I have a table of institutes and a table of locations. I extracted the data from spreadsheets and currently have the following information:
Institute
id, name, ukprn
Location
id, name, ukprn, lat, long, institute
ukprn is the unique id given through the government, but some institutes in the future may not have this so I don't want to specifically use it as a reference. What I think I need to do is for the Location.institute attribute to contain the Institute.id where Institute.ukprn and Location.ukprn match, but I'm not sure how this would work and save it to the code.
I tried:
Location.each do |location|
if location.ukprn == Institute.ukprn then
put Institute.id => Location.institute
end
end
This comes up with an undefined method 'each' error. I'm clearly doing something wrong, but not sure how to go about this.
You are getting undefined method each error because Location as a model class don't have each method. There are other things which are wrong in your code.
You have to do this in a following way,
Institute.find_each do |institute|
Location.where(ukprn: institute.ukprn).update_all(institute_id: institute.id)
end
In above code for each institute you are checking for ukprn corresponding to all locations, every matched location's institute_id will be updated with institute id.
It doesn't make sense to call each method on a class. First get all the locations and institutes and do something like below:
#locations = Location.all
#institutes = Institute.all
#locations.each do |location|
#institutes.each do |institute|
if location.ukprn == institute.ukprn
institute.id = location.institute
institute.save!
end
end
end
I guess there might be a better way to optimize the lookup by not using each to loop over each record, e.g., you can delete/mark a record as "processed" and then later get just get the "unprocessed" records so your array size will reduce in the subsequent each loop.
hope it helps! let me know if you are looking like this.
Related
I've trying to get the simple situation:
I have a Model called Company, inside Company I have companies and I have the following object: "state_id". I want to find the related companies that contain some id.
This is the only path that I can get the state_id. So, I am doing:
Company.all.each do |comp|
comp.address.city.state_id
end
It works! But when I do:
Company.all.each do |comp|
comp.address.city.state_id = 27
#or comp.address.city.state_id(27)
end
it doesn't return the right data
I know that it simple, but unfortunately, I didn't getting the right output.
Thanks a lot!
Try
Company.joins(address: :city).where(cities: {state_id: 27})
You can make it work with select method. Also, don't mix up == and = - the former one checks equality and the latter one assigns a value:
needed_companies = Company.all.select do |comp|
comp.address.city.state_id == 27
end
But it isn't a correct way, because you're loading all companies in memory and filtering it. Much better is to use SQL query (as in answer by Ursus) and return only needed companies from DB
In my rails app I have defined in the Kid model a calculation based on the fields from the Kids DB. the method is as follows:
def flip_date
self.dob.advance(months: 10)
end
I want to use this in my controller as I have a method where I am defining something as follows:
new_kids = Kid.where(discharge_date: nil).where('flip_date > ?', Date.current.advance(year: 1).beginning_of_year)
However I keep getting the following error:
SQLite3::SQLException: no such column: flip_date: SELECT "kids".* FROM "kids" WHERE "kids"."discharge_date" IS NULL AND (flip_date < '2017-01-01')
Any ideas on how can I make this work? All help is appreciated!
If you really want to use model methods take a look at http://apidock.com/rails/v4.0.2/ActiveRecord/QueryMethods/select
For your case:
new_kids = Kid.where(discharge_date: nil).select{|k| k.flip_date > Date.current.advance(year: 1).beginning_of_year}
But select method takes every object in memory before returning final result. Hence I will advise to use normal where clause and instead of flip_date take dob (which is a column in database) in consideration.
Like this
new_kids = Kid.where(discharge_date: nil).where('dob > ?', <date criteria>)
The select method (http://apidock.com/rails/v4.0.2/ActiveRecord/QueryMethods/select) works great if you are okay with the return being an Array.
I am still looking for a way to do this with an ActiveRecord_Relation return.
If others know how to do this, it would be much appreciated if you can share.
This example doesn't respond to your specific code, but to the extent it helps someone else with a similar question, here's a very simple example of how .select can be really handy:
#expired_memberships = User.select{|u| u.membership_expired_yesterday?}
In that example you've looped through all your Users and filtered them based on a custom method you defined on the User model (membership_expired_yesterday?). Now you can easily do stuff with that collection like this example in a mailer:
#expirations.each do |user|
MembershipExpirationMailer.with(user: user).first_reminder.deliver_now
end
I'm a Rails beginner, and have been reading tutorials and typing out applications for a few months now. I'm really enjoying it after a few years spent in the front end world, and beginning to get up to speed with it all. The time has come though for me to start building my own stuff without any handholding. So far, so good.
