Find a record by bigint column with wildcard - ruby-on-rails

I have an API that has a database with UPC-12 values in it. Sometimes API calls will come in with UPC-10 codes. My db upc column is bigint, so it removes the leading 0 on a UPC-12 value. That leaves the last digit as a wildcard when comparing to UPC-10.
I'd like to be able to check a UPC-10 value against records in the db to see if there's a match. Since I can't use LIKE, how do I do that?
The goal is to do something like:
def self.pull_product(upc)
upc_string = upc.to_s
if upc_string.length == 10
# product = Product.where... use a wildcard to try and match to existing record
else
product = Product.find_by_upc(upc)
end
end
This Rails 4 and Postgresql.
Just to clarify:
I might have a UPC-10 api call with a upc param like: 7618600002. My database has the UPC-12 equivalent: 76186000023. So if I just query for the param in the api call, I'll get nil.
I need a way to match the the UPC-10 param against my UPC-12 value in the database.

You need to use SQL like this:
upc between upc_string::int*10 and upc_string::int*10+9
I have no idea how to code it in Rails though.

Related

How to create serial number for ruby on rails?

I want to create ticket number by serial number, eg. T-0001, T-0002, T-0003,
for ruby on rails project. How to make this?
Admission.transaction do
cus = #admission.customer
cus.inpatient_id = cus.inpatient_id || "I-%.6d" % cus.id
cus.save
end
Most rails servers are multi-threaded. Meaning many requests will be processed in parallel. You can imagine two processes trying to create a new serial number at the same point in time - duplicate ticket numbers! - not what we expect for sure.
It is better we delegate this task of creating ids to the database itself. So instead of the default auto-increment ids (1,2,3,4...), we will tell database to create ids in this format (T-0001, T-0002, ...). This can be achieved using custom sequences. I am assuming postgres database here, but should be same for mysql.
First create sequence
CREATE SEQUENCE ticket_seq;
But sequences don't allow strings so we convert them to strings and format them:
SELECT 'T-'||to_char(nextval('ticket_seq'), 'FM0000');
This will return values like T-0001, T-0002 ...
Note: We have just created a sequence, you need to tell database to use this sequence instead.
Check: https://stackoverflow.com/a/10736871/3507206
here is just sample to generate your required formatted series on range:
> (0..5).map{|e| "T-#{e.to_s.rjust(4, "0")}"}
#=> ["T-0000", "T-0001", "T-0002", "T-0003", "T-0004", "T-0005"]
If you are using PG / MySQL you can use object's id for unique number (ID- primary key is always serialize and unique)
UPDATE: as per OP's comment:
Admission.transaction do
cus = #admission.customer
cus.inpatient_id = cus.inpatient_id || "T-#{cus.id.to_s.rjust(4, "0")}"
cus.save
end

Combining distinct with another condition

I'm migrating a Rails 3.2 app to Rails 5.1 (not before time) and I've hit a problem with a where query.
The code that works on Rails 3.2 looks like this,
sales = SalesActivity.select('DISTINCT batch_id').where('salesperson_id = ?', sales_id)
sales.find_each(batch_size: 2000) do |batchToProcess|
.....
When I run this code under Rails 5.1, it appears to cause the following error when it attempts the for_each,
ArgumentError (Primary key not included in the custom select clause):
I want to end up with an array(?) of unique batch_ids for the given salesperson_id that I can then traverse, as was working with Rails 3.2.
For reasons I don't understand, it looks like I might need to include the whole record to traverse through (my thinking being that I need to include the Primary key)?
I'm trying to rephrase the 'where', and have tried the following,
sales = SalesActivity.where(salesperson_id: sales_id).select(:batch_id).distinct
However, the combined ActiveRecordQuery applies the DISTINCT to both the salesperson_id AND the batch_id - that's #FAIL1
Also, because I'm still using a select (to let distinct know which column I want to be 'distinct') it also still only selects the batch_id column of course, which I am trying to avoid - that's #FAIL2
How can I efficiently pull all unique batch_id records for a given salesperson_id, so I can then for_each them?
Thanks!
How about:
SalesActivity.where(salesperson_id: sales_id).pluck('DISTINCT batch_id')
May need to change up the ordering of where and pluck, but pluck should return an array of the batch_ids

