Related
I need to rewrite some DB query so my Rails app can run on Heroku. In one query I need to fetch all entries which are not older then one day. I tried it like this=>
Sendnotifications.where(:actionID => actionID.to_s,
:time => ['? >= time => ?', DateTime.now,DateTime.now-1]).all.count
But this does not work, I guess because of a wrong syntax. So the question is how can I solve this query problem?
Thanks :D
No need to specify two boundaries, one will be more than enough (this way the code will look cleaner):
Sendnotifications.where('time > ?', DateTime.now - 1) #chain all your other methods
Sendnotifications.where(actionID: actionID.to_s)
.where("time between ? and ?", DateTime.now, DateTime.now-1)
.count
I'm hoping there is a easy solution that doesn't involve find_by_sql, if not then I guess that will have to work.
I found this article which references this:
Topic.find(:all, :conditions => { :forum_id => #forums.map(&:id) })
which is the same as
SELECT * FROM topics WHERE forum_id IN (<#forum ids>)
I am wondering if there is a way to do NOT IN with that, like:
SELECT * FROM topics WHERE forum_id NOT IN (<#forum ids>)
Rails 4+:
Article.where.not(title: ['Rails 3', 'Rails 5'])
Rails 3:
Topic.where('id NOT IN (?)', Array.wrap(actions))
Where actions is an array with: [1,2,3,4,5]
FYI, In Rails 4, you can use not syntax:
Article.where.not(title: ['Rails 3', 'Rails 5'])
Using Arel:
topics=Topic.arel_table
Topic.where(topics[:forum_id].not_in(#forum_ids))
or, if preferred:
topics=Topic.arel_table
Topic.where(topics[:forum_id].in(#forum_ids).not)
and since rails 4 on:
topics=Topic.arel_table
Topic.where.not(topics[:forum_id].in(#forum_ids))
Please notice that eventually you do not want the forum_ids to be the ids list, but rather a subquery, if so then you should do something like this before getting the topics:
#forum_ids = Forum.where(/*whatever conditions are desirable*/).select(:id)
in this way you get everything in a single query: something like:
select * from topic
where forum_id in (select id
from forum
where /*whatever conditions are desirable*/)
Also notice that eventually you do not want to do this, but rather a join - what might be more efficient.
You can try something like:
Topic.find(:all, :conditions => ['forum_id not in (?)', #forums.map(&:id)])
You might need to do #forums.map(&:id).join(','). I can't remember if Rails will the argument into a CSV list if it is enumerable.
You could also do this:
# in topic.rb
named_scope :not_in_forums, lambda { |forums| { :conditions => ['forum_id not in (?)', forums.select(&:id).join(',')] }
# in your controller
Topic.not_in_forums(#forums)
To expand on #Trung Lê answer, in Rails 4 you can do the following:
Topic.where.not(forum_id:#forums.map(&:id))
And you could take it a step further.
If you need to first filter for only published Topics and then filter out the ids you don't want, you could do this:
Topic.where(published:true).where.not(forum_id:#forums.map(&:id))
Rails 4 makes it so much easier!
The accepted solution fails if #forums is empty. To workaround this I had to do
Topic.find(:all, :conditions => ['forum_id not in (?)', (#forums.empty? ? '' : #forums.map(&:id))])
Or, if using Rails 3+:
Topic.where( 'forum_id not in (?)', (#forums.empty? ? '' : #forums.map(&:id)) ).all
Most of the answers above should suffice you but if you are doing a lot more of such predicate and complex combinations check out Squeel. You will be able to doing something like:
Topic.where{{forum_id.not_in => #forums.map(&:id)}}
Topic.where{forum_id.not_in #forums.map(&:id)}
Topic.where{forum_id << #forums.map(&:id)}
You may want to have a look at the meta_where plugin by Ernie Miller. Your SQL statement:
SELECT * FROM topics WHERE forum_id NOT IN (<#forum ids>)
...could be expressed like this:
Topic.where(:forum_id.nin => #forum_ids)
Ryan Bates of Railscasts created a nice screencast explaining MetaWhere.
Not sure if this is what you're looking for but to my eyes it certainly looks better than an embedded SQL query.
The original post specifically mentions using numeric IDs, but I came here looking for the syntax for doing a NOT IN with an array of strings.
ActiveRecord will handle that nicely for you too:
Thing.where(['state NOT IN (?)', %w{state1 state2}])
Can these forum ids be worked out in a pragmatic way? e.g. can you find these forums somehow - if that is the case you should do something like
Topic.all(:joins => "left join forums on (forums.id = topics.forum_id and some_condition)", :conditions => "forums.id is null")
Which would be more efficient than doing an SQL not in
This way optimizes for readability, but it's not as efficient in terms of database queries:
# Retrieve all topics, then use array subtraction to
# find the ones not in our list
Topic.all - #forums.map(&:id)
You can use sql in your conditions:
Topic.find(:all, :conditions => [ "forum_id NOT IN (?)", #forums.map(&:id)])
Piggybacking off of jonnii:
Topic.find(:all, :conditions => ['forum_id not in (?)', #forums.pluck(:id)])
using pluck rather than mapping over the elements
found via railsconf 2012 10 things you did not know rails could do
When you query a blank array add "<< 0" to the array in the where block so it doesn't return "NULL" and break the query.