I'm creating a basic to-do list app, where goals and tasks are displayed on the same page - goals#index. My issue is that I'm not sure how to get all tasks for a particular goal (that belongs to a user). I understand that I need to pass an ID param to the Goal model in order to find out its tasks, like so:
Goal.find(1).tasks
The above works fine, as I've already set up foreign keys on the tasks table and have a has_many :tasks relationship for the Goal model and a belongs_to relationship for the Task model.
Here's my Goals controller:
def index
#user = current_user
#goals = #user.goals # list all goals for the current user and assign it to the #goals variable.
# Need to find all tasks for each goal ID and assign it to the #tasks variable. Goal ID needs to be supplied here, but it isn't as we're not in show action.
#tasks = Goal.find(1).tasks
As I said, I can find all tasks for a Goal when I manually enter the ID (1 in this example). This works fine in my app, no errors. But obviously I want to supply these IDs dynamically, and I'm just not sure how I get the params in there.
I have tried the below:
#tasks = Goal.find(params[:id]).tasks
and
#tasks = Goal.find(params[:goal_id]).tasks
And I get the "Couldn't find Goal without an ID" error when I try to iterate over #tasks in my view. Which makes sense, as I don't think the goal params are being passed to it as we're not in the Show action.
Surely there must be an easy Rails way?! I'm stumped and don't really know where to look. Thanks for your help and Happy New Year.
You are getting current user's goals, so when you will do this you have one array object. so when you will pass array object to find, it will have multiple IDS. so when need to find All the tasks from all goals you just need to pass Array of IDS instead of single value.
#tasks = Task.where(:goal_id => #goals)
This will run this SQL query.
SELECT "tasks".* FROM "tasks" WHERE "tasks"."goal_id" IN (SELECT
"goals"."id" FROM "goals")
So when you are dealing with array just pass ids. for e.g. [1,2,3]
Once you do #goals = #user.goals (assuming that's working, which it sounds like it is), you have your goals and there is no reason to go back to the DB to "find" them.
To get ALL your tasks from ALL of user's goals, you can do the following:
#tasks = []
#goals.each do |goal|
#tasks << goal.tasks
end
Ah of course, #goals is an array of the user's goals so I can just work with that. So simple when someone just tells you. Thanks for all your help!
Here's my final code that works (I left the controller unchanged). This gets the first goal in the array and then gets the tasks associated with each goal. I have a set number of goals so I can just use goals[0], goals[1] or goals[2] for each goal.
<% #goals[0].tasks.each do |task| %>
<li><div class="task-item"><%= task.task_name %></div></li>
<% end %>
I am new in this world of Rails. And I cannot get my head around this problem. How to get #microposts ordered by the date the micropost was created.
This is the line
#microposts = current_user.followeds.map(&:microposts).flatten
I only managed to order by date the 'followeds', but that is not what I am looking for. All the attempts I have made gave me errors, so I guess I am not aware of some syntax.
Any help is welcome!
Normally, you would add an order clause, as in:
Micropost.where(:written_by => current_user.followeds).order(:created_at)
The way you currently have this line structured doesn't permit that, however, since order is only available on ActiveRecord::Relations, and once you do map you no longer have a Relation available to chain on.
If that's the case, you'll want something like:
current_user.followeds.map(&:microposts).flatten.sort_by { |m| m.created_at }
I think you should try to approach this from another angle.
How about something like this:
#microposts = Micropost.where(author_id: current_user.followed_ids).order(:created_at).all
You might of course have to exchange author_id for whatever foreign key you have to identify what user a Micropost was written by.
If you want to reverse the posts (newest first), you just write order("created_at desc") instead.
I write follow code to get one record from the table webeehs:
webeehs_result = Webeeh.find(:all, :conditions=>["webeeh_project_id=#{project_id}"])
Then I want to get one column value from this record, how could I do?
For example, the column name is webeeh_date.
first of all, never EVER write code like that. Building your own conditions as pure strings can leave you vulnerable to SQL injection exploits. If you must do conditions, then do it like this:
:conditions => ["webeeh_project_id = ?", project_id]
if you have a Project model, you should rename the webeeh_project_id column from your Webeeh model into project_id and have an association in your Project model like has_many :webeehs
Then, you won't need to call that find anymore, just do a p = Project.find(id) and then p.webeehs will return the webeehs you need.
the result will be an array which you can iterate through. And to get your webeeh.webeeh_date member, just call it like this:
result.each do |webeeh|
date = webeeh.webeeh_date
end
webeehs_result = Webeeh.findwebeeh_dates
is enough to get all columnn values.
For a different method and performance issues check the following: http://www.stopdropandrew.com/2010/01/28/finding-ids-fast-with-active-record.html
webeeh_result will usually be an array of results for the database.
You can iterate throughit using
webeehs_result.each do |webeeh|
# use "webeeh.webeeh_date" to access the column_name or do whatever you want with it.
end