This issue is slightly complex so here is a bit of background:
I’m developing a wrapper that allows you to easily integrate extjs with
rails. At the moment i’m developing with the “grid widget”.
The point of the widget is to allow the user a customizable sortable,
filterable, paginated grid that works with relationships with the
minimum of setup.
To set one of these grids up you follow the steps:
a) Setup a configuration yaml file which defines a “base model” to work
with, followed by all the “columns” to be displayed in the grid using
the relationship path from the base model to define where to fetch the
data from.
employee_addresses:
model: Person
store:
- gender
- birthday
- age
- email
- home_address.street_no
- home_address.street_name
- home_address.street_type
- home_address.suburb.name
- home_address.suburb.post_code
- work_address.suburb.name
b) In the controller you simply perform a search applying security
conditions etc, create a Grid object, and pass that to a view helper
which sets up the html and javascript. (note at this stage, the
named_filter filter does not do anything when first viewing, it only
filters after filter conditions start coming in via xhr)
def myaction
people = Person.filter(‘employee_addresses’,
params[:filter]).find(:all,
:include => [{:home_address =>
:suburb},{:work_address => :suburb}],
:conditions => ‘some_extra_security_stuff’,
:limit => 10)
@grid = Grid.new(:name => ‘employee_addresses’,
:collection => people)
respond_to do |format|
format.html { render :action => :grid_model_test }
format.json do
render :text => @grid.data.to_json
end
end
end
end
c) The user then using the js interface selects some filtering
conditions and this gets passed via params into the controller in the
form something like
field_type: string
field_name: home_address.suburb.name
conditions: equal
value: my_home_suburb
This then gets passed into the filter in which i have to construct the
appropriate sql conditions.
The issue I have been struggling over is that I can not predict what the
table name will be aliased by activerecord. I have to be able to convert
‘home_address.suburb.name’ into suburb.name. but in some cases it
activerecord aliases that to suburbs_addresses.name.
From what I can tell, the first time the relationship is used it uses
“suburbs” with no alias, then “suburbs_addresses”. But in another field
i’ve noticed that it’s used the relationship name
“home_addresses_people”.
Here is an example of the generated sql:
FROM people
LEFT OUTER JOIN addresses ON addresses.id =
people.work_address_id
LEFT OUTER JOIN suburbs ON suburbs.id =
addresses.suburb_id
LEFT OUTER JOIN addresses home_addresses_people ON
home_addresses_people.id = people.home_address_id
LEFT OUTER JOIN suburbs suburbs_addresses ON
suburbs_addresses.id = home_addresses_people.suburb_id
WHERE (home_address.suburb.suburb like ‘my_home_suburb’)
Is there anyway I can make the aliasing of the tables predictable? …
i.e I know that it will always use a specific alias
One solution i have considered (although it’s a little extreme, and
might break apps using the plugin) is to force active record to alias
all fields based on their relationships. i.e.
suburbs would become home_address_suburb, work_address_suburb etc
Any help will be greatly appreciated as i’ve been struggling with this
issue, i’ve already got a fully working solution that works without
filtering