I've got an ActiveRecord class that needs to look at two different tables depending on a configuration switch, so I'm planning to do the following:
def table_name
config_is_on? ? :table1 : :table2
end
I'm wondering whether the table_name method is always called when queries are run against this model: the application is not going to be restarted when the configuration changes, so this value cannot be cached.
Does ActiveRecord always evaluate the table_name or just once during application startup / initialization? If it's cached how do I force it to evaluate table_name every time?
Not only the table name, also the column definition. You'd better go with a schema setup like with the Apartment gem. Depending on some state of a request, the actual table search path in the database is set to something. So you can do two schemas, one with the first table, one with the second (the rest of tables may be on just one schema) and changing the search path you will get different data.
Related
i have Account Model,Asset, Capital and Revenue this table are all inherited in my Account model. i have 3 kind of attributes in my Account model. name, code and type. when i create an account where will be to insert will happen one in my account and the other one is in my type for example
Account.create(name: "test123", code:"test123", type:"Asset")
sql will run Two Insert one for Account model and one for Asset Table
and my sunspot work well it will reindex my database and i can search my params
but when i update my model Account my sql run one insert and one update
my question is how can i reindex my model when i update. with a particular data. i can do Sunspot.reindex but this is will load all data in my sql. that will cause me to slow
sql will run Two Insert one for Account model and one for Asset Table
FYI you use STI when you want to share same database table between multiple models because they are similar in attributes and behavior. Like AdminUser model is likely to have almost same attributes/columns as PublisherUser or ReaderUser. Therefore you might wish to have a common table called users or model User and share this table among the above mentioned models.
Point is: ActiveRecord will run a single SQL query not two, like:
INSERT INTO "accounts" ("name", "code", "type") VALUES ('test123', 'test123', 'Asset')
my question is how can i reindex my model when i update. with a particular data. i can do Sunspot.reindex but this is will load all data in my sql. that will cause me to slow
Actually sunspot_rails is designed to auto-reindex whenever you make changes to your model/record. It listens to the save callbacks.
But you need to make sure that you are not using methods like update_column(s). See the list of silent create/update methods which do not trigger callbacks and validations at all.
In addition, you need to understand the concept of batch size in terms of Solr. For performance reasons, all of your new indexes are not immediately committed. Committed means, writing indexes to database like in RDBMS commits.
By default the batch_size for commits is 50. Meaning after 50 index method executions only the indexes will be committed and you will be able to search the records. To change it, use following
# in config/initializers/sunspot_config.rb
Sunspot.config.indexing.default_batch_size = 1 # or any number
or
# in models; its not considered good though
after_commit do
Sunspot.commit
end
For manual re-indexing, you can use like #Kathryn suggested.
But, I don't think you need to intervene in the auto-operation. I think you were not seeing immediate results so you were worrying.
According to the documentation, objects will be indexed automatically if you are on Rails. But it also mentions you can reindex a class manually:
Account.reindex
Sunspot.commit
It also suggests using Sunspot.index on individual objects.
i put this to my model
after_update do
Sunspot.index Account.where(id: self.id)
end
I am trying to implement a rake task that will run once a month to reset a single column. I would prefer to reset the column to its default value but I cannot find any methods to help me accomplish this. reset_column_information does not work
What is the most efficient way to reset a single column in active record?
Base method #update_all does the update direct in the database, so it is very efficient. However it bypasses callbacks because the models aren't loaded: http://apidock.com/rails/ActiveRecord/Base/update_all/class
SomeModel.update_all("some_column = 4"); # sets all some_column attributes to 4
Resetting it to the default depends on how you are setting the default in the first place. If the default is calculated in the model, then you would have to select and instantiate all the records, which could be very slow. If it's defined in the database, maybe it would be possible but I think it would be database specific.
If you're hardcore you can also drop the column(s) in a migration and then recreate it/them. Sometimes this will be a lot faster. I wouldn't do it in a critical application automatically - but if you're fiddling with your own local machine and just want to test stuff quick, this can be effective.
In my project, i have a situation like when user runs the application.
The system should insert some values in a table which is used allover the application.
(These value should be inserted only once when the project is executed at first time)
I am trying to find out if there is any initialization function like Constructors in Rails.
I tried to use the config/application.rb, but i am not sure its the right way to do this.
Please suggest.
Thanks
If you looking for inserting some default dictionary data like month names etc you should look into seed.rb file or even better consider using seed_fu gem (https://github.com/mbleigh/seed-fu)
Yes you can insert/edit/delete records into table with migration :
1) Create the migration .
2) Run db query inside the execute. like :
execute "insert into users (name, role) values ('vik', 'admin')"
3) After all the insertion operation run the migration.
How if you update have boolean field or any kind of integer field to maintain status in your application. And for the very first time, user runs the application, your code will insert necessary values for that user in db and update boolean/status field and will be cached(for better performance only rather than fetching value from db every time). However after every time cache is cleared, it will send the query to db; but fetching boolean value(checking user status) is more faster than checking all inserted values for that user.
