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How to express a NOT IN query with ActiveRecord/Rails?
.... It would still break on nil, but I find that the array you pass in is usually generated by a filter that will return [] at the very least and never nil. I recommend checking out Squeel, a DSL on top of Active Record. Then you could do: Topic.where{id.not_in actions}, nil/empty/or otherwise.
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How can I center a div within another div? [duplicate]
...ing: 10px;
position: relative;
}
The CSS reference by MDN explains it all.
Check out these links:
auto - CSS reference | MDN
margin - CSS reference | MDN
What is the meaning of auto value in a CSS property - Stack Overflow
In action at jsFiddle.
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Using global variables in a function
...ce global variables are so dangerous, Python wants to make sure that you really know that's what you're playing with by explicitly requiring the global keyword.
See other answers if you want to share a global variable across modules.
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Should the .gradle folder be added to version control?
Gradle creates a folder called .gradle . Should I track it with my version control (i.e. git)?
5 Answers
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Style disabled button with CSS
...he disabled buttons you can use the :disabled pseudo-element. It works for all the elements.
For browsers/devices supporting CSS2 only, you can use the [disabled] selector.
As with the image, don't put an image in the button. Use CSS background-image with background-position and background-repeat....
iPad Web App: Detect Virtual Keyboard Using JavaScript in Safari?
... the size of the user interface to the iPad's window size, the user is normally unable to scroll. In other words, if I set the window's scrollTop, it will remain at 0.
If, on the other hand, the keyboard is shown, scrolling suddenly works. So I can set scrollTop, immediately test its value, and the...
JSON.parse vs. eval()
... and json.parse just parses JSON whereas eval would leave the door open to all JS expressions.
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Reading GHC Core
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GHC Core is the System FC language into which all Haskell is translated. The (approximate) grammar for Core is given by:
Core is closely related to the simpler and better known System F. All transformations GHC does on the Core level are type-preserving refactorings o...
Delegates: Predicate vs. Action vs. Func
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Predicate: essentially Func<T, bool>; asks the question "does the specified argument satisfy the condition represented by the delegate?" Used in things like List.FindAll.
Action: Perform an action given the arguments. Very general purpos...
Javascript How to define multiple variables on a single line?
...; var a = b = c = [];
>>> c.push(1)
[1]
>>> a
[1]
They all refer to the same object in memory, they are not "unique" since anytime you make a reference to an object ( array, object literal, function ) it's passed by reference and not value. So if you change just one of those vari...