Hello I'm looking for a clean way (overide .where method??) to retrieve from DB multiple rows with multiples ids of the same column,
Example:
# Actual ugly mode
args = {}
args[:channel] = common_channel
args[:writer] = userA
args[:receiver] = userB
journalsA = Journal.where args
args[:writer] = userB
args[:receiver] = userA
journalsB = Journal.where args
# #journals = journalsA + journalsB
How can I make something like this: Journals.where userA: userA, userB: userB, channel:x where user(A|B) points to writer and receiver at the same time
Do I need to use a custom SQL line or exist some fancy rails way to do this.
I think you can think of what you are asking as: Can you write a OR query in Rails? The answer is yes, but with SQL fragments:
Journal.where(channel: common_channel).where('(writer = ? AND receiver = ?) OR (writer = ? AND receiver = ?)', userA, userB, userB, userA)
Related
I need to be able to output the SQL UPDATES that would be generated by Rails, without actually running them or Saving the records. I will be outputting the SQL updates to a file instead.
Is there a way to do this in Rails, without using string interpolation?
Is it possible to do something like the following:
p = Post.where (something)
p.some_value = some_new_value
p.to_sql??? # how to generate the update statement
rather than:
"UPDATE TABLE SET field_1 = #{new_field} WHERE ID = " etc etc
Took from #R.F. Nelson and wrap it to a method. You could just calling to_update_sql with your model as the argument to get the SQL.
def to_update_sql(model)
return '' if model.changes.empty?
table = Arel::Table.new(model.class.table_name)
update_manager = Arel::UpdateManager.new(model.class)
update_manager.set(model.changes.map{|name, (_, val)| [table[name], val] })
.where(table[:id].eq(model.id))
.table(table)
return update_manager.to_sql
end
post = Post.first
post.some_value = xxxx
to_update_sql(post)
# => UPDATE `posts` SET `some_value` = xxx WHERE `posts`.`id` = 1
Taken from this post:
You can achieve this goal with AREL:
# Arel::InsertManager
table = Arel::Table.new(:users)
insert_manager = Arel::InsertManager.new
insert_manager.into(table)
insert_manager.insert([ [table[:first_name], 'Eddie'] ])
sql_transaction = insert_manager.to_sql
File.open('file_name.txt', 'w') do |file|
file.write(sql)
end
# Arel::UpdateManager
table = Arel::Table.new(:users)
update_manager = Arel::UpdateManager.new
update_manager.set([[table[:first_name], "Vedder"]]).where(table[:id].eq(1)).table(table)
sql_transaction = update_manager.to_sql
File.open('file_name.txt', 'w') do |file|
file.write(sql)
end
Here you can find all Arel managers, like delete_manager.rb, select_manager.rb and the others.
Good read: http://jpospisil.com/2014/06/16/the-definitive-guide-to-arel-the-sql-manager-for-ruby.html
I have a dashboard that allows for filtering of the results by different parameters. I build methods to filter the results by the given criteria. One area where I'm having trouble is if the previous line should null out the active record relation. Should I just put a bunch of if present? stat
def find_website_stats(options = {})
if options[:date_between].present?
start_date = options[:date_between].split(/-/).first.to_date
end_date = options[:date_between].split(/-/).last.to_date + 1
elsif options[:start_date].present?
start_date = options[:start_date].to_date
end_date = options[:end_date].to_date + 1 if options[:end_date].present?
end
contractor_name = options[:search_contractor] if options[:search_contractor].present?
distributor_name = options[:search_distributor] if options[:search_distributor].present?
distributor_ids = options[:with_distributor] if options[:with_distributor].present?
contractor_ids = options[:with_contractor] if options[:with_contractor].present?
with_country = options[:with_country] if options[:with_country].present?
with_state = options[:with_state] if options[:with_state].present?
search_city = options[:search_city] if options[:search_city].present?
web_stats = self.website_stats
if web_stats.present?
web_stats = web_stats.where(contractor_id: [*contractor_ids]) if contractor_ids.present?
if distributor_ids.present?
web_stat_ids = DistributorWebsiteStat.where(distributor_id: [*distributor_ids]).pluck(:website_stat_id)
web_stats = web_stats.where(id: [*web_stat_ids])
end
web_stats = web_stats.where(date_recorded: start_date..end_date) if start_date.present? && end_date.present?
web_stats = web_stats.with_country(with_country) if with_country.present?
web_stats = web_stats.with_state(with_state) if with_state.present?
web_stats = web_stats.search_city(search_city) if search_city.present?
