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Mongoose query where value is not null
...o list the profiles where user ref is not null (because I already filtered by rol during the population), but
after googleing a few hours I cannot figure out how to get this. I
have this query:
const profiles = await Profile.find({ user: {$exists: true, $ne: null }})
...
Handling applicationDidBecomeActive - “How can a view controller respond to the app becoming Active?
...tionDidBecomeActiveNotification and specify which method that you want to call when that notification gets sent to your application.
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(someMethod:)
...
How to set a Django model field's default value to a function call / callable (e.g., a date relative
... to create a field in the class.
PRE Django 1.7
Django lets you pass a callable as the default, and it will invoke it each time, just as you want:
from datetime import datetime, timedelta
class MyModel(models.Model):
# default to 1 day from now
my_date = models.DateTimeField(default=lambda: ...
Rails - Nested includes on Active Records?
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how to add there a order?
– Florian Widtmann
Jan 12 '16 at 7:49
6
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Create singleton using GCD's dispatch_once in Objective-C
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@WalterMartinVargas-Pena the strong reference is held by the static variable
– Dave DeLong
Nov 15 '13 at 0:42
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show 3 ...
SQL JOIN and different types of JOINs
... a.actor_id -- JOIN predicate with the outer query!
GROUP BY f.film_id
ORDER BY revenue DESC
LIMIT 5
) AS f
ON true
It will find the TOP 5 revenue producing films per actor. Every time you need a TOP-N-per-something query, LATERAL JOIN will be your friend. If you're a SQL Server person, then...
Ruby on Rails - Import Data from a CSV file
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The smarter_csv gem was specifically created for this use-case: to read data from CSV file and quickly create database entries.
require 'smarter_csv'
options = {}
SmarterCSV.process('input_file.csv', options) do |chunk|
chunk.each do |data_hash|
...
select and update database record with a single queryset
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@learning well dude, it all depends on your scenario. The update method is great for mass updates, but it should set off a warning in your head when you use it that you need to review any signals attached to that object that might also need to be m...
AWS: How to disable all services?
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Random Gaussian Variables
...s the fastest approach. Furthermore the above approach can be made faster by carrying a value from one call to the next.
– Drew Noakes
Jan 4 '11 at 14:49
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