大约有 40,000 项符合查询结果（耗时：0.0518秒） [XML]
Unique BooleanField value in Django?
... save method of the model and if you've set the boolean to True, make sure all others are set to False.
from django.db import transaction
class Character(models.Model):
name = models.CharField(max_length=255)
is_the_chosen_one = models.BooleanField()
def save(self, *args, **kwargs):
...
How to properly reuse connection to Mongodb across NodeJs application and modules
...lhost:27017";
var _db;
module.exports = {
connectToServer: function( callback ) {
MongoClient.connect( url, { useNewUrlParser: true }, function( err, client ) {
_db = client.db('test_db');
return callback( err );
} );
},
getDb: function() {
return _db;
}
};
To...
How do I list the symbols in a .so file
...
Note that readelf -Ws will show you all symbols, and nm -g shows only the externally visible symbols. This may be confusing if you are examining multiple symbol files and start interchanging your commands.
– Andrew B
May 2...
Showing the stack trace from a running Python application
...gdb to the process and get a python stack trace with some gdb macros. Put http://svn.python.org/projects/python/trunk/Misc/gdbinit in ~/.gdbinit, then:
Attach gdb: gdb -p PID
Get the python stack trace: pystack
It's not totally reliable unfortunately, but it works most of the time.
Finally, attac...
Javascript equivalent of Python's zip function
..., unlike Python's version where the argument list is variadic. If you want all of these "features", see below. It takes just about 2 extra lines of code.
The following will mimic Python's zip behavior on edge cases where the arrays are not of equal size, silently pretending the longer parts of arra...
iOS 5 Best Practice (Release/retain?)
...
I am able to get ASIHttpRequest and SBJson working (I get 1 warning on struct usage in Reachability.h). I put the flag in all their implementation files.
– pixelfreak
Jun 24 '11 at 22:37
...
How to find the width of a div using vanilla JavaScript?
...
All Answers are right, but i still want to give some other alternatives that may work.
If you are looking for the assigned width (ignoring padding, margin and so on) you could use.
getComputedStyle(element).width; //returns...
Extract substring in Bash
...o-based) and "5" is the length. Also, +1 for @gontard 's link that lays it all out!
– Doktor J
Sep 12 '14 at 17:32
...
Loop backwards using indices in Python?
... This is better than the accepted answer since it doesn't actually allocate all the numbers in memory (in Python 3 the accepted answer wouldn't either), plus it's more obvious what is happening.
– Blixt
Mar 23 '12 at 13:52
...
Can I use a min-height for table, tr or td?
...n-height: 100px;
}
Table cells will grow when the content does not fit.
https://jsfiddle.net/qz70zps4/
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