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Database design for a survey [closed]

...estions. For example: text fields for comments, multiple choice questions, and possibly questions that could contain more than one answer (i.e. check all that apply). ...
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How do I make a textbox that only accepts numbers?

...e past I've done this kind of validation by overloading the KeyPress event and just removing characters which didn't fit the specification. I've looked at the MaskedTextBox control but I'd like a more general solution that could work with perhaps a regular expression, or depend on the values of othe...
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Using vagrant to run virtual machines with desktop environment

...l machines, running on VirtualBox. We would like to move one step further, and use the capabilities of Vagrant to have the description of the machine in a text file and then be able to "raise" that machine based on that text file. Combined to puppet, this would solve us the problem that everyone hav...
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What is Prefix.pch file in Xcode?

...d to make compiling faster. Rather than parsing the same header files over and over, these files get parsed once, ahead of time. Xcode In Xcode, you add imports of the header files you want in a “prefix header,” and enabling Precompile Prefix Header so they get precompiled. But the idea behind a...
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How to communicate between iframe and the parent site?

...bsite in the iframe isn't located in the same domain , but both are mine, and I would like to communicate between the iframe and the parent site. Is it possible? ...
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How do I check if a string contains another string in Objective-C?

..."); } The key is noticing that rangeOfString: returns an NSRange struct, and the documentation says that it returns the struct {NSNotFound, 0} if the "haystack" does not contain the "needle". And if you're on iOS 8 or OS X Yosemite, you can now do: (*NOTE: This WILL crash your app if this code ...
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How do you detect the clearing of a “search” HTML5 input?

... when the user clicks the "x". This is especially useful because it understands the "incremental" attribute. Now, having said that, I'm not sure if you can tell the difference between clicking the "x" and searching, unless you use an "onclick" hack. Either way, hopefully this helps. References: htt...
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How do you serialize a model instance in Django?

... You can easily use a list to wrap the required object and that's all what django serializers need to correctly serialize it, eg.: from django.core import serializers # assuming obj is a model instance serialized_obj = serializers.serialize('json', [ obj, ]) ...
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How is an HTTP POST request made in node.js?

... this were just a small part of the application, you would // want to handle this differently, maybe throwing an exception // for the caller to handle. Since the file is absolutely essential // to the program's functionality, we're going to exit with a fatal // error instead. con...
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Linq: GroupBy, Sum and Count

... I don't understand where the first "result with sample data" is coming from, but the problem in the console app is that you're using SelectMany to look at each item in each group. I think you just want: List<ResultLine> result = Lin...