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How do you write a migration to rename an ActiveRecord model and its table in Rails?
...e caveats:
Let's use a real-world example I faced today: renaming a model from 'Merchant' to 'Business.'
Don't forget to change the names of dependent tables and models in
the same migration. I changed my Merchant and MerchantStat models to Business and BusinessStat at the same time. Otherwise I'...
cd into directory without having permission
...ou do).
If it is someone else's directory, you'll probably need some help from the owner to change the permissions so that you can access it (or you'll need help from root to change the permissions for you).
share
...
Using ping in c#
... The packet contains a header of 20 bytes which contains the response data from the server which received the ping request. The .Net framework System.Net.NetworkInformation namespace contains a class called PingReply that has properties designed to translate the ICMP response and deliver useful info...
Replacing NAs with latest non-NA value
...
You probably want to use the na.locf() function from the zoo package to carry the last observation forward to replace your NA values.
Here is the beginning of its usage example from the help page:
library(zoo)
az <- zoo(1:6)
bz <- zoo(c(2,NA,1,4,5,2))
na.locf(...
Remote branch is not showing up in “git branch -r”
...tch rules. You could add something like this into it to fetch all branches from the remote:
fetch = +refs/heads/*:refs/remotes/origin/*
(Or replace origin with bitbucket.)
Please read about it here: 10.5 Git Internals - The Refspec
...
List of Java class file format major version numbers?
...
These come from the class version. If you try to load something compiled for java 6 in a java 5 runtime you'll get the error, incompatible class version, got 50, expected 49. Or something like that.
See here in byte offset 7 for more...
Why is rbindlist “better” than rbind?
I am going through documentation of data.table and also noticed from some of the conversations over here on SO that rbindlist is supposed to be better than rbind .
...
How do I add a path to PYTHONPATH in virtualenv
... a path to the PYTHONPATH environment variable, that would be only visible from a particular virtualenv environment.
5 Ans...
Using the slash character in Git branch name
...ven when you call pack-refs, so it’s going out of its way to protect you from this.
– Josh Lee
Mar 27 '10 at 0:37
24
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Providing a default value for an Optional in Swift?
...t need to specify T for the method. That actually overrides the existing T from Optional. You can just do: func getOrElse(defaultValue: T) -> T then T refers to the real value type of the optional and you don't have to type check it
– drewag
Jun 7 '14 at 18:...