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mongoDB/mongoose: unique if not null
I was wondering if there is way to force a unique collection entry but only if entry is not null .
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Sample schema:
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Which is best way to define constants in android, either static class, interface or xml resource?
I'm developing an android application which uses web service to get data from server, for that I'm having three different set of URLs to point development system, test server and live server. It's difficult to change URL whenever I want to give application for testing/live. so I planned to make it a...
Why does git perform fast-forward merges by default?
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What is a Manifest in Scala and when do you need it?
Since Scala 2.7.2 there is something called Manifest which is a workaround for Java's type erasure. But how does Manifest work exactly and why / when do you need to use it?
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Build the full path filename in Python
I need to pass a file path name to a module. How do I build the file path from a directory name, base filename, and a file format string?
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How to validate phone numbers using regex
I'm trying to put together a comprehensive regex to validate phone numbers. Ideally it would handle international formats, but it must handle US formats, including the following:
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Which concurrent Queue implementation should I use in Java?
From the JavaDocs:
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Why is rbindlist “better” than rbind?
I am going through documentation of data.table and also noticed from some of the conversations over here on SO that rbindlist is supposed to be better than rbind .
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Java: How to set Precision for double value? [duplicate]
I was working with numbers recently and I had a situation where I want to set the precision of a double value say to 6 digits or 4 digits, depending on the value stored in the database.
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How to create a density plot in matplotlib?
In R I can create the desired output by doing:
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