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What is the colon operator in Ruby?
...bols have the distinct feature that any two symbols named the same will be identical:
"foo".equal? "foo" # false
:foo.equal? :foo # true
This makes comparing two symbols really fast (since only a pointer comparison is involved, as opposed to comparing all the characters like you would in a st...
Can't access object property, even though it shows up in a console log
...ess, but on the very next line of code, I can't access it with config.col_id_3 (see the "undefined" in the screenshot?). Can anyone explain this? I can get access to every other property except field_id_4 as well.
...
SQLAlchemy: What's the difference between flush() and commit()?
...abase until they are committed (if your program aborts for some reason in mid-session transaction, any uncommitted changes within are lost).
The session object registers transaction operations with session.add(), but doesn't yet communicate them to the database until session.flush() is called.
se...
Generate a random number in the range 1 - 10
Since my approach for a test query which I worked on in this question did not work out, I'm trying something else now. Is there a way to tell pg's random() function to get me only numbers between 1 and 10?
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How to select the row with the maximum value in each group
...
A dplyr solution:
library(dplyr)
ID <- c(1,1,1,2,2,2,2,3,3)
Value <- c(2,3,5,2,5,8,17,3,5)
Event <- c(1,1,2,1,2,1,2,2,2)
group <- data.frame(Subject=ID, pt=Value, Event=Event)
group %>%
group_by(Subject) %>%
summarize(max.pt = max(...
MySQL Select all columns from one table and some from another table
....
SELECT table1.*, table2.col1, table2.col3 FROM table1 JOIN table2 USING(id)
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Google OAuth 2 authorization - Error: redirect_uri_mismatch
...m/apis/console I have registered my application, set up generated Client ID: and Client Secret to my app and tried to log in with Google.
Unfortunately, I got the error message:
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@ variables in Ruby on Rails
... and title ? Since both of them can be variable names. Also, how do I decide which kind of variable I should use? With @ or not?
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How to get nice formatting in the Rails console
...rom ruby-docs
In older Ruby versions, ie. <= 1.9, Syck is still provided, however it
was completely removed with the release of Ruby 2.0.0.
For rails 4/ruby 2 you could use just
puts object.to_yaml
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How to bind multiple values to a single WPF TextBlock?
...t;
<Binding Path="Name" />
<Binding Path="ID" />
</MultiBinding>
</TextBlock.Text>
</TextBlock>
Giving Name a value of Foo and ID a value of 1, your output in the TextBlock would then be Foo + 1.
Note: that this is only supported i...