my problem should be rather simple, but i didn't got it.
For example i have the following data from the database:
#user = User.all
then i have an other array of user
other_user = getting_them_from_somewhere_else
Now i iterate over the two arrays and check if some users are still in the database by checking for the emails:
#other_user.each do |o|
#user.each do |u|
if o["email"] == u["user_mail"]
#user.delete(u)
break
end
end
... do something with o ...
end
The method #user.delete(u) deletes the user from the database, but i just want to remove the object u from the array #user.
You can do vise versa
result_users = []
#other_user.each do |o|
#user.each do |u|
if o["email"] != u["user_mail"]
result_users << u
end
end
... do something with o ...
end
here you should use result_users array which has the users you need
You can use:
#other_user.each do |o|
#user.delete_if{|u| u["email"] == o["email"]}
end
It's more simple, and didn't remove of database, only remove in array. =)
How about going the cheaper way... Less work..
create an array of the email addresses that you know about, and don't want anymore.
other_emails = #other_user.map{|o| sanitize(o["email"]) }
#users = User.where("email not in ( #{other_emails.join(',')} )")
There are so many pluses to this approach.
there is only one loop (the map), nothing embedded.
there is only one array resize (the map). We aren't calling delete which is a heavy operation on an array.
We only get records across the network that we care about. Pulling down 1 million records when you only care about a handful is silly. Strive to only read from the DB what you need.
Sometimes letting the database do things is just smarter.
I think you don't need to use #user.email, just:
#users.delete_if {|user| #other_user.include? user}
Related
I need to compare the 2 arrays declared here to return records that exist only in the filtered_apps array. I am using the contents of previous_apps array to see if an ID in the record exists in filtered_apps array. I will be outputting the results to a CSV and displaying records that exist in both arrays to the console.
My question is this: How do I get the records that only exist in filtered_apps? Easiest for me would be to put those unique records into a new array to work with on the csv.
start_date = Date.parse("2022-02-05")
end_date = Date.parse("2022-05-17")
valid_year = start_date.year
dupe_apps = []
uniq_apps = []
# Finding applications that meet my criteria:
filtered_apps = FinancialAssistance::Application.where(
:is_requesting_info_in_mail => true,
:aasm_state => "determined",
:submitted_at => {
"$exists" => true,
"$gte" => start_date,
"$lte" => end_date })
# Finding applications that I want to compare against filtered_apps
previous_apps = FinancialAssistance::Application.where(
is_requesting_info_in_mail: true,
:submitted_at => {
"$exists" => true,
"$gte" => valid_year })
# I'm using this to pull the ID that I'm using for comparison just to make the comparison lighter by only storing the family_id
previous_apps.each do |y|
previous_apps_array << y.family_id
end
# This is where I'm doing my comparison and it is not working.
filtered_apps.each do |app|
if app.family_id.in?(previous_apps_array) == false
then #non_dupe_apps << app
else "No duplicate found for application #{app.hbx_id}"
end
end
end
So what am I doing wrong in the last code section?
Let's check your original method first (I fixed the indentation to make it clearer). There's quite a few issues with it:
filtered_apps.each do |app|
if app.family_id.in?(previous_apps_array) == false
# Where is "#non_dupe_apps" declared? It isn't anywhere in your example...
# Also, "then" is not necessary unless you want a one-line if-statement
then #non_dupe_apps << app
# This doesn't do anything, it's just a string
# You need to use "p" or "puts" to output something to the console
# Note that the "else" is also only triggered when duplicates WERE found...
else "No duplicate found for application #{app.hbx_id}"
end # Extra "end" here, this will mess things up
end
end
Also, you haven't declared previous_apps_array anywhere in your example, you just start adding to it out of nowhere.
Getting the difference between 2 arrays is dead easy in Ruby: just use -!
uniq_apps = filtered_apps - previous_apps
You can also do this with ActiveRecord results, since they are just arrays of ActiveRecord objects. However, this doesn't help if you specifically need to compare results using the family_id column.
TIP: Getting the values of only a specific column/columns from your database is probably best done with the pluck or select method if you don't need to store any other data about those objects. With pluck, you only get an array of values in the result, not the full objects. select works a bit differently and returns ActiveRecord objects, but filters out everything but the selected columns. select is usually better in nested queries, since it doesn't trigger a separate query when used as a part of another query, while pluck always triggers one.
