This gem allows you to extend models without migrations: This way you can, i.e., develop your own content types, like in Drupal.
For example, if you want to create an administration panel to add columns to a model, for example, you are working on a CMS, and you want to create a "content type" and you need to set the "columns" but you don't want to migrate the database, then, you can see this little tutorial.
gem install extend_at
Add in your Gemfile:
gem 'extend_at'
After that, you need execute:
rails generate extend_at:install
This will generate one migration with all necessary tables. Now you need migrate your database.
rake db:migrate
You don't need an extra column in your model. Only you need is put next code in your model.
extend_at :extra
For example:
class User < ActiveRecord::Base
extend_at :extra
end
Now you can create extra attributes:
user.extra.private_photos = true
user.extra.subscribe_to_news = false
user.extra.profile_description = ''
user.save
This is the same:
user.extra_private_photos = true
user.extra_subscribe_to_news = false
user.extra_profile_description = ''
user.save
Or:
user[:extra_private_photos] = true
user[:extra_subscribe_to_news] = false
user[:extra_profile_description] = ''
user.save
You can configure each column.
You can set the colum's type.
class User < ActiveRecord::Base
extend_at :extra, :columns => {
:private_photos => {
:type => :boolean
}, :age => {
:type => :get_type
}, :profile_description => {
:type => lambda {
String
}
}, :last_loggin => {
:type => Time.now.class
}, :subscribe_to_rss => :get_rss_config
}
protected
def get_type
Fixnum
end
def get_rss_config
{
:type => :boolean
}
end
end
Valid symbols:
:any:binary:boolean:date:datetime:decimal:float:integer:string:text:time:timestamp
But you can use classes.
- Float:
:any - Fixnum:
:integer - String:
:text - Time:
:timestamp - Date:
:datetime
Else, return :any
class User < ActiveRecord::Base
extend_at :extra, :columns => {
:private_photos => {
:type => :boolean,
:default => true
}, :age => {
:type => :get_type,
:default => 1
}, :profile_description => {
:type => lambda {
String
},
:default => :get_default_profile_description
}, :last_loggin => {
:type => Time.now.class,
:default => lambda {
self.created_at.time
}
}, :subscribe_to_rss => :get_rss_config
}
protected
def get_type
Fixnum
end
def get_rss_config
{
:type => :boolean,
:default => true
}
end
def get_default_profile_description
Description.where(:user_id => self.id).default
end
end
class User < ActiveRecord::Base
extend_at :extra, :columns => {
:private_photos => {
:type => :boolean,
:default => true
}, :age => {
:type => :get_type,
:default => 1,
:validate => lambda {
|age|
errors.add :extra_age, "Are you Matusalen?" if age > 150
errors.add :extra_age, "Are you a fetus?" if age <= 0
}
}, :profile_description => {
:type => lambda {
String
},
:default => :get_default_profile_description,
:lambda => :must_not_use_strong_language
}, :last_loggin => {
:type => Time.now.class,
:default => lambda {
self.created_at.time
},
:validate => lambda {
|time|
errors.add :extra_last_loggin, "You can't loggin on the future" if time > Time.now
}
}, :subscribe_to_rss => :get_rss_config
}
protected
STRONG_WORD = [
#...
]
def get_type
Fixnum
end
def get_rss_config
{
:type => :boolean,
:default => true
}
end
def get_default_profile_description
Description.where(:user_id => self.id).default
end
def must_not_use_strong_language(desc)
errors.add :cofig_profile_description, "You must not use strong language" if desc =~ /(#{STRONG_WORD.join('|')})/
end
end
If you like to restrict the existent extended columns, you should use :static => true
class User < ActiveRecord::Base
extend_at :extra, :columns => {
:private_photos => {
:type => :boolean,
:default => true
}
}, :static => true
end
Now, User.extra only accept private_photos column
You can use scope like:
User.extra_last_loggin_gt_eq(1.week.ago).extra_age_gt_eq(18).where(:column => "value").all
Valid scopes:
<extention>_<column_name>_<comparation>
Comparations:
- lt
- lt_eq
- eq
- gt_eq
- gt
- match
If you like to add a belongs_to relationship, you can do it in this way:
# app/models/toolbox.rb
class Toolbox
end
# app/model/tool.rb
class Tool
extend_at extra, columns => {}, :belongs_to => :toolbox
end
:belongs_to parametter accept
-
One name
:belongs_to => :toolbox
-
Array of names
:belongs_to => [:toolbox, :owner]
-
Hash
:belongs_to => {:onwer => {:class_name => "User"}}
For now, hash only accept
- class_name
- polymorphic
- foreign_key
Note, this new feature is under heavy development, use it under your own risk.
If you like to use some configuration variable in your views you only need put the name of the input like :extra_name, for example:
<% form_for(@user) do |f| %>
...
<div class="field">
<%= f.label :extra_private_photos %><br />
<%= f.check_box :extra_private_photos %>
</div>
...
<% end %>
For more documentation go to wiki.
If you like to do something more dynamic, like create columns and validations depending of some model or configuration, then you can do something like this:
class User < ActiveRecord::Base
extend_at :extra, :columns => :get_columns
serialize :columns_name
protected
def get_columns
columns = {}
columns_name.each do |name|
config = ColumConfig.where(:user_id => self.id, :column => name).first
columns[name.to_sym] = {
:type => eval(config.class_type),
:default => config.default_value,
:validate => get_validation(config)
}
end
columns
end
# Accept a name of a validation and return the Proc with the validation code
def get_validation(validation_type)
# ...
end
end
How works?
serialize :columns_name
This make columns_name column work like YAML serialized object. In this case, is used to sotore an array of names of each column name.
(See ActiveRecord::Base)
extend_at :extra, :columns => :get_columns
This line will use the function get_columns to get the information about each column dynamically.
This function returns a hash with the information about each column.
columns_name.each do |name|
#...
end
Iterate through each column stored in the column columns_name.
config = ColumConfig.where(:user_id => self.id, :column => name).first
Search the column configuration stored in a separated model. By this way, we can configura each column easily, we can create a view to create columns and configure it easily.
columns[name.to_sym] = {
:type => eval(config.class_type),
:default => config.default_value,
:validate => get_validation(config)
}
This lines configure the column.
:type => eval(config.class_type),
The model ColumConfig have a string column named class_type, can be ":integer" or "Fixnum".
:default => config.default_value,
The model ColumConfig have a serialized column named default_valuee, in this way we can sotre integer values, boolean, strings or datetime and time values without problems.
:validate => get_validation(config.validation)
This line execute the function get_validation to get a Proc with the validation code.
This function can use a case/when for select the correct function or use the data of the model config to create a function.
columns
Finally we return the colums configuration.
If you found a bug, create an issue. If you have a recomendation, idea, etc., create a request or fork the project.
This gem is under MIT license.