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Adding an identity to an existing column
...table_name} alter column {column_name} add generated always as identity (restart with {number});
– Andrew Mackie
Aug 17 '18 at 0:25
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rails - Devise - Handling - devise_error_messages
...ssages.map { |msg| content_tag(:li, msg) }.join
That should help you get started. :)
Another update
The resource object is actually the model that is being used by devise (go figure).
resource.class #=> User
resource.errors.class #=> ActiveModel::Error
It also appears to be de...
mongoDB/mongoose: unique if not null
...he implementation section.
longer version
To supplement @Nolan's answer, starting with MongoDB v3.2 you can use a partial unique index with a filter expression.
The partial filter expression has limitations. It can only include the following:
equality expressions (i.e. field: value or usin...
Which concurrent Queue implementation should I use in Java?
...times one thread will just take several seconds because other threads that started later got processed first). The trade-off is that it takes overhead to manage the fairness, slowing down the throughput.
The most important difference between LinkedBlockingQueue and ConcurrentLinkedQueue is that if ...
How to automatically generate N “distinct” colors?
...essive scale if that's what you want, but when N gets large the colors can start to look similar. I can also imagine evenly subdividing the RGB cube into a lattice and then drawing points. Does anyone know any other methods? I'm ruling out defining a list and then just cycling through it. I should a...
Knight's Shortest Path on Chessboard
...competition, you must know
common algorithms including Dijkstra's.
A good starting point is reading
Introduction to Algorithms ISBN 0-262-03384-4.
Or you could try wikipedia, http://en.wikipedia.org/wiki/List_of_algorithms
...
What is Node.js' Connect, Express and “middleware”?
...ting familiar with developing web apps in Node.js, Express is the place to start. To continue the Ruby analogy, Express is comparable to Sinatra. It's particularly great for creating JSON APIs for Ajax client-side apps. One thing I've found is that once an application hits a certain level of comple...
Confused about stdin, stdout and stderr?
...e file handles totally and open your own files for I/O.
When your process starts, it should already have these handles open and it can just read from and/or write to them.
By default, they're probably connected to your terminal device (e.g., /dev/tty) but shells will allow you to set up connection...
Git merge left HEAD marks in my files
...
Absolutely start with 'git status' to see what you've got. If you aborted a merge (or had a merge aborted) and you've got conflicted files in the working directory then something went wrong. The Git status will tell you where you are....
Build a Basic Python Iterator
...
The __iter__ returns the iterator object and is implicitly called
at the start of loops.
The __next__() method returns the next value and is implicitly called at each loop increment. This method raises a StopIteration exception when there are no more value to return, which is implicitly captured ...