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django admin - add custom form fields that are not part of the model
... ModelForm class and then declare your extra fields inside that as you normally would. I've 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.CharFiel...
Why does “_” (underscore) match “-” (hyphen)?
...you are in a pattern context. e.g. inside a LIKE statement. When replacing all _ with an - : UPDATE sys_file set identifier = REPLACE(identifier, '_', '-') WHERE identifier LIKE '%\_%';. Notice the escaping inside LIKE and no escaping inside REPLACE. (I find it strange though that you are not in a p...
Get JSF managed bean by name in any Servlet related class
...ted by JSF beforehand. Else these will return null. You'd then need to manually create the bean and use setAttribute("beanName", bean).
If you're able to use CDI @Named instead of the since JSF 2.3 deprecated @ManagedBean, then it's even more easy, particularly because you don't anymore need to man...
Big-oh vs big-theta [duplicate]
It seems to me like when people talk about algorithm complexity informally, they talk about big-oh. But in formal situations, I often see big-theta with the occasional big-oh thrown in.
I know mathematically what the difference is between the two, but in English, in what situation would using big-oh...
How to debug an apache virtual host configuration?
...d (Ubuntu)
apache2ctl -t
# MacOS
apachectl -t
List virtual hosts
To list all virtual hosts, and their locations:
# Red Hat-based (Fedora, CentOS) and OSX
httpd -S
# Debian-based (Ubuntu)
apache2ctl -S
# MacOS
apachectl -S
...
How to see indexes for a database or table in MySQL?
...fic table use SHOW INDEX:
SHOW INDEX FROM yourtable;
To see indexes for all tables within a specific schema you can use the STATISTICS table from INFORMATION_SCHEMA:
SELECT DISTINCT
TABLE_NAME,
INDEX_NAME
FROM INFORMATION_SCHEMA.STATISTICS
WHERE TABLE_SCHEMA = 'your_schema';
Removing ...
Convert array of strings into a string in Java
...ring();
– Dzarafata
Jun 19 '15 at 7:32
5
Since java 1.8 you can also use String::join, instead of...
How do you run CMD.exe under the Local System Account?
I'm currently running Vista and I would like to manually complete the same operations as my Windows Service. Since the Windows Service is running under the Local System Account, I would like to emulate this same behavior. Basically, I would like to run CMD.EXE under the Local System Account.
...
Compiling problems: cannot find crt1.o
... that's 64bit. You need the 32bit support files. For that, you need to install them
sudo apt install gcc-multilib
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Why would introducing useless MOV instructions speed up a tight loop in x86_64 assembly?
... in the branch prediction table
moving the branch eliminated the alias and allowed the branch to be predicted correctly
Your Core2 doesn't keep a separate history record for each conditional jump. Instead it keeps a shared history of all conditional jumps. One disadvantage of global branch predic...