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django admin - add custom form fields that are not part of the model
...e also given an example of how you might use these values in form.save():
from django import forms
from yourapp.models import YourModel
class YourModelForm(forms.ModelForm):
extra_field = forms.CharField()
def save(self, commit=True):
extra_field = self.cleaned_data.get('extra_f...
Elegant ways to support equivalence (“equality”) in Python classes
...ds of classes:
classic-style (or old-style) classes, that do not inherit from object and that are declared as class A:, class A(): or class A(B): where B is a classic-style class;
new-style classes, that do inherit from object and that are declared as class A(object) or class A(B): where B is a ne...
Why does this CSS margin-top style not work?
... each other because their margins are equal.
Here are the relevant points from the W3C spec:
8.3.1 Collapsing margins
In CSS, the adjoining margins of two or more boxes (which might or might not be siblings) can combine to form a single margin. Margins that combine this way are said to col...
How to open an elevated cmd using command line for Windows?
... same problem and the only way I was able to open the CMD as administrator from CMD was doing the following:
Open CMD
Write powershell -Command "Start-Process cmd -Verb RunAs" and press Enter
A pop-up window will appear asking to open a CMD as administrator
...
Spring Java Config: how do you create a prototype-scoped @Bean with runtime arguments?
... the corresponding @Bean method is also executed.
You can retrieve a bean from the ApplicationContext through its BeanFactory#getBean(String name, Object... args) method which states
Allows for specifying explicit constructor arguments / factory method
arguments, overriding the specified default a...
Is there a way to instantiate a class by name in Java?
I was looking as the question : Instantiate a class from its string name which describes how to instantiate a class when having its name. Is there a way to do it in Java? I will have the package name and class name and I need to be able to create an object having that particular name.
...
What are .a and .so files?
...
.a are static libraries. If you use code stored inside them, it's taken from them and embedded into your own binary. In Visual Studio, these would be .lib files.
.so are dynamic libraries. If you use code stored inside them, it's not taken and embedded into your own binary. Instead it's just ref...
Programmatically set the initial view controller using Storyboards
... storyboard to a different view depending on some condition which may vary from launch to launch.
22 Answers
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Writing to an Excel spreadsheet
I am new to Python. I need to write some data from my program to a spreadsheet. I've searched online and there seem to be many packages available (xlwt, XlsXcessive, openpyxl). Others suggest to write to a .csv file (never used CSV and don't really understand what it is).
...
How to fix “Headers already sent” error in PHP
...k for premature output.
Typical causes:
Print, echo
Intentional output from print and echo statements will terminate
the opportunity to send HTTP headers. The application flow must
be restructured to avoid that. Use functions
and templating schemes. Ensure header() calls occur before messages
ar...