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How do I perform the SQL Join equivalent in MongoDB?
...rect. The new $lookup operator added to the aggregation pipeline is essentially identical to a left outer join:
https://docs.mongodb.org/master/reference/operator/aggregation/lookup/#pipe._S_lookup
From the docs:
{
$lookup:
{
from: <collection to join>,
localField: <...
How to implement __iter__(self) for a container object (Python)
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I normally would use a generator function. Each time you use a yield statement, it will add an item to the sequence.
The following will create an iterator that yields five, and then every item in some_list.
def __iter__(self):
...
Dynamically set local variable [duplicate]
How do you dynamically set local variable in Python (where the variable name is dynamic)?
7 Answers
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QString to char* conversion
...t it knowing is a horrible idea, hence of course const char* is what can really be obtained. The user is free to copy the data to a writable buffer.
– Eli Bendersky
Nov 16 '12 at 14:28
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How exactly does __attribute__((constructor)) work?
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It runs when a shared library is loaded, typically during program startup.
That's how all GCC attributes are; presumably to distinguish them from function calls.
GCC-specific syntax.
Yes, this works in C and C++.
No, the function does not need to be static.
The destructo...
How to set environment variables from within package.json
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Just use NPM package cross-env. Super easy. Works on Windows, Linux, and all environments. Notice that you don't use && to move to the next task. You just set the env and then start the next task. Credit to @mikekidder for the suggestion in one of the comments here.
From documentation:
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Reset/remove CSS styles for element only
...ord-spacing : normal;
z-index : auto;
/* basic modern patch */
all: initial;
all: unset;
}
/* basic modern patch */
#reset-this-root {
all: initial;
* {
all: unset;
}
}
Relevent github repo with a december 2017 more exaustive list
Related
Related from MDN
Rel...
Elasticsearch query to return all records
I have a small database in Elasticsearch and for testing purposes would like to pull all records back. I am attempting to use a URL of the form...
...
Why does ReSharper tell me “implicitly captured closure”?
... use.
The compiler generates a class for both lambda expressions and puts all variables in that class which are used in the lambda expressions.
So in my example g and i are held in the same class for execution of my delegates. If g is a heavy object with a lot of resources left behind, the garbage...
Python read-only property
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Generally, Python programs should be written with the assumption that all users are consenting adults, and thus are responsible for using things correctly themselves. However, in the rare instance where it just does not make sens...