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find() with nil when there are no records
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Yes, just do:
Challenge.find_by_id(10)
For Rails 4 and 5:
Challenge.find_by(id: 10)
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What is the best way to do a substring in a batch file?
...s is zero based, so the first character is at position 0, the second at 1, etc.
To get substrings of argument variables such as %0, %1, etc. you have to assign them to a normal environment variable using set first:
:: Does not work:
@echo %1:~10,5
:: Assign argument to local variable first:
set v...
How to create a GUID/UUID using iOS
...tring = CFUUIDCreateString(NULL, theUUID);
CFRelease(theUUID);
return (__bridge NSString *)string;
}
EDIT: Jan, 29 2014:
If you're targeting iOS 6 or later, you can now use the much simpler method:
NSString *UUID = [[NSUUID UUID] UUIDString];
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What are CN, OU, DC in an LDAP search?
...N = Common Name
OU = Organizational Unit
DC = Domain Component
These are all parts of the X.500 Directory Specification, which defines nodes in a LDAP directory.
You can also read up on LDAP data Interchange Format (LDIF), which is an alternate format.
You read it from right to left, the right-m...
Facebook database design?
...d various triggers could fire to cascade events of friending, defriending, etc.
– Jesse C. Slicer
May 14 '12 at 22:05
1
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Property getters and setters
...g to backup the computed property. Try this:
class Point {
private var _x: Int = 0 // _x -> backingX
var x: Int {
set { _x = 2 * newValue }
get { return _x / 2 }
}
}
Specifically, in the Swift REPL:
15> var pt = Point()
pt: Point = {
_x = 0
}
16> pt.x = 10...
iPhone - Grand Central Dispatch main thread
... data on background queue -> signal main queue that message has arrived
etc etc
As to why you might want to dispatch to the main queue from the main queue... Well, you generally wouldn't although conceivably you might do it to schedule some work to do the next time around the run loop.
...
Unique fields that allow nulls in Django
...pty string by providing your own customized model form for Foo with a clean_bar method that turns the empty string into None:
class FooForm(forms.ModelForm):
class Meta:
model = Foo
def clean_bar(self):
return self.cleaned_data['bar'] or None
class FooAdmin(admin.ModelAdmin...
Append TimeStamp to a File Name
... to a file using the Path class and string manipulation is not an issue at all. this only an alternative to DateTime.ToString Method (String) or string.Format("{0:yyyy-MM-dd_hh-mm-ss-tt}",DateTime.Now);
– Joseph
Jun 26 '17 at 11:50
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How can I check if a var is a string in JavaScript?
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Guys, I really would give an accepted answer to both of you, but I can't, all I can do is +1 to both, than give the accepted answer at who is more near to my specific problem, that I've not fully explained.
– vitt...