# Querying straight from the database
# This is what I would recommend, but it doesn't print the values of duplicates
uniq_apps = filtered_apps.where.not(family_id: previous_apps.select(:family_id))
I highly recommend getting really familiar with at least filter/select, and map out of the basic array methods. They make things like this way easier. The Ruby docs are a great place to learn about them and others. A very simple example of doing a similar thing to what you explained in your question with filter/select on 2 arrays would be something like this:
arr = [1, 2, 3]
full_arr = [1, 2, 3, 4, 5]
unique_numbers = full_arr.filter do |num|
if arr.include?(num)
puts "Duplicates were found for #{num}"
false
else
true
end
end
# Duplicates were found for 1
# Duplicates were found for 2
# Duplicates were found for 3
=> [4, 5]
NOTE: The OP is working with ruby 2.5.9, where filter is not yet available as an array method (it was introduced in 2.6.3). However, filter is just an alias for select, which can be found on earlier versions of Ruby, so they can be used interchangeably. Personally, I prefer using filter because, as seen above, select is already used in other methods, and filter is also the more common term in other programming languages I usually work with. Of course when both are available, it doesn't really matter which one you use, as long as you keep it consistent.
EDIT: My last answer did, in fact, not work.
Here is the code all nice and working.
It turns out the issue was that when comparing family_id from the set of records I forgot that the looped record was a part of the set, so it would return it, too. I added a check for the ID of the array to match the looped record and bob's your uncle.
I added the pass and reject arrays so I could check my work instead of downloading a csv every time. Leaving them in mostly because I'm scared to change anything else.
start_date = Date.parse(date_from)
end_date = Date.parse(date_to)
valid_year = start_date.year
date_range = (start_date)..(end_date)
comparison_apps = FinancialAssistance::Application.by_year(start_date.year).where(
aasm_state:'determined',
is_requesting_voter_registration_application_in_mail:true)
apps = FinancialAssistance::Application.where(
:is_requesting_voter_registration_application_in_mail => true,
:submitted_at => date_range).uniq{ |n| n.family_id}
#pass_array = []
#reject_array = []
apps.each do |app|
family = app.family
app_id = app.id
previous_apps = comparison_apps.where(family_id:family.id,:id.ne => app.id)
if previous_apps.count > 0
#reject_array << app
puts "\e[32mApplicant hbx id \e[31m#{app.primary_applicant.person_hbx_id}\e[32m in family ID \e[31m#{family.id}\e[32m has registered to vote in a previous application.\e[0m"
else
<csv fields here>
csv << [csv fields here]
end
end
Basically, I pulled the applications into the app variable array, then filtered them by the family_id field in each record.
I had to do this because the issue at the bottom of everything was that there were records present in app that were themselves duplicates, only submitted a few days apart. Since I went on the assumption that the initial app array would be all unique, I thought the duplicates that were included were due to the rest of the code not filtering correctly.
I then use the uniq_apps array to filter through and look for matches in uniq_apps.each do, and when it finds a duplicate, it adds it to the previous_applications array inside the loop. Since this array resets each go-round, if it ever has more than 0 records in it, the app gets called out as being submitted already. Otherwise, it goes to my csv report.
Thanks for the help on this, it really got my brain thinking in another direction that I needed to. It also helped improve the code even though the issue was at the very beginning.
I am using active record to create array.
users = User.all.to_a
now I want to later on find with in this array user id: 1
users.find(1)
but it is not giving result but returning everything. How can I search in this result array my selected user id. I can see users is a an array but with in array each record of User object.
If I do following
user.first
it return User object, but I want to search, how can I do it. I understand if I remove to_a then it will work but then it will create another sql query.
Since it is an array of objects, you should use find with block:
users.find { |user| user.id == 1 }
User.find(1) is an ActiveRecord::FinderMethod. But when you already loaded all records into memory then those records are transformed into instances of User and stored in an Array. Therefore you need to use find or select which are implemented on Array like this:
users.find { |user| user.id == 1 } #=> returns the first found record
users.select { |user| user.id == 1 } #=> returns an array with all found record
Keep in mind that database queries are able to use efficient indexes when properly set up. Which makes database queries very fast. When you load all records into memory then those records need to be translated into proper instances. And searching on an array cannot use any index which means it could be (depending on the size of the array) slower than a new database query.
