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Run a callback only if an attribute has changed in Rails
...
Rails 5.1+
class Page < ActiveRecord::Base
before_save :do_something, if: :will_save_change_to_status_id?
private
def do_something
# ...
end
end
The commit that changed ActiveRecord::Dirty is here: https://github.com/rails/rails/commit/16ae3db5a5c6a08383b974ae...
What are the differences between a multidimensional array and an array of arrays in C#?
...t32 'value') cil managed
{
// Code size 7 (0x7)
.maxstack 8
IL_0000: ldarg.0
IL_0001: ldarg.1
IL_0002: ldelem.ref
IL_0003: ldarg.2
IL_0004: ldarg.3
IL_0005: stelem.i4
IL_0006: ret
} // end of method Program::SetElementAt
.method private hidebysig static void SetElem...
Can Objective-C switch on NSString?
... @abbood For more information about enum, see the posting NS_ENUM & NS_OPTIONS by Mattt Thompson.
– Basil Bourque
Oct 21 '13 at 21:32
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How to generate an entity-relationship (ER) diagram using Oracle SQL Developer
... is exported. To export in a vector format, use To PDF File, instead. This allows for simplified editing using Inkscape (or other vector image editor).
These instructions may work for SQL Developer 3.2.09.23 to 4.1.3.20.
sh...
What is exactly the base pointer and stack pointer? To what do they point?
Using this example coming from wikipedia, in which DrawSquare() calls DrawLine(),
8 Answers
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How do I remove documents using Node.js Mongoose?
...you don't feel like iterating, try FBFriendModel.find({ id:333 }).remove( callback ); or FBFriendModel.find({ id:333 }).remove().exec();
mongoose.model.find returns a Query, which has a remove function.
Update for Mongoose v5.5.3 - remove() is now deprecated. Use deleteOne(), deleteMany() or findO...
Django admin: How to display a field that is marked as editable=False' in the model?
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+1. Especially if you don't plan to edit the field at all in Admin.
– Manoj Govindan
Oct 19 '10 at 16:05
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iPhone: Detecting user inactivity/idle time since last screen touch
... touch or an Ended touch, to reduce the number of timer resets.
NSSet *allTouches = [event allTouches];
if ([allTouches count] > 0) {
// allTouches count only ever seems to be 1, so anyObject works here.
UITouchPhase phase = ((UITouch *)[allTouches anyObject]).phase;
...
Generate JSON string from NSDictionary in iOS
...ke easier to read).
@interface NSDictionary (BVJSONString)
-(NSString*) bv_jsonStringWithPrettyPrint:(BOOL) prettyPrint;
@end
.
@implementation NSDictionary (BVJSONString)
-(NSString*) bv_jsonStringWithPrettyPrint:(BOOL) prettyPrint {
NSError *error;
NSData *jsonData = [NSJSONSerial...
UICollectionView reloadData not functioning properly in iOS 7
...nd probing. I feel this is an iOS 7 bug. Forcing the main thread will run all UIKit related messages. I seem to run into this when popping to the view from another view controller. I refresh the data on viewWillAppear. I could see the data and collection view reload call, but the UI was not updat...