What is the best way to connect to a remote database from Rails just to pull some data? I need to execute a query on the remote server and retrieve the column values. These columns will be the stored locally within a model.
Thanks!
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stackoverflow.com/questions/17311199/…Axel Tetzlaff– Axel Tetzlaff2015-08-19 09:55:56 +00:00Commented Aug 19, 2015 at 9:55
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But that example uses a model. I don't want to use a model, since the remote database is very big, and I only need a few columns from 2 joined tables.H Mihail– H Mihail2015-08-19 10:03:59 +00:00Commented Aug 19, 2015 at 10:03
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I don't see how the number of columns in a table or the size of the overall DB affects the decision of creating models? Creating models does not force you to load the whole DB and also not selecting all columns of a tableAxel Tetzlaff– Axel Tetzlaff2015-08-19 10:11:19 +00:00Commented Aug 19, 2015 at 10:11
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The remote table is already created, and I only need to read some columns. I don't know how to create the model and define the fields, without migration.H Mihail– H Mihail2015-08-19 10:15:34 +00:00Commented Aug 19, 2015 at 10:15
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check solution from this thread: stackoverflow.com/questions/15408285/…greg– greg2015-08-19 10:38:33 +00:00Commented Aug 19, 2015 at 10:38
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1 Answer
For multiple database connection, you need to add the following codes to the database.yml file.
config/database.yml
other_db:
adapter: mysql2
database: db1_dev
username: root
password: xyz
host: localhost
Then create a new model.
class ImportLine < ActiveRecord::Base
establish_connection "other_db"
self.table_name = "the_table_in_th_other_db"
end
Now you can select arbitrary columns like this:
ImportLine.select(:col1, :col2).find_each do |line|
puts "#{line.col1} -#{line.col1}"
end
1 Comment
DemitryT
In case anyone is still using this answer in 2024, it only worked for me when I provided the new db key name as a symbol
establish_connection :other_db. Might be a local issue, but it really didn't like a string value.