In my app I'm obtaining a certain category, and I'm filtering the associated items based on their name.
The following code should be pretty clear:
categories = Category.where(:id => params[:category_id]).includes(:items).where("lower(items.name) like ?", "%#{params[:keywords].downcase}%")
However, if the name filter excludes all the items, the categories object returned by where is nil. Is this the expected behaviour? How can I get the category even either items exist or not?
The easiest way might be to just split the query:
#category = Category.find(params[:category_id])
#items = #category.items.where("lower(items.name) like ?", "%#{params[:keywords].downcase}%")
Based on your code it seems like category_id references only 1 category so I've changed it to singular.
You should look into doing an OUTER JOIN against the items table which will give you categories regardless of whether or not their items meet the name filter.
Related
So I have a list of sources and have entries. Entries have a field source_id to reference the Source. Now I need to get the count of entries for a number of sources, via the user_id field which is a field in sources.
So basically I need to select all source IDs from a certain user_id and then through those IDs, get a number of entries. I tried the following:
entries_count = Source.where('user_id = ?', user_id).entries.count
But this obviously didn't work.
What would be the way to achieve this?
entries_count = Sources.where('user_id = ?', user_id) will return a collection, not an object. So you have to get each collection element's entries first, and count after:
entries_count = Sources.where('user_id = ?', user_id).map(&:entries).flatten.count
Unrelated thing: is you model really called Sources or it is a typo and it's Source in fact?
I would go from entries to sources using
Entry.joins(:source).where(sources: {user_id: user_id}).count
I have an array #products. Each element of the array is a hash, containing a few fields (but not all) from Product table and the corresponding values.
I have a scope descend_by_popularity in Product which allows me to sort the products based on popularity field. I'd like to sort the array #products using this scope.
What I tried:
#product_group = Array.new
#products.each do |product|
#product_group.push(Product.find(product['id']))
end
#product_group1 = #product_group.descend_by_popularity
But this gives me error:
undefined method `descend_by_popularity' for #<Array:0xb2497200>
I also want to change the sorted Product list back to the format of #products array.
Thanks
Scopes only make sense within the ActiveRecord context for requests to the database (since it is used to change the SQL query). What you did is throwing a lot of products into an array. This array then knows nothing about the scope anymore. You would have to use the scope when you create the #products object. (and it does not seem to make a lot of sense to move the result of a query into an array)
So something like
#products = Product.descend_by_popularity.where(some more stuff)
should work for you. After that you should have the records in the order defined by the scope and can then either use them directly or still push them into an array if that's what you want to do.
With the updated info from the comments it looks like maybe the best way to go would be to first collect only the Product ids from the solr response into an array and then run that as search together with your scope:
#product_group = #products.map{|product| product.id}
#result = Product.where(id: #product_group).descend_by_popularity
this should technically work, peformance is a different question. I would consider aggregating this data into the Solr document, if it doesn't change too often.
Now assuming you are only interested in the order of products as such, you could do something like this to get #products into this order:
#result.map{|r| #products.find{|p| p[:id] == r.id}
though this may slow down things a bit.
Try this: find_by_id as params
#product_group = Array.new
#products.each do |product|
#product_group.push(Product.find(params['id']))
end
and return the array of #product_group
#product_group1 = #product_group.descend_by_popularity
I have two models: Products and Tags through a products_tags join in a HABTM relationship.
I am currently defining my controller index as:
#stats = Product.all(:include => :tags).uniq
which returns an array. How can I return an Active Rel object? I tried added scoped, however received a no method error.
I need to find and list a unique list of tags, and be able to view what product each specif tag belongs to.
Try #stats = Product.includes(:tags).uniq.
Note that uniq turns the Relation into an Array; if you want to do something like SELECT DISTINCT you'll want to use Product.includes(:tags).select('DISTINCT whatever').
I'm using rails and am trying to figure out how to use ActiveRecord within the method to combine the following into one query:
def children_active(segment)
parent_id = Category.select('id').where('segment' => segment)
Category.where('parent_id'=>parent_id, 'active' => true)
end
Basically, I'm trying to get sub categories of a category that is designated by a unique column called segment. Right now, I'm getting the id of the category in the first query, and then using that value for the parent_id in the second query. I've been trying to figure out how to use AR to do a join so that it can be accomplished in just one query.
You can use self join with a alias table name:
Category.joins("LEFT OUTER JOIN categories AS segment_categories on segment_categories.id = categories.parent_id").where("segment_categories.segment = ?", segment).where("categories.active = ?", true)
This may looks not so cool, but it can implement the query in one line, and there will be much less performance loss than your solution when data collection is big, because "INCLUDE IN" is much more slower than "JOIN".
I'll explain this as best as possible. I have a query on user posts:
#selected_posts = Posts.where(:category => "Baseball")
I would like to write the following statement. Here it is in pseudo terms:
User.where(user has a post in #selected_posts)
Keep in mind that I have a many to many relationship setup so post.user is usable.
Any ideas?
/EDIT
#posts_matches = User.includes(#selected_posts).map{ |user|
[user.company_name, user.posts.count, user.username]
}.sort
Basically, I need the above to work so that it uses the users that HAVE posts in selected_posts and not EVERY user we have in our database.
Try this:
user.posts.where("posts.category = ?", "Baseball")
Edit 1:
user.posts.where("posts.id IN (?)", #selected_posts)
Edit 2:
User.select("users.company_name, count(posts.id) userpost_count, user.username").
joins(:posts).
where("posts.id IN (?)", #selected_posts).
order("users.company_name, userpost_count, user.username")
Just use the following:
User.find(#selected_posts.map(&:user_id).uniq)
This takes the user ids from all the selected posts, turns them into an array, and removes any duplicates. Passing an array to user will just find all the users with matching ids. Problem solved.
To combine this with what you showed in your question, you could write:
#posts_matches = User.find(#selected_posts.map(&:user_id).uniq).map{ |user|
[user.company_name, user.posts.size, user.username]
}
Use size to count a relation instead of count because Rails caches the size method and automatically won't look it up more than once. This is better for performance.
Not sure what you were trying to accomplish with Array#sort at the end of your query, but you could always do something like:
#users_with_posts_in_selected = User.find(#selected_posts.map(&:user_id).uniq).order('username DESC')
I don't understand your question but you can pass an array to the where method like this:
where(:id => #selected_posts.map(&:id))
and it will create a SQL query like WHERE id IN (1,2,3,4)
By virtue of your associations your selected posts already have the users:
#selected_posts = Posts.where("posts.category =?", "Baseball")
#users = #selected_posts.collect(&:user);
You'll probably want to remove duplicate users from #users.