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Test for existence of nested JavaScript object key
...don't want a TypeError because if one of the members is null or undefined, and you try to access a member, an exception will be thrown.
You can either simply catch the exception, or make a function to test the existence of multiple levels, something like this:
function checkNested(obj /*, level1, ...
how to exclude null values in array_agg like in string_agg using postgres?
... non_canonical_users
FROM groups g
GROUP BY g.id
) s
Or, simpler and may be cheaper, using array_to_string which eliminates nulls:
SELECT
g.id,
array_to_string(
array_agg(CASE WHEN g.canonical = 'Y' THEN g.users ELSE NULL END)
, ','
) canonical_users,
array...
“for” vs “each” in Ruby
...r
end
is more idiomatic. While Ruby supports looping constructs like for and while, the block syntax is generally preferred.
Another subtle difference is that any variable you declare within a for loop will be available outside the loop, whereas those within an iterator block are effectively priv...
How to check file MIME type with javascript before upload?
I have read this and this questions which seems to suggest that the file MIME type could be checked using javascript on client side. Now, I understand that the real validation still has to be done on server side. I want to perform a client side checking to avoid unnecessary wastage of server res...
Append column to pandas dataframe
...
@BenDundee Join and concat use a lot of the same code under the hood, so the "right" way probably only matters when you consider edge cases. For instance here if both DataFrames had a 'data' column the join would fail, whereas a concat would...
How do I filter an array with AngularJS and use a property of the filtered object as the ng-model at
If I have an array of objects, and I want to bind the Angular model to a property of one of the elements based on a filter, how do I do that? I can explain better with a concrete example:
...
Is there any pythonic way to combine two dicts (adding values for keys that appear in both)?
...ith them you'd normally do with that type, such as iterate over their keys and values.
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Converting a list to a set changes element order
...at when I am converting a list to set the order of elements is changed and is sorted by character.
11 Answers
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What is a Proxy in Doctrine 2?
... just finished reading all the Doctrine 2 documentation, I started my own sandbox, I understood most of the principes, but there is still a question and I couldn't find any complete explanation in the doc.
...
git replace local version with remote version
How can I tell git to ignore my local file and take the one from my remote branch without trying to merge and causing conflicts?
...