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How do you query for “is not null” in Mongo?
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This will return all documents with a key called "IMAGE URL", but they may still have a null value.
db.mycollection.find({"IMAGE URL":{$exists:true}});
This will return all documents with both a key called "IMAGE URL" and a no...
android asynctask sending callbacks to ui [duplicate]
I have the following asynctask class which is not inside the activity. In the activity I'm initializing the asynctask, and I want the asynctask to report callbacks back to my activity.
Is it possible? Or does the asynctask must be in the same class file as the activity?
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Sending data back to the Main Activity in Android
...activity.
When I press a button in the main activity, the child activity is launched.
12 Answers
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How to dismiss keyboard for UITextView with return key?
In IB's library, the introduction tells us that when the return key is pressed, the keyboard for UITextView will disappear. But actually the return key can only act as '\n'.
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Possible to iterate backwards through a foreach?
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When working with a list (direct indexing), you cannot do it as efficiently as using a for loop.
Edit: Which generally means, when you are able to use a for loop, it's likely the correct method for this task. Plus, for as much as foreach is impl...
Comments in Markdown
What is the syntax for storing a comment in a markdown file, e.g. a CVS $Id$ comment at the top of the file? I found nothing on the markdown project .
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Hidden features of Perl?
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The flip-flop operator is useful for skipping the first iteration when looping through the records (usually lines) returned by a file handle, without using a flag variable:
while(<$fh>)
{
next if 1..1; # skip first record
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}
Run per...
How do I return multiple values from a function? [closed]
The canonical way to return multiple values in languages that support it is often tupling .
14 Answers
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Generate all permutations of a list without adjacent equal elements
When we sort a list, like
12 Answers
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What RSA key length should I use for my SSL certificates?
I'm in the process of creating a CSR, and I wonder which is arguably the best length for my RSA key.
8 Answers
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