#untested
if contractor_name.present?
searched_contractor_ids = Brand.search_contractor(contractor_name).pluck(:id)
web_stats = web_stats.where(contractor_id: [*searched_contractor_ids])
end
if distributor_name.present?
searched_distributor_ids = Brand.search_distributor(distributor_name).pluck(:id)
web_stat_ids = DistributorWebsiteStat.where(distributor_id: [*searched_distributor_ids])
web_stats = web_stats.where(id: [*web_stat_ids])
end
#end untested
end
web_stats
end
Where I'm specifically having a problem right now is the line that says if web_stat_ids.present?
So at first I grab all the website stats this object is associated with and then look to see if there are any for the given distributor.
If there is none for the given distributor web_stat_ids obviously returns nil
Then when I go to the line web_stats.where(id: [*web_stat_ids]) that's obviously going to return the same thing that I had before, rather than an empty active record relation, which is what I need it to be?
If I make this an empty array the next few statements with "where" won't work because it's an array and not an active record relation.
I know I can wrap this stuff in a bunch of if present? && statements...but I was wondering if there is a better solution to my problem?
In case anyone else is looking for this, found the answer from this SO post: How to return an empty ActiveRecord relation?
Model.none rails 4+
Assume I have an arbitrary number of Group records and I wanna query User record which has_many :groups, the catch is that users are queries by two bound fields from the groups table.
At the SQL level, I should end up with something like this:
SELECT * FROM users where (categories.id = 1 OR users.status = 0) OR(categories.id = 2 OR users.status = 1) ... -- to infinity
This is an example of what I came up with:
# Doesn't look like a good solution. Just for illustration.
or_query = groups.map do |g|
"(categories.id = #{g.category.id} AND users.status = #{g.user_status.id} )"
end.join('OR')
User.joins(:categories).where(or_query) # Works
What I think I should be doing is something along the lines of this:
# Better?
or_query = groups.map do |g|
"(categories.id = ? AND users.status = ? )".bind(g.category.id, g.user_status.id) #Fake method BTW
end.join('OR')
User.joins(:categories).where(or_query) # Works
How can I achieve this?
There has to be a better way, right?
I'm using Rails 4.2. So the shiny #or operator isn't supported for me.
I would collect the condition parameters separately into an array and pass that array (splatted, i.e. as an arguments list) to the where condition:
or_query_params = []
or_query = groups.map do |g|
or_query_params += [g.category_id, g.user_status.id]
"(categories.id = ? AND users.status = ?)"
end.join(' OR ')
User.joins(:categories).where(or_query, *or_query_params)
Alternatively, you might use ActiveRecord sanitization:
or_query = groups.map do |g|
"(categories.id = #{ActiveRecord::Base.sanitize(g.category_id)} AND users.status = #{ActiveRecord::Base.sanitize(g.user_status.id)})"
end.join(' OR ')
User.joins(:categories).where(or_query)
first_user = User.first
last_user = User.last
How to add two relation object ?
This does not work.
my_users = first_user + last_user
I can use array and push the first and last user.
But pagination will not work for array
users = my_users.paginate# (using will_paginate)
But this works
users = User.limit(2).paginate
This will work, but makes at least three SQL calls:
first_user = User.first
last_user = User.last
users = User.where(id: [first_user.id, last_user.id]).paginate
You cannot add two objects,it should be in array format always then only you can do pagination using will paginate.
you have to follow the below step
user_all = []
first_user = User.first
last_user = User.last
user_all << first_user
user_all << last_user
users = user_all.paginate
I have a Charge model in my database with field names that match up to the fields returned from a third-party API.
charge = ThirdPartyChargeAPI.find(1)
Charge.create do |e|
e.object = charge.object
e.paid = charge.paid
e.amount = charge.amount
e.currency = charge.currency
e.refunded = charge.refunded
e.amount_refunded = charge.amount_refunded
e.failure_message = charge.failure_message
e.failure_code = charge.failure_code
e.description = charge.description
e.metadata = charge.metadata
e.captured = charge.captured
e.balance_transaction = charge.balance_transaction
e.customer = charge.customer
e.invoice = charge.invoice
e.created = charge.created
end
Seems painfully redundant, though. Is there some way to merge this without having to basically set every single field manually?
Assuming there's no way to get a direct hash from the API (I would imagine there would be, since it's probably coming in as XML or JSON), you could try a direct map of instance variables:
Charge.create do |c|
charge.instance_variables.each do |var|
value = charge.instance_variable_get(var)
c.instance_variable_set(var, value)
end
end
This is making some pretty bold assumptions about the structure of the charge you're getting back from the API though - any instance variable in it that you don't want will be included.