For instance, when I generate an Event model, the table automatically sets to the public schema. How do I specify it to get set to a different schema?
Furthermore, how do you alter the schema of an existing table? Perhaps move it to a different schema?
Thank you!
Disclaimer: I don't know rails, so I'm going to give very postgresql-oriented answers here. For the first part of your question, there is quite possibly a much better way to do this, by making rails specify the schema when creating tables.
In PostgreSQL, tables are searched for in schemas according to the search_path setting. This is set by default to "$user",public. Tables are created in the first schema found in the search path that exists. So if you connect as "my_user", it will try to create tables in "my_user", and fall back to creating them in "public" if "my_user" doesn't exist.
So one approach is to update the "search_path" setting used for the user you connect to the database to make schema changes. For example you can say ALTER USER my_user SET search_path = my_app, public. If you then create a "my_app" schema then subsequent CREATE TABLE foo(...) commands executed by "my_user" will put the new table into "my_app".
You can change the schema of a table using ALTER TABLE foo SET SCHEMA my_app.
Create a migration to generate your new schema. ActiveRecord can't update you schema to you it's the pattern system. You can try sequel or DataMapper if you want update you schema from your code.
I have a standard rails application, that uses a mysql database through Active Record, with data loaded through a separate parsing process from a rather large XML file.
This was all well and good, but now I need to load data from an Oracle database, rather than the XML file.
I have no control how the database looks, and only really need a fraction of the data it contains (maybe one or two columns out of a few tables). As such, what I really want to do is make a call to the database, get data back, and put the data in the appropriate locations in my existing, Rails friendly mysql database.
How would I go about doing this? I've heard* you can (on a model by model basis) specifiy different databases for Rails Models to use, but that sounds like they use them in their entirety, (that is, the database is Rails friendly). Can I make direct Oracle calls? Is there a process that makes this easier? Can Active Record itself handle this?
A toy example:
If I need to know color, price, and location for an Object, then normally I would parse a huge XML file to get this information. Now, with oracle, color, price, and location are all in different tables, indexed by some ID (there isn't actually an "Object" table). I want to pull all this information together into my Rails model.
Edit: Sounds like what I'd heard about was ActiveRecord's "establish_connection" method...and it does indeed seem to assume one model is mapped to one table in the target database, which isn't true in my case.
Edit Edit: Ah, looks like I might be wrong there. "establish_connection" might handle my situation just fine (just gotta get ORACLE working in the first place, and I'll know for sure... If anyone can help, the question is here)
You can create a connection to Oracle directly and then have ActiveRecord execute a raw SQL statement to query your tables (plural). Off the top of my head, something like this:
class OracleModel < ActiveRecord::Base
establish_connection(:oracle_development)
def self.get_objects
self.find_by_sql("SELECT...")
end
end
With this model you can do OracleModel.get_objects which will return a set of records whereby the columns specified in the SELECT SQL statement are attributes of each OracleModel. Obviously you can probably come up with a more meaningful model name than I have!
Create an entry named :oracle_development in your config/database.yml file with your Oracle database connection details.
This may not be exactly what you are looking for, but it seems to cover you situation pretty well: http://pullmonkey.com/2008/4/21/ruby-on-rails-multiple-database-connections/
It looks like you can make an arbitrarily-named database configuration in the the database.yml file, and then have certain models connect to it like so:
class SomeModel < ActiveRecord::Base
establish_connection :arbitrary_database
#other stuff for your model
end
So, the solution would be to make ActiveRecord models for just the tables you want data out of from this other database. Then, if you really want to get into some sql, use ActiveRecord::Base.connection.execute(sql). If you need it as a the actual active_record object, do SomeModel.find_by_sql(sql).
Hope this helps!
I don't have points enough to edit your question, but it sounds like what you really need is to have another "connection pool" available to the second DB -- I don't think Oracle itself will be a problem.
Then, you need to use these alternate connections to "simply" execute a custom query within the appropriate controller method.
If you only need to pull data from your Oracle database, and if you have any ability to add objects to a schema that can see the data you require . . . .
I would simplify things by creating a view on the Oracle table that projects the data you require in a nice friendly shape for ActiveRecord.
This would mean maintaining code to two layers of the application, but I think the gain in clarity on the client-side would outweigh the cost.
You could also use the CREATE OR REPLACE VIEW Object AS SELECT tab1., tab2. FROM tab1,tab2 syntax so the view returned every column in each table.
If you need to Insert or Update changes to your Rails model, then you need to read up on the restrictions for doing Updates through a view.
(Also, you may need to search on getting Oracle to work with Rails as you will potentially need to install the Oracle client software and additional Ruby modules).
Are you talking about an one-time data conversion or some permanent data exchange between your application and the Oracle database? I think you shouldn't involve Rails in. You could just make a SQL query to the Oracle database, extract the data, and then just insert it into the MySQL database.