Topic.where('id not in (?)',actions << 0)
If actions could be an empty or blank array.
Here is a more complex "not in" query, using a subquery in rails 4 using squeel. Of course very slow compared to the equivalent sql, but hey, it works.
scope :translations_not_in_english, ->(calmapp_version_id, language_iso_code){
join_to_cavs_tls_arr(calmapp_version_id).
joins_to_tl_arr.
where{ tl1.iso_code == 'en' }.
where{ cavtl1.calmapp_version_id == my{calmapp_version_id}}.
where{ dot_key_code << (Translation.
join_to_cavs_tls_arr(calmapp_version_id).
joins_to_tl_arr.
where{ tl1.iso_code == my{language_iso_code} }.
select{ "dot_key_code" }.all)}
}
The first 2 methods in the scope are other scopes which declare the aliases cavtl1 and tl1. << is the not in operator in squeel.
Hope this helps someone.
If someone want to use two or more conditions, you can do that:
your_array = [1,2,3,4]
your_string = "SOMETHING"
YourModel.where('variable1 NOT IN (?) AND variable2=(?)',Array.wrap(your_array),your_string)
Basically, I have an app with a tagging system and when someone searches for tag 'badger', I want it to return records tagged "badger", "Badger" and "Badgers".
With a single tag I can do this to get the records:
#notes = Tag.find_by_name(params[:tag_name]).notes.order("created_at DESC")
and it works fine. However if I get multiple tags (this is just for upper and lower case - I haven't figured out the 's' bit either yet):
Tag.find(:all, :conditions => [ "lower(name) = ?", 'badger'])
I can't use .notes.order("created_at DESC") because there are multiple results.
So, the question is.... 1) Am I going about this the right way? 2) If so, how do I get all my records back in order?
Any help much appreciated!
One implementation would be to do:
#notes = []
Tag.find(:all, :conditions => [ "lower(name) = ?", 'badger']).each do |tag|
#notes << tag.notes
end
#notes.sort_by {|note| note.created_at}
However you should be aware that this is what is known as an N + 1 query, in that it makes one query in the outer section, and then one query per result. This can be optimized by changing the first query to be:
Tag.find(:all, :conditions => [ "lower(name) = ?", 'badger'], :includes => :notes).each do |tag|
If you are using Rails 3 or above, it can be re-written slightly:
Tag.where("lower(name) = ?", "badger").includes(:notes) do |tag|
Edited
First, get an array of all possible tag names, plural, singular, lower, and upper
tag_name = params[:tag_name].to_s.downcase
possible_tag_names = [tag_name, tag_name.pluralize, tag_name.singularize].uniq
# It's probably faster to search for both lower and capitalized tags than to use the db's `lower` function
possible_tag_names += possible_tag_names.map(&:capitalize)
Are you using a tagging library? I know that some provide a method for querying multiple tags. If you aren't using one of those, you'll need to do some manual SQL joins in your query (assuming you're using a relational db like MySQL, Postgres or SQLite). I'd be happy to assist with that, but I don't know your schema.
I'm hoping there is a easy solution that doesn't involve find_by_sql, if not then I guess that will have to work.
I found this article which references this:
Topic.find(:all, :conditions => { :forum_id => #forums.map(&:id) })
which is the same as
SELECT * FROM topics WHERE forum_id IN (<#forum ids>)
I am wondering if there is a way to do NOT IN with that, like:
SELECT * FROM topics WHERE forum_id NOT IN (<#forum ids>)
Rails 4+:
Article.where.not(title: ['Rails 3', 'Rails 5'])
Rails 3:
Topic.where('id NOT IN (?)', Array.wrap(actions))
Where actions is an array with: [1,2,3,4,5]
FYI, In Rails 4, you can use not syntax:
Article.where.not(title: ['Rails 3', 'Rails 5'])
Using Arel:
topics=Topic.arel_table
Topic.where(topics[:forum_id].not_in(#forum_ids))
or, if preferred:
topics=Topic.arel_table
Topic.where(topics[:forum_id].in(#forum_ids).not)
and since rails 4 on:
topics=Topic.arel_table
Topic.where.not(topics[:forum_id].in(#forum_ids))
Please notice that eventually you do not want the forum_ids to be the ids list, but rather a subquery, if so then you should do something like this before getting the topics:
#forum_ids = Forum.where(/*whatever conditions are desirable*/).select(:id)
in this way you get everything in a single query: something like:
select * from topic
where forum_id in (select id
from forum
where /*whatever conditions are desirable*/)
Also notice that eventually you do not want to do this, but rather a join - what might be more efficient.
You can try something like:
Topic.find(:all, :conditions => ['forum_id not in (?)', #forums.map(&:id)])
You might need to do #forums.map(&:id).join(','). I can't remember if Rails will the argument into a CSV list if it is enumerable.
