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MongoDB/NoSQL: Keeping Document Change History
... changes to one or more specific entities in a database. I've heard this called row versioning, a log table or a history table (I'm sure there are other names for it). There are a number of ways to approach it in an RDBMS--you can write all changes from all source tables to a single table (more of...
What does `:_*` (colon underscore star) do in Scala?
...tes: MetaData, scope: NamespaceBinding,
child: Node*)
which is called as
new Elem(prefix, label, attributes, scope,
child1, child2, ... childN)
but here there is only a sequence, not child1, child2, etc. so this allows the result sequence to be used as the input to the constru...
MongoDB Many-to-Many Association
... user document:
{name:"Joe"
,roles:["Admin","User","Engineer"]
}
To get all the Engineers, use:
db.things.find( { roles : "Engineer" } );
If you want to maintain the roles in separate documents then you can include the document's _id in the roles array instead of the name:
{name:"Joe"
,roles:...
Getting Java version at runtime
...
Wow, that kind of blew my mind. Though in my case, all I wanted was the first two parts of the version so: Runtime.class.getPackage().getSpecificationVersion()
– Wesley Hartford
Dec 10 '14 at 21:44
...
How to tell if a tag failed to load
I'm dynamically adding <script> tags to a page's <head> , and I'd like to be able to tell whether the loading failed in some way -- a 404, a script error in the loaded script, whatever.
...
Django set default form values
...ch is explained here
You have two options either populate the value when calling form constructor:
form = JournalForm(initial={'tank': 123})
or set the value in the form definition:
tank = forms.IntegerField(widget=forms.HiddenInput(), initial=123)
...
How to increase the vertical split window size in Vim
:vsplit (short form: :vs ) split the Vim viewport vertically. :30vs splits the viewport, making the new window 30 characters wide. Once this 30 char window is created, how would one change it's size to 31 or 29?
...
VIM Disable Automatic Newline At End Of File
So I work in a PHP shop, and we all use different editors, and we all have to work on windows. I use vim, and everyone in the shop keeps complaining that whenever I edit a file there is a newline at the bottom. I've searched around and found that this is a documented behavior of vi & vim... but I w...
Why shouldn't I use mysql_* functions in PHP?
...
The MySQL extension:
Is not under active development
Is officially deprecated as of PHP 5.5 (released June 2013).
Has been removed entirely as of PHP 7.0 (released December 2015)
This means that as of 31 Dec 2018 it does not exist in any supported version of PHP. If you are using a ve...
Finding the index of elements based on a condition using python list comprehension
...
In Python, you wouldn't use indexes for this at all, but just deal with the values—[value for value in a if value > 2]. Usually dealing with indexes means you're not doing something the best way.
If you do need an API similar to Matlab's, you would use numpy, a packag...