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Drawing a connecting line between two elements [closed]
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jsPlumb is an option available that supports drag and drop, as seen by its numerous demos, including the Flowchart demo.
It is available in a free Community edition, and a paid Toolkit edition.
The Toolkit edition wraps the Community edition with a comprehensive data bi...
E11000 duplicate key error index in mongodb mongoose
...nt with the sparse index to filter these null values from the unique index and avoid the error.
unique indexes
Sparse indexes only contain entries for documents that have the indexed field, even if the index field contains a null value.
In other words, a sparse index is ok with multiple documents...
What are the rules for calling the superclass constructor?
...bar
}
};
More info on the constructor's initialization list here and here.
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How should I log while using multiprocessing in Python?
...locks so that you don't garble things up in sys.stderr (or whatever filehandle) by having multiple processes writing to it simultaneously.
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How to get .pem file from .key and .crt files?
...ust named with .crt or .key.
If the file's content begins with -----BEGIN and you can read it in a text editor:
The file uses base64, which is readable in ASCII, not binary format. The certificate is already in PEM format. Just change the extension to .pem.
If the file is in binary:
For the serv...
MongoDB and “joins” [duplicate]
...ll only be evaluated when needed. A join (in a SQL database) on the other hand will resolve relationships and return them as if they were a single table (you "join two tables into one").
You can read more about DBRef here:
http://docs.mongodb.org/manual/applications/database-references/
There are ...
Programmatically Lighten or Darken a hex color (or rgb, and blend colors)
...ecific amount. Just pass in a string like "3F6D2A" for the color ( col ) and a base10 integer ( amt ) for the amount to lighten or darken. To darken, pass in a negative number (i.e. -20 ).
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.keyCode vs. .which
... The answer below was written in 2010. Here many years later, both keyCode and which are deprecated in favor of key (for the logical key) and code (for the physical placement of the key). But note that IE doesn't support code, and its support for key is based on an older version of the spec so isn't...
Find running median from a stream of integers
...n left side to represent elements that are less than the effective median, and a min heap on right side to represent elements that are greater than the effective median.
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Checking for an empty field with MySQL
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An empty field can be either an empty string or a NULL.
To handle both, use:
email > ''
which can benefit from the range access if you have lots of empty email record (both types) in your table.
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