You could also do this:
# in topic.rb
named_scope :not_in_forums, lambda { |forums| { :conditions => ['forum_id not in (?)', forums.select(&:id).join(',')] }
# in your controller
Topic.not_in_forums(#forums)
To expand on #Trung Lê answer, in Rails 4 you can do the following:
Topic.where.not(forum_id:#forums.map(&:id))
And you could take it a step further.
If you need to first filter for only published Topics and then filter out the ids you don't want, you could do this:
Topic.where(published:true).where.not(forum_id:#forums.map(&:id))
Rails 4 makes it so much easier!
The accepted solution fails if #forums is empty. To workaround this I had to do
Topic.find(:all, :conditions => ['forum_id not in (?)', (#forums.empty? ? '' : #forums.map(&:id))])
Or, if using Rails 3+:
Topic.where( 'forum_id not in (?)', (#forums.empty? ? '' : #forums.map(&:id)) ).all
Most of the answers above should suffice you but if you are doing a lot more of such predicate and complex combinations check out Squeel. You will be able to doing something like:
Topic.where{{forum_id.not_in => #forums.map(&:id)}}
Topic.where{forum_id.not_in #forums.map(&:id)}
Topic.where{forum_id << #forums.map(&:id)}
You may want to have a look at the meta_where plugin by Ernie Miller. Your SQL statement:
SELECT * FROM topics WHERE forum_id NOT IN (<#forum ids>)
...could be expressed like this:
Topic.where(:forum_id.nin => #forum_ids)
Ryan Bates of Railscasts created a nice screencast explaining MetaWhere.
Not sure if this is what you're looking for but to my eyes it certainly looks better than an embedded SQL query.
The original post specifically mentions using numeric IDs, but I came here looking for the syntax for doing a NOT IN with an array of strings.
ActiveRecord will handle that nicely for you too:
Thing.where(['state NOT IN (?)', %w{state1 state2}])
Can these forum ids be worked out in a pragmatic way? e.g. can you find these forums somehow - if that is the case you should do something like
Topic.all(:joins => "left join forums on (forums.id = topics.forum_id and some_condition)", :conditions => "forums.id is null")
Which would be more efficient than doing an SQL not in
This way optimizes for readability, but it's not as efficient in terms of database queries:
# Retrieve all topics, then use array subtraction to
# find the ones not in our list
Topic.all - #forums.map(&:id)
You can use sql in your conditions:
Topic.find(:all, :conditions => [ "forum_id NOT IN (?)", #forums.map(&:id)])
Piggybacking off of jonnii:
Topic.find(:all, :conditions => ['forum_id not in (?)', #forums.pluck(:id)])
using pluck rather than mapping over the elements
found via railsconf 2012 10 things you did not know rails could do
When you query a blank array add "<< 0" to the array in the where block so it doesn't return "NULL" and break the query.
Topic.where('id not in (?)',actions << 0)
If actions could be an empty or blank array.
Here is a more complex "not in" query, using a subquery in rails 4 using squeel. Of course very slow compared to the equivalent sql, but hey, it works.
scope :translations_not_in_english, ->(calmapp_version_id, language_iso_code){
join_to_cavs_tls_arr(calmapp_version_id).
joins_to_tl_arr.
where{ tl1.iso_code == 'en' }.
where{ cavtl1.calmapp_version_id == my{calmapp_version_id}}.
where{ dot_key_code << (Translation.
join_to_cavs_tls_arr(calmapp_version_id).
joins_to_tl_arr.
where{ tl1.iso_code == my{language_iso_code} }.
select{ "dot_key_code" }.all)}
}
The first 2 methods in the scope are other scopes which declare the aliases cavtl1 and tl1. << is the not in operator in squeel.
Hope this helps someone.
If someone want to use two or more conditions, you can do that:
your_array = [1,2,3,4]
your_string = "SOMETHING"
YourModel.where('variable1 NOT IN (?) AND variable2=(?)',Array.wrap(your_array),your_string)
I'm following ryan's Simple Search Form tutorial here:
http://railscasts.com/episodes/37-simple-search-form
I have the following line in my Users Model:
find(:all, :conditions => ['fname LIKE ?', "%#{search}%"])
But what I'd like to do is search across a combine 2 columns,: fname & lname
As users are searching my full names:
Example, James Brown
fname = James
lname = Brown
Is there a way to do this in Rails safely that will work across DBs like SQLite, MySQL or Postgres (heroku uses)?
Thanks!
It may not be pretty, but I use this in my Person model:
scope :by_full_name lambda {|q|
where("first_name LIKE ? or last_name LIKE ? or concat(last_name, ', ', first_name) LIKE ?", "%#{q}%", "%#{q}%" , "%#{q}%")
}
See one of my other posts for an bit extra that will let the search query be optional.
This ended up working extremely well... Not sure about performance though. Can Indexes Help This?
:conditions => ['fname || lname LIKE ?', "%#{search}%"]