but it&#39;s used for rendering a partial in different contexts, such as this:

    &lt;% if local_assigns[:custom_name] %&gt;
      &lt;li&gt;&lt;%= custom_name %&gt;&lt;/li&gt;
    &lt;% else %&gt;

or also this:

    &lt;%= render &quot;discussions/complementary/#{local_assigns[:action] || params[:action]}&quot; %&gt;

Is this is Rails method? Where can I find more documentation about this? 

How does local_assigns work in Rails?

Is there a way to generate the views separately using the rails generate command? I would also be willing to install a gem to accomplish that task f one exists. Basically the scaffolding command gives me too much and I would rather code my controller by hand. However, writing the index view with a table for the records would not be very efficient.

Ruby on Rails Generating Views

I love pandas and have been using it for years and feel pretty confident I have a good handle on how to subset dataframes and deal with views vs copies appropriately (though I use a lot of assertions to be sure). I also know that there have been tons of questions about SettingWithCopyWarning, e.g. https://stackoverflow.com/questions/20625582/how-to-deal-with-settingwithcopywarning-in-pandas
and some great recent guides on wrapping your head around when it happens, e.g. [Understanding SettingWithCopyWarning in pandas](https://www.dataquest.io/blog/settingwithcopywarning/). 

But I also know specific things like the quote from [this answer](https://stackoverflow.com/a/17961468/8022335) are no longer in the most recent docs (`0.22.0`) and that many things have been deprecated over the years (leading to some inappropriate old SO answers), and that things are [continuing to change](https://stackoverflow.com/a/34908742/8022335). 

Recently after teaching pandas to complete newcomers with very basic general Python knowledge about things like avoiding chained-indexing (and using `.iloc`/`.loc`), I&#39;ve still struggled to provide *general rules of thumb* to know when it&#39;s important to pay attention to the `SettingWithCopyWarning` (e.g. when it&#39;s safe to ignore it). 

I&#39;ve personally found that the specific pattern of subsetting a dataframe according so some rule (e.g. slicing or boolean operation) and then modifying that subset, *independent of the original dataframe*, is a much more common operation than the docs suggest. In this situation we want to *modify the copy not the original* and the warning is confusing/scary to newcomers.

I know it&#39;s not trivial to know ahead of time  when a view vs a copy is returned, e.g.   
https://stackoverflow.com/questions/23296282/what-rules-does-pandas-use-to-generate-a-view-vs-a-copy  
https://stackoverflow.com/questions/26879073/checking-whether-data-frame-is-copy-or-view-in-pandas

So instead I&#39;m looking for the answer to a more general (beginner friendly) question: **when does performing an operation on a subsetted dataframe affect the original dataframe from which it was created, and when are they independent?**. 

I&#39;ve created some cases below that I think seem reasonable, but I&#39;m not sure if there&#39;s a &quot;gotcha&quot; I&#39;m missing or if there&#39;s any easier way to think/check this. I was hoping someone could confirm that my intuitions about the following use cases are correct as the pertain to my question above.

    import pandas as pd
    df1 = pd.DataFrame({&#39;A&#39;:[2,4,6,8,10],&#39;B&#39;:[1,3,5,7,9],&#39;C&#39;:[10,20,30,40,50]})
 
1) Warning: No    
   Original changed: No  

    # df1 will be unaffected because we use .copy() method explicitly 
    df2 = df1.copy()
    #
    # Reference: docs
    df2.iloc[0,1] = 100

2) Warning: Yes (I don&#39;t really understood why)    
   Original changed: No  

    # df1 will be unaffected because .query() always returns a copy
    #
    # Reference:
    # https://stackoverflow.com/a/23296545/8022335
    df2 = df1.query(&#39;A &lt; 10&#39;)
    df2.iloc[0,1] = 100

3) Warning: Yes  
   Original changed: No

    # df1 will be unaffected because boolean indexing with .loc
    # always returns a copy
    #
    # Reference:
    # https://stackoverflow.com/a/17961468/8022335
    df2 = df1.loc[df1[&#39;A&#39;] &lt; 10,:]
    df2.iloc[0,1] = 100

4) Warning: No  
   Original changed: No

    # df1 will be unaffected because list indexing with .loc (or .iloc)
    # always returns a copy
    #
    # Reference:
    # Same as 4)
    df2 = df1.loc[[0,3,4],:]
    df2.iloc[0,1] = 100

5) Warning: No  
   Original changed: Yes (confusing to newcomers but makes sense)  

    # df1 will be affected because scalar/slice indexing with .iloc/.loc
    # always references the original dataframe, but may sometimes 
    # provide a view and sometimes provide a copy
    #
    # Reference: docs
    df2 = df1.loc[:10,:]
    df2.iloc[0,1] = 100

**tl;dr**
When creating a new dataframe from the original, changing the new dataframe:  
Will change the original when **scalar/slice indexing with .loc/.iloc is used to create the new dataframe**.  
Will *not* change the original when **boolean indexing with .loc, `.query()`, or `.copy()` is used to create the new dataframe**

Pandas: Knowing when an operation affects the original dataframe

[Django][1] view points to a function, which can be a problem if you want to change only a bit of functionality. Yes, I could have million keyword arguments and even more if statements in the function, but I was thinking more of an object oriented approach.

For example, I have a page that displays a user. This page is very similar to page that displays a group, but it&#39;s still not so similar to just use another data model. Group also has members etc...

One way would be to point views to class methods and then extend that class. Has anyone tried this approach or has any other idea? 


  [1]: http://www.djangoproject.com/

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