I have a users table and a tasks table with a model with the following association:
class Task < ActiveRecord::Base
belongs_to :owner, class_name: User
end
I'm trying to build a query that will search the task's description and its owner's name as such:
includes(:owner).where("LOWER(tasks.description) LIKE ? OR LOWER(owner.name) LIKE ?", "%#{q.downcase}%", "%#{q.downcase}%")
...but I don't know how to properly query the users table for the task owners. In place of owner.name, I've tried users.name, tasks.users.name, and probably a few other things, all to no avail. How can I do this?
Note: I do not want to add a gem for this. I'm looking for a solution that is native to rails.
EDIT:
The foreign key as it exists in my schema.rb
add_foreign_key "tasks", "users", :name => "tasks_owner_id_fk", :column => "owner_id", :dependent => :nullify
SECOND EDIT:
I also need a solution that will return an AREL. I can get this to work by returning an array of objects, but I need to add other query methods to the result, so it has to be AREL.
You need to include a foreign_key of owner_id if you want to call owner.name in your view or query.
Second, you should be able to still call user, but since it's a belongs_to, it would be user.name, not users.name
If you set up the foreign_key you can call owner.name like you did before and it will work.
This should help you set it up:
http://guides.rubyonrails.org/active_record_migrations.html#foreign-keys
After digging around all day, this post helped me out, and my solution is the following:
joins("LEFT OUTER JOIN users ON users.id = tasks.owner_id").where("LOWER(users.name) LIKE ? OR
LOWER(tasks.description) LIKE ?",
"%#{q.downcase}%", "%#{q.downcase}%")
Related
I have two tables, users and couples. The couples table has a pair of foreign keys lead_id and follow_id which point to the users table. I would like for the User class to have a has_many association to Couple which selects all couples in which a given user was a lead or a follow. I can do this using finder_sql and SQL like so:
has_many :couples, class_name: 'Couple', finder_sql:
proc { <<-SQL
SELECT couples.* FROM users
JOIN couples ON (couples.lead_id = users.id
OR couples.follow_id = users.id)
WHERE users.id = #{self.id}
SQL
}
This works fine, but :finder_sql is apparently deprecated, so I'm looking for another way. The best I have gotten is using a custom association scope like this:
has_many :couples, -> {
joins('JOIN couples ON (couples.lead_id = users.id OR couples.follow_id = users.id)')
.select('couples.*')
}, class_name: 'User', foreign_key: 'id'
But this causes ActiveRecord to return User objects rather than Couple objects. Is there a (non-deprecated) way to do this?
Sorry if the title is unclear, I'm open to suggestions.
Looking through the docs (http://guides.rubyonrails.org/association_basics.html) you may be able to get away with just this:
Users model:
has_many: :couples, as: lead
Has_many: :couples, as: follow
Couples model:
belongs_to :users
Also, look at the self joins section if you are attempting to relate leaders and followers.
Hope this helps.
I have the following schema:
Photos has many Groups has many Users.
I am using this Rails server as a backend to an iOS application and constantly need to push out notifications to all involved users of a group when a photo is added.
I problem is finding the least expensive query to resolve only the User.ids affected.
So far I have
Photo.find(1).groups.joins(:users)
I know that I have to put a select argument after this, but can't figure out the syntax for the life of me.
Given a photo, I am looking for the most efficient way to find a collection of the affected user id's.
Any help would be much appreciated!!!
In your Photo model, you can have another associations called users
has_many :group_users, :through => :groups, :source => :users
Then you can find the users by the following code
#photo = Photo.includes([:group_users]).where("photos.id = ?", 1).first
#affected_users = []
#photo.group_users.map {|user| #affected_users << user.id}
Now the #affected_users contains all the user ids.
users_id = []
Group.where(photo_id: 1).users.collect{|u| users_id << u.id}
puts users_id
As Photo has_many groups, so, groups belongs_to photo and groups table has photo_id as foreign key .
So, please try this.
I have the following relationships:
Category has_many :posts
Post has_many :comments
Post has_many :commenters, :through => :comments
I have the following eager load, giving me posts, comments and commenters (note that I need all 3, and hence the includes as opposed to joins)
category.posts.includes(:comments, :commenters)
However, I'd like to limit comments (and if possible commenters) to only those created in the past two weeks while still returning the same set of posts. Initially I thought I could specify a condition on the includes:
category.posts.includes(:comments, :commenters).where("comments.created_at > ?", 2.weeks.ago)
But found that this returns only the posts that meet the condition. I'm thinking that I may need to do something like performing a subquery on comments and then performing a join. Is there an easy way to do this with AR of would I be better off doing this with sql?
Finally managed to figure this out from reading this page:
http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html
I simply needed to create an association in my Post model like:
Post has_many :recent_comments, :class_name = 'Comment', :conditions => ["created_at > ?", 2.weeks.ago]
Then I could do the following to get the desired ActiveRecord::Association object:
category.posts.includes(:recent_comments => :commenters)
There was also a suggestion of doing this by using a scope on a model. However, I read somewhere (I think it was on SO) that scopes are on their way out and that ARel has taken their place so I decided to do this without scopes.
