I am using MySQL and ruby 1.8.6. I want to connect to MySQL so for that I am using active record gem. My code is
def initialize
#db_adapter = "mysql2"
#db_host = "localhost"
#db_database = "database_name"
#db_user = "root"
#db_password = "root123"
con = nil
end
def database_connection
con = ActiveRecord::Base.establish_connection(
:adapter => $db_adapter,
:host => $db_host,
:database => $db_database,
:user => $db_user,
:password => $db_password
)
return con
end
but when i am tring to connect it's giving me this error
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/connection_adapters/abstract/connection_specification.rb:76:in `establish_connection': Please install the adapter: `gem install activerecord--adapter` (no such file to load -- active_record/connection_adapters/_adapter) (RuntimeError)
from /cmf/samnew/build/Controller/databaseConnection.rb:32:in `database_connection'
from controller.rb:23
The error shows the activerecord--adapter gem is not installed. You can install the gem using the command
gem install activerecord--adapter.
Try
con = ActiveRecord::Base.establish_connection(
:adapter => #db_adapter,
:host => #db_host,
:database => #db_database,
:user => #db_user,
:password => #db_password
)
Related
I have included given code in my db.rb file
require "mysql2" # if needed
#db_host = "localhost"
#db_user = "root"
#db_pass = "root"
#db_name = "farji"
client = Mysql::Client.new(:host => #db_host, :username => #db_user, :password => #db_pass, :database => #db_name)
#cdr_result = client.query("SELECT * from employee')
and in terminal i have install
sudo apt-get install libmysqlclient15-dev
gem install mysql2
and run ruby db.rb it gives me error db.rb:8:in `': uninitialized constant Mysql (NameError)
my ruby version is ruby-2.1.5
Please guide me how to solve this.
I need to create a rake task that gets the table rows from a MySQL database, parse the data, and insert into an Oracle database. The databases are on two different hosts.
My current attempt:
namespace :import_from_mysql do
class MySQLConnection < ActiveRecord::Base
self.abstract_class = true
establish_connection({
:adapter => 'mysql',
:host => 'xxx.xxx.com',
:database => 'sample_database',
:username => 'username',
:password => 'password'
})
end
class MySQLTable < MySQLConnection
self.table_name = "users"
self.primary_key = "id"
self.inheritance_column = "something_unique_here"
end
desc "Parse data before inserting to oracle database"
task :insert_to_oracle => :environment do |t|
puts "Rake task has begun...\n\n"
puts "Parsing data from MYSQL...\n\n"
MySQLTable.establish_connection
puts "Rake task has completed!"
end
end
But the MySQLTable.establish_connection establishes a connection to my local database which is sqlite even though I'm trying to connect to a mysql_adapter.
When I tried to establish a connection using the command below, I was able to connect to a MySQL adapter but I don't know how I can access my tables after the connection was established:
ActiveRecord::Base.establish_connection({:adapter => "mysql", :database => "sample_database", :host => "xxx.xxx.com", :username => "username", :password => "password" })
Any idea on why it keeps on connecting to sqlite? And after successfully establishing a connection to mysql, how do I select table rows after the MySQLTable.establish_connection statement?
With the connection generated using ActiveRecord::Base you can execute SQL statements against whatever database you connect to. Like so:
connection = ActiveRecord::Base.establish_connection(
:adapter => "mysql",
:host => "faraway",
:username => "myuser",
:password => "mypass",
:database => "somedatabase"
)
connection.execute('SELECT * FROM users')
Once established, the connection can also be referenced from ActiveRecord::Base class.
ActiveRecord::Base.establish_connection(...)
ActiveRecord::Base.connection.execute(...)
You can use mysql2 gem (https://github.com/brianmario/mysql2) inside your rake task.
client = Mysql2::Client.new(:host => "localhost", :username => "username", :database => "sample_database", :password => "password")
users = client.query("SELECT * FROM users")
Thought it might be helpful for someone else. The following worked for me!
connection = ActiveRecord::Base.establish_connection(
:adapter => "mysql",
:host => "faraway",
:username => "myuser",
:password => "mypass",
:database => "somedatabase"
)
#connection = ActiveRecord::Base.connection
result = #connection.exec_query('SELECT * FROM users')
result.each do |row|
puts row
end
Here, users is an already existing table in the "somedatabase".
although I am a noob with connections and "database back office" my trivial approach works like a charm, and there is no need with parameters in rake task that is for updating "domain tables" that contain only defining data like legal or help texts:
pre_db = ActiveRecord::Base.establish_connection('preproduction').connection
prod_db = ActiveRecord::Base.establish_connection('online').connection
and in database.yml I defined the databases. ("preproduction" is a step between dev and prod in my case and a real environment like "development". where 'online' is almost the same as 'production' (I made a different entry only for security reasons - not to destroy production if database.yml gets uploaded)
I want to add a second read-only database to my application based on a variable aside the SQLite file I'm developing with.
So, there should be three databases.
