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django: BooleanField, how to set the default value to true?
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from django.db import models
class Foo(models.Model):
any_field = models.BooleanField(default=True)
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Adding a background image to a element
... like position, attachament
background CSS Property is a connection of all background-xxx propieties in that syntax:
background:
background-color
background-image
background-repeat
background-attachment
background-position;
Source: w3schools
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Dynamic constant assignment
...ject itself is different each time the method is called. For example:
def foo
p "bar".object_id
end
foo #=> 15779172
foo #=> 15779112
Perhaps if you explained your use case—why you want to change the value of a constant in a method—we could help you with a better implementation.
Per...
Why is extending native objects a bad practice?
...ody does it "the wrong way", and adds enumerable types to Object , practically destroying all loops on any object?
8 Answe...
Convert Go map to json
...arshal(datas)
fmt.Println(err)
// [] json: unsupported type: map[int]main.Foo
The thing is you cannot use integers as keys in JSON; it is forbidden. Instead, you can convert these values to strings beforehand, for instance using strconv.Itoa.
See this post for more details: https://stackoverflow...
How do you use the Immediate Window in Visual Studio?
...r example, let’s say this is what your class looks like:
private class Foo
{
public string GetMessage()
{
return "hello";
}
}
If the object already exists in memory and it’s in scope, then you can call it in the Immediate Window as long as it has been instantiated before ...
How does password salt help against a rainbow table attack?
... attack. However, the methods I've seen to implement this don't seem to really make the problem harder.
10 Answers
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No Exception while type casting with a null in java
...ty hence we need to typecast null in these cases:
class A {
public void foo(Long l) {
// do something with l
}
public void foo(String s) {
// do something with s
}
}
new A().foo((String)null);
new A().foo((Long)null);
Otherwise you couldn't call the method you need.
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Understanding Python's “is” operator
What does it really mean?
11 Answers
11
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What's a concise way to check that environment variables are set in a Unix shell script?
...is therefore in the Korn Shell, and in the POSIX shells, including specifically Bash.
It is usually documented in the shell's man page in a section called Parameter Expansion. For example, the bash manual says:
${parameter:?word}
Display Error if Null or Unset. If parameter is null or unset, the...