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Web-scraping JavaScript page with Python
...a web driver fast enough and easy to get the work done.
Once you have installed Phantom JS, make sure the phantomjs binary is available in the current path:
phantomjs --version
# result:
2.1.1
Example
To give an example, I created a sample page with following HTML code. (link):
<!DOCTYPE ht...
How to get the original value of an attribute in Rails
...
Before rails 5.1
Appending _was to your attribute will give you the previous value.
For rails 5.1+
Copied from Lucas Andrade's answer below: https://stackoverflow.com/a/50973808/9359123
Appending _was is deprecated in rails 5.1, now you should ap...
How to create a directory if it doesn't exist using Node.js?
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using *Sync methods is usually a no-no: don't want to block the event loop
– Max Heiber
Feb 13 '17 at 21:23
16
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How to see the changes between two commits without commits in-between?
...question, so I have no idea why it has so many upvotes. The OP is specifically asking how NOT to get the first command you give, and the second has nothing to do with anything.
– psusi
Sep 4 '15 at 17:51
...
How do I pass extra arguments to a Python decorator?
... it needs to return another function which is the actual decorator:
def my_decorator(param):
def actual_decorator(func):
print("Decorating function {}, with parameter {}".format(func.__name__, param))
return function_wrapper(func) # assume we defined a wrapper somewhere
ret...
How to find where gem files are installed
I can finds gems that are installed using gem list , but it doesn't show me where the gems are installed.
10 Answers
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sqlalchemy unique across multiple columns
... declares those in the table definition, or if using declarative as in the __table_args__:
# version1: table definition
mytable = Table('mytable', meta,
# ...
Column('customer_id', Integer, ForeignKey('customers.customer_id')),
Column('location_code', Unicode(10)),
UniqueConstraint...
Create unique constraint with null columns
...or may not be useful. In extreme situations it might even help to maintain all three indexes (the two partial ones and a total on top).
Aside: I advise not to use mixed case identifiers in PostgreSQL.
share
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How do you remove duplicates from a list whilst preserving order?
...n seen or seen_add(x))]
Why assign seen.add to seen_add instead of just calling seen.add? Python is a dynamic language, and resolving seen.add each iteration is more costly than resolving a local variable. seen.add could have changed between iterations, and the runtime isn't smart enough to rule t...
In PHP, can you instantiate an object and call a method on the same line?
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@CMCDragonkai logically that makes sense; the object only exists for the duration of the statement (new Foo)->property - the value you are storing has nowhere to go because the object will no longer exist after that as it's not stored anywhe...