1. Local SQLite file
2. Production Read-only MySQL database
3. Test Read-only MySQL database
This test database has new columns added and will be pushed as production database soon.
From this SO-Q, I do not understand what the solution is.
I already use establish_connection.
establish_connection(
:adapter => 'mysql2',
:database => "db1",
:username => "username",
:password => "p*ssw*rd",
:host => "ho.st.com"
)
This db1 is the production db without the extra table columns.
db2 is the test db with the extra table columns.
establish_connection(
:adapter => 'mysql2',
:database => "db2",
:username => "username",
:password => "p*ssw*rd",
:host => "ho.st.com"
)
I thought this could be a solution:
In the models of the tables from the MySQL databases:
config = 'test'
case config
when 'test'
establish_connection(
:adapter => 'mysql2',
:database => "db1",
:username => "username",
:password => "p*ssw*rd",
:host => "ho.st.com"
)
else
establish_connection(
:adapter => 'mysql2',
:database => "db2",
:username => "username",
:password => "p*ssw*rd",
:host => "ho.st.com"
)
end
But now I have to edit all 'affected' models when I change the status. Is there a way to variabilise (is that even a word?) this so I only have to edit this config once?
I've tried via Application_controller.rb, but this didn't work.
# Application_controller.rb
def get_config_status
return 'test'
end
# model.rb
config = get_config_status() #=> undefined method `get_config_status' for Regio(Table doesn't exist):Class
# or
config = Application.get_config_status #=> uninitialized constant Regio::Application
Or should I consider totally something else?
To be honest, I don't like putting usernames and passwords in Models. Is this a possible thread for hackers?
Summary
What I'm trying to accomplish is:
Set one variable so my application uses db2 instead of db1.
The octopus gem might be helpful.
https://github.com/tchandy/octopus
You can select the database at query level,
User.where(name: 'Sam').using(:db2)
Or you can select the database per controller action,
class ApplicationController < ActionController::Base
around_filter :select_shard
def select_shard(&block)
Octopus.using(:db1, &block)
end
end
Check out the readme on Github for more examples.
I'm dealing with this a few days, and cannot connect to a simple mysql database on localhost.
require "mysql"
#db_host = "localhost"
#db_user = "myrubyapp"
#db_pass = "1234"
#db_name = "myrubyapp"
mysql = Mysql.new(:host => #db_host, :username => #db_user, :password => #db_pass, :database => #db_name)
The output I got is an error: can't convert Hash into String (TypeError) where Mysql.new is.
The second one, I tried to change the gem to mysql2
require "mysql2"
#db_host = "localhost"
#db_user = "myrubyapp"
#db_pass = "1234"
#db_name = "myrubyapp"
mysql = Mysql2.new(:host => #db_host, :username => #db_user, :password => #db_pass, :database => #db_name)
The output is an error too, but is different from the first: undefined method "new" for Mysql2:Module (NoMethodError).
Guys I'm sorry that I have to ask this kind of questions, but I'm really really confused, I have an experience of programming more than 3 years in JavaSE and EE, I am ashamed cause I can't deal with that. Please point me into right direction and don't judge me harshly. I am new to Ruby.
Try
mysql = Mysql2::Client.new(:host => #db_host, :username => #db_user, :password => #db_pass, :database => #db_name)
correct syntax is:
client = Mysql2::Client.new(:host => "localhost", :username => "root")
see mysql2 on github for more examples
I recomment you to take a look at Sequel as raw mysql2 lib provide a very limited functionality and Sequel can do a lot.
Never used the gem mysql, but have you tried to remove the hash :host => etc and pass directly a list of parameters?
Something like con = Mysql.new db_host, db_user, db_pass, db_name
http://zetcode.com/db/mysqlrubytutorial/ for a tutorial
I have a Rails 3.2 app which use PostgreSQL to store all the information.
But in one Rake task I need to make a connection with the MySQL server. I tried to do this:
ActiveRecord::Base.establish_connection(
:adapter => "mysql2",
:database => "foo",
:user => "root",
:password => "",
)
But it just replace my default PostgreSQL connection with this temporary MySQL.
How to make the additional connection for the instance?
I found a very simple solution: to the the vanila mysql2 gem (https://github.com/brianmario/mysql2)
Now my code looks like:
client = Mysql2::Client.new(:host => "localhost", :username => "root", :database => "foobar", :password => "")
users = client.query("SELECT * FROM users")
After that I have an array of results.
Don't establish it on ActiveRecord::Base.
establish_connection connects to a database from a class, as you've discovered, so when you do it on AR:Base, every subclass of that (to whit, the entire database) has the connection established on it, replacing the current one.
Basically, you create a class for each of the tables you want to connect to, and call the establish connection method in those. If you want to do it in several tables, then create a module with it in and include it.
class MyCustomClass < ActiveRecord::Base
establish_connection(
:adapter => "mysql2",
:database => "foo",
:user => "root",
:password => "",
)
end
MyCustomClass.find(1)