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Random record from MongoDB
...from a collection using the $sample aggregation pipeline operator:
// Get one random document from the mycoll collection.
db.mycoll.aggregate([{ $sample: { size: 1 } }])
If you want to select the random document(s) from a filtered subset of the collection, prepend a $match stage to the pipeline:
...
using href links inside tag
... to have a drop menu there are plenty of arguably better ways to implement one. This answer is a direct answer to a direct question, but I don't advocate this method for public facing web sites.
UPDATE (May 2020): Someone asked in the comments why I wouldn't advocate this solution. I guess it's a q...
Objective-C: Calling selectors with multiple arguments
...Selectors
- (void) fooNoInputs {
NSLog(@"Does nothing");
}
- (void) fooOneIput:(NSString*) first {
NSLog(@"Logs %@", first);
}
- (void) fooFirstInput:(NSString*) first secondInput:(NSString*) second {
NSLog(@"Logs %@ then %@", first, second);
}
- (void) performMethodsViaSelectors {
[...
Thou shalt not inherit from std::vector
...re using it. What's the difference between std::vector and MyVector? Which one is better to use here and there? What if I need to move std::vector to MyVector? May I just use swap() or not?
Do not produce new entities just to make something to look better. These entities (especially, such common) a...
Thread pooling in C++11
...hreads are created according to Num_Threads, it's better not to create new ones, or destroy old ones (by joining). There will be performance penalty, might even make your application goes slower than the serial version.
Each C++11 thread should be running in their function with an infinite loop, co...
How to change column order in a table using sql query in sql server 2005?
... Both obviously not recommended practices, but SQL Server allows it so someone may have used it somewhere, possibly breaking T-SQL code when changing column order.
– Carvellis
Jul 7 '14 at 13:38
...
Definition of a Balanced Tree
I am just wondering if someone might be able to clarify the definition of a balanced tree for me. I have that "a tree is balanced if each sub-tree is balanced and the height of the two sub-trees differ by at most one.
...
Difference between int32, int, int32_t, int8 and int8_t
...ze can vary (in terms of number of bits) but it's guaranteed to be exactly one byte. One slight oddity though: there's no guarantee about whether a plain char is signed or unsigned (and many compilers can make it either one, depending on a compile-time flag). If you need to ensure its being either s...
Cookie blocked/not saved in IFRAME in Internet Explorer
... it
Create a p3p policy
A good starting point is the W3C tutorial. I've gone through it, downloaded the IBM Privacy Policy Editor and there I created a representation of the privacy policy and gave it a name to reference it by (here it was policy1).
NOTE: at this point, you actually need to find...
What's the difference between lists and tuples?
...er.
Using this distinction makes code more explicit and understandable.
One example would be pairs of page and line number to reference locations in a book, e.g.:
my_location = (42, 11) # page number, line number
You can then use this as a key in a dictionary to store notes on locations. A li...