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Want to find records with no associated records in Rails
...drop the DISTINCT. Otherwise, I think you'd want to normalize out the data and index in that case. I might do that by creating a friend_ids hstore or serialized column. Then you could say Person.where(friend_ids: nil)
– Unixmonkey
Dec 20 '16 at 16:02
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How to randomly pick an element from an array
I am looking for solution to pick number randomly from an integer array.
12 Answers
12...
Ruby Arrays: select(), collect(), and map()
..., but a Hash. You can also use select here, but the block is given the key and value in this case:
irb(main):001:0> h = {:sku=>"507772-B21", :desc=>"HP 1TB 3G SATA 7.2K RPM LFF (3 .", :qty=>"", :qty2=>"1", :price=>"5,204.34 P"}
irb(main):002:0> h.select { |key, value| !value.em...
Cython: “fatal error: numpy/arrayobject.h: No such file or directory”
... You don't need to create a setup.py ... you don't need to even open a command line if you use IPython ... it's all very convenient. In your case, try running these commands in IPython or in a normal Python script:
import numpy
import pyximport
pyximport.install(setup_args={"script_args":["--compil...
select and update database record with a single queryset
How do I run an update and select statements on the same queryset rather than having to do two queries:
- one to select the object
- and one to update the object
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Where does PostgreSQL store the database?
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show data_directory; command points to exact location of data. Searching specific folder is painful as someone else might have installed it for you and now you do not know the configuration, so following sql helps to save the time. :) Thanks Mike.
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Return first match of Ruby regex
I'm looking for a way to perform a regex match on a string in Ruby and have it short-circuit on the first match.
5 Answers
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Resize fields in Django Admin
...g a date field, 8 characters wide, or a CharField, also 6 or 8 chars wide, and then the edit box goes up to 15 or 20 chars.
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What underlies this JavaScript idiom: var self = this?
...his even as the context is changing. It's a technique often used in event handlers (especially in closures).
Edit: Note that using self is now discouraged as window.self exists and has the potential to cause errors if you are not careful.
What you call the variable doesn't particularly matter. va...
Programmatically get height of navigation bar
...ure out if MoreViewController is showing? (If so, what do you want to do?) and if not, could you clarify what exactly you mean?
– Sum
Sep 5 '11 at 22:32
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