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django admin - add custom form fields that are not part of the model
...ite. One of its fields is a long string expression. I'd like to add custom form fields to the add/update page of this model in the admin that based on these fields values I will build the long string expression and save it in the relevant model field.
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Separation of business logic and data access in django
...an find the business logic and entities as perceived by your end user, the former is where you actually store your data.
Furthermore, I've interpreted the 3rd part of your question as: how to notice failure to keep these models separate.
These are two very different concepts and it's always hard to ...
How to pick just one item from a generator?
... next(gen, default) may also be used to avoid the StopIteration exception. For example next(g, None) for a generator of strings will either yield a string or None after the iteration was finished.
– Attila
Mar 6 '13 at 14:18
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What is a proper naming convention for MySQL FKs?
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In MySQL, there is no need to give a symbolic name to foreign key constraints. If a name is not given, InnoDB creates a unique name automatically.
In any case, this is the convention that I use:
fk_[referencing table name]_[referenced table name]_[referencing field name]
Exa...
Understanding slice notation
...d
Python is kind to the programmer if there are fewer items than you ask for. For example, if you ask for a[:-2] and a only contains one element, you get an empty list instead of an error. Sometimes you would prefer the error, so you have to be aware that this may happen.
Relation to slice() obje...
How to update PATH variable permanently from Windows command line?
...ment. Do this by editing the values in HKEY_CURRENT_USER\Environment. As before, make sure that you broadcast a WM_SETTINGCHANGE message.
You should be able to do this from your Java application easily enough using the JNI registry classes.
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Positioning MKMapView to show multiple annotations at once
...tomRightCoord.latitude = 90;
bottomRightCoord.longitude = -180;
for(id<MKAnnotation> annotation in mapView.annotations) {
topLeftCoord.longitude = fmin(topLeftCoord.longitude, annotation.coordinate.longitude);
topLeftCoord.latitude = fmax(topLeftCoord.latitude, ann...
How to print a percentage value in python?
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format supports a percentage floating point precision type:
>>> print "{0:.0%}".format(1./3)
33%
If you don't want integer division, you can import Python3's division from __future__:
>>> from __future__...
Regex to validate password strength
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For anyone who wants a length of at least n, replace .{8} with .{n,}
– NullUserException
Oct 15 '12 at 16:33
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Converting any string into camel case
...ch, index) {
if (+match === 0) return ""; // or if (/\s+/.test(match)) for white spaces
return index === 0 ? match.toLowerCase() : match.toUpperCase();
});
}
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