In my understanding the following ruby expressions should produce the same result.
Apparently I am missing something, this is a way too serious bug to go unnoticed...
# returns the number of ALL elements in the array
count = #quotation.quotation_items.count { |x| x.placement == current_placement}
# Does what I expect
count = (#quotation.quotation_items.find_all { |x| x.placement == current_placement }).length
quotation_items above is an ActiveRecord has_many association
#count does not take a block like that.
If you want to use conditions on a count, you would do:
#quotation.quotation_items.count(:conditions => "placement = #{current_placement}")
http://apidock.com/rails/ActiveRecord/Calculations/ClassMethods/count
If you're using ActiveRecord you need to keep in mind that there's a point where it's compiling conditions and clauses for a query and a point where you have a result set. Certain things only work in one mode or the other, though it tries to keep things pretty consistent regardless.
In your case you are expecting count to work like Enumerable, but that's still a database-level operator.
To fix that:
#quotation.quotation_items.where(placement: current_placement).count
That composes a query that counts only the things you need, something approximating:
SELECT COUNT(*) FROM quotation_items WHERE quotation_id=? AND placement=?
That's something that yields a single number and is considerably different than selecting every record, instantiating into models, then counting those using Enumerable.
Your usage of #count is incorrect.
I believe it doesn't accept a block. I'm not sure why it didn't return an error though.
you can use it like this :
count = #quotation.quotation_items.map{ |x| x.placement == current_placement}.count(true)
https://developers.google.com/appengine/docs/java/datastore/projectionqueries
Why a projected query such as this : SELECT A FROM kind WHERE A = 1 not supported ?
Because it makes no sense. You are asking
SELECT A FROM kind WHERE A = 1
so, give me A where A = 1. Well, you already know that A = 1. It makes no sense for DB to allow that.
The IN query is internally just a series of equals queries merged together, so the same logic applies to it.
The reasoning behind this could be that since you already have the values of the properties you are querying you don't need them returned by the query. This is probably a good thing in the long run, but honestly, it's something that App Engine should allow anyway. Even if it didn't actually fetch these values from the datastore, it should add them to the entities returned to you behind the scenes so you can go about your business.
Anyway, here's what you can do...
query = MyModel.query().filter(MyModel.prop1 == 'value1', MyModel.prop2 == 'value2)
results = query.fetch(projection=[MyModel.prop3])
for r in results:
r.prop1 = 'value1' # the value you KNOW is correct
r.prop2 = 'value2'
Again, would be nice for this to happen behind the scenes because I don't think it's something anybody should ever care about. If I mention a property in a projection list, I'm already stating that I want that property as part of my entities. I shouldn't have to do any more computation to get that to happen.
On the other hand, it's just an extra for-loop. :)
After much googling and console testing I need some help with arrays in rails. In a method I do a search in the db for all rows matching a certain requirement and put them in a variable. Next I want to call each on that array and loop through it. My problem is that sometimes only one row is matched in the initial search and .each causes a nomethoderror.
I called class on both situations, where there are multiple rows and only one row. When there are multiple rows the variable I dump them into is of the class array. If there is only one row, it is the class of the model.
How can I have an each loop that won't break when there's only one instance of an object in my search? I could hack something together with lots of conditional code, but I feel like I'm not seeing something really simple here.
Thanks!
Requested Code Below
#user = User.new(params[:user])
if #user.save
#scan the invites dbtable and if user email is present, add the new uid to the table
#talentInvites = TalentInvitation.find_by_email(#user.email)
unless #talentInvites.nil?
#talentInvites.each do |tiv|
tiv.update_attribute(:user_id, #user.id)
end
end
....more code...
Use find_all_by_email, it will always return an array, even empty.
#user = User.new(params[:user])
if #user.save
#scan the invites dbtable and if user email is present, add the new uid to the table
#talentInvites = TalentInvitation.find_all_by_email(#user.email)
unless #talentInvites.empty?
#talentInvites.each do |tiv|
tiv.update_attribute(:user_id, #user.id)
end
end