Try :
category.posts.all(:includes => {:comments =>:commenters}, :conditions => ["comments.created_at = ? AND commenters.created_at = ?", 2.weeks.ago, 2.weeks.ago]
I have 3 pertinent models:
class User < ActiveRecord::Base
has_and_belongs_to_many :groups
end
class Group < ActiveRecord::Base
has_and_belongs_to_many :users
has_many :galleries
end
class Gallery < ActiveRecord::Base
belongs_to :group
end
I want to be able to create users and galleries within a group so that only users who are members of the group can view the galleries that belong to that group. I also want users to be able to view galleries of other groups they belong to (hence the HABTM association).
I'm having difficulty in conceptualizing how this works with controllers, and perhaps I'm over thinking the problem. If I create a Group, and then I go to create a user, what is the best way to go about adding the current group_id to the user model? Same thing goes for the gallery model...
Does that make sense?
Let me know if I need to clarify or add code samples.
Thank you very much for your help.
EDIT: Clarification
I definitely didn't make any sense in my initial question, but I did manage to find the answer, with help from a friend.
What I ended up doing is passing the group_id to the form via the params hash like so:
<%= link_to "Add User", new_admin_user_path(:group_id => #group.id) %>
<%= link_to "Add Gallery", new_gallery_path(:group_id => #group.id) %>
Then using a hidden field in my form, assigning the group_id to the "group_id" hidden field:
<%= hidden_field_tag :group_id, params[:group_id] %>
And, finally, in my create methods, adding these lines before the save assigns the group_id perfectly:
# Gallery only has one group
#gallery.group_id = params[:group_id]
# Users can belong to many groups
#user.groups << Group.find(params[:group_id])
I'll still need to sit down and wrap my head around the answers you both provided. Thank you very much for taking the time to help me out. I really appreciate it.
When you are using find method from your controller you can make it like this:
Gallery.find :all, :joins => "INNER JOIN groups ON groups.gallery_id = galleries.id INNER JOIN users ON users.group_id = groups.id", :conditions => "users.id = #{#your_current_user_id}"
It must find all galleries of groups which the user belongs.
I would not define this in the controller as Sebes suggests, but rather in the User model.
Adapting his idea:
def galleries
Gallery.joins(:groups => :users).where("users.id = ?", self.id)
end
Then to get a collection of the galleries for the current_user object:
current_user.galleries
Imagine something like a model User who has many Friends, each of who has many Comments, where I'm trying to display to the user the latest 100 comments by his friends.
Is it possible to draw out the latest 100 in a single SQL query, or am I going to have to use Ruby application logic to parse a bigger list or make multiple queries?
I see two ways of going about this:
starting at User.find and use some complex combination of :join and :limit. This method seems promising, but unfortunately, would return me users and not comments, and once I get those back, I'd have lots of models taking up memory (for each Friend and the User), lots of unnecessary fields being transferred (everything for the User, and everything about the name row for the Friends), and I'd still have to step through somehow to collect and sort all the comments in application logic.
starting at the Comments and using some sort of find_by_sql, but I just can't seem to figure out what I'd need to put in. I don't know how you could have the necessary information to pass in with this to limit it to only looking at comments made by friends.
Edit: I'm having some difficult getting EmFi's solution to work, and would appreciate any insight anyone can provide.
Friends are a cyclic association through a join table.
has_many :friendships
has_many :friends,
:through => :friendships,
:conditions => "status = #{Friendship::FULL}"
This is the error I'm getting in relevant part:
ERROR: column users.user_id does not exist
: SELECT "comments".* FROM "comments" INNER JOIN "users" ON "comments".user_id = "users".id WHERE (("users".user_id = 1) AND ((status = 2)))
When I just enter user.friends, and it works, this is the query it executes:
: SELECT "users".* FROM "users" INNER JOIN "friendships" ON "users".id = "friendships".friend_id WHERE (("friendships".user_id = 1) AND ((status = 2)))
So it seems like it's mangling the :through to have two :through's in one query.
Given the following relationships:
class User < ActiveRecord::Base
has_many :friends
has_many :comments
has_many :friends_comments, :through => :friends, :source => :comments
end
This statement will execute a single SQL statement. Associations essentially create named scopes for you that aren't evaluated until the end of the chain.
#user.friends_comments.find(:limit => 100, :order => 'created_at DESC')
If this is a common query, the find can be simplified into its own scope.
class Comments < ActiveRecord::Base
belongs_to :user
#named_scope was renamed to scope in Rails 3.2. If you're working
#if you're working in a previous version uncomment the following line.
#named_scope :recent, :limit => 100, : order => 'created at DESC'
scope :recent, :limit => 100, :order => 'created_at DESC'
end
So now you can do:
#user.friends_comments.recent
N.B.: The friends association on user may be a cyclical one through a join table, but that's not important to this solution. As long as friends is a working association on User, the preceding will work.