How to get weighted average grouped by a column

I have a model Company that have columns pbr, market_cap and category.
To get averages of pbr grouped by category, I can use group method.
Company.group(:category).average(:pbr)
But there is no method for weighted average.
To get weighted averages I need to run this SQL code.
select case when sum(market_cap) = 0 then 0 else sum(pbr * market_cap) / sum(market_cap) end as weighted_average_pbr, category AS category FROM "companies" GROUP BY "companies"."category";
In psql this query works fine. But I don't know how to use from Rails.
sql = %q(select case when sum(market_cap) = 0 then 0 else sum(pbr * market_cap) / sum(market_cap) end as weighted_average_pbr, category AS category FROM "companies" GROUP BY "companies"."category";)
ActiveRecord::Base.connection.select_all(sql)
returns a error:
output error: #<NoMethodError: undefined method `keys' for #<Array:0x007ff441efa618>>
It would be best if I can extend Rails method so that I can use
Company.group(:category).weighted_average(:pbr)
But I heard that extending rails query is a bit tweaky, now I just want to know how to run the result of sql from Rails.
Does anyone knows how to do it?
Version
rails: 4.2.1
What version of Rails are you using? I don't get that error with Rails 4.2. In Rails 3.2 select_all used to return an Array, and in 4.2 it returns an ActiveRecord::Result. But in either case, it is correct that there is no keys method. Instead you need to call keys on each element of the Array or Result. It sounds like the problem isn't from running the query, but from what you're doing afterward.
In any case, to get the more fluent approach you've described, you could do this:
class Company
scope :weighted_average, lambda{|col|
select("companies.category").
select(<<-EOQ)
(CASE WHEN SUM(market_cap) = 0 THEN 0
ELSE SUM(#{col} * market_cap) / SUM(market_cap)
END) AS weighted_average_#{col}
EOQ
}
This will let you say Company.group(:category).weighted_average(:pbr), and you will get a collection of Company instances. Each one will have an extra weighted_average_pbr attribute, so you can do this:
Company.group(:category).weighted_average(:pbr).each do |c|
puts c.weighted_average_pbr
end
These instances will not have their normal attributes, but they will have category. That is because they do not represent individual Companies, but groups of companies with the same category. If you want to group by something else, you could parameterize the lambda to take the grouping column. In that case you might as well move the group call into the lambda too.
Now be warned that the parameter to weighted_average goes straight into your SQL query without escaping, since it is a column name. So make sure you don't pass user input to that method, or you'll have a SQL injection vulnerability. In fact I would probably put a guard inside the lambda, something like raise "NOPE" unless col =~ %r{\A[a-zA-Z0-9_]+\Z}.
The more general lesson is that you can use select to include extra SQL expressions, and have Rails magically treat those as attributes on the instances returned from the query.
Also note that unlike with select_all where you get a bunch of hashes, with this approach you get a bunch of Company instances. So again there is no keys method! :-)

Query in a string column for one of the value in an array like multiple OR (using full text search)

In a rails 4 app, in one model I have a column containing multiple ids as a string with comma separated values.
"123,4568,12"
I have a "search" engine that I use to retrieve the records with one or many values using the full text search of postgresql I can do something like this which is very useful:
records = MyModel.where("my_models.col_name ## ?", ["12","234"])
This return all the records that have both 12 and 234 in the targeted column. The array comes from a form with a multiple select.
Now I'm trying to make a query that will find all the records that have either 12 or 234 in there string.
I was hopping to be able to do something like:
records = MyModel.where("my_models.col_name IN (?)", ["12","234"])
But it's not working.
Should I iterate through all the values in the array to build a query with multiple OR ? Is there something more appropriate to do this?
EDIT / TL;DR
#BoraMa answer is a good way to achieve this.
To find all the records containing one or more ids referenced in the request use:
records = MyModel.where("my_models.col_name ## to_tsquery(?)", ["12","234"].join('|'))
You need the to_tsquery(?) and the join with a single pipe |to do a OR like query.
To find all the records containing exactly all the ids in the query use:
records = MyModel.where("my_models.col_name ## ?", ["12","234"])
And of course replace ["12","234"] with something like params[:params_from_my_form]
Postgres documentation for full text search
If you already started to use the fulltext search in Postgres in the first place,I'd try to leverage it again. I think you can use a fulltext OR query which can be constructed like this:
records = MyModel.where("my_models.col_name ## to_tsquery(?)", ["12","234"].join(" | "));
This uses the | operator for ORing fulltext queries in Postgres. I have not tested this and maybe you'll need to do to_tsvector('my_models.col_name') for this to work.
See the documentation for more info.
Suppose your ids are :
a="1,2,3,4"
You can simply use:
ModelName.find(a)
This will give you all the record of that model whose id is present in a.
I just think a super simple solution, we just sort the ids in saving callback of MyModel, then the query must be easier:
class MyModel < ActiveRecord::Base
before_save :sort_ids_in_col_name, if: :col_name_changed?
private
def sort_ids_in_col_name
self.col_name = self.col_name.to_s.split(',').sort.join(',')
end
end
Then the query will be easy:
ids = ["12","234"]
records = MyModel.where(col_name: ids.sort.join(',')

Passing params to sql query

So, in my rails app I developed a search filter where I am using sliders. For example, I want to show orders where the price is between min value and max value which comes from the slider in params. I have column in my db called "price" and params[:priceMin], params[:priceMax]. So I can't write something kinda MyModel.where(params).... You may say, that I should do something like MyModel.where('price >= ? AND price <= ?', params[:priceMin], params[:priceMax]) but there is a problem: the number of search criteria depends on user desire, so I don't know the size of params hash that passes to query. Are there any ways to solve this problem?
UPDATE
I've already done it this way
def query_senders
query = ""
if params.has_key?(:place_from)
query += query_and(query) + "place_from='#{params[:place_from]}'"
end
if params.has_key?(:expected_price_min) and params.has_key?(:expected_price_max)
query += query_and(query) + "price >= '#{params[:expected_price_min]}' AND price <= '#{params[:expected_price_max]}'"
end...
but according to ruby guides (http://guides.rubyonrails.org/active_record_querying.html) this approach is bad because of SQL injection danger.
You can get the size of params hash by doing params.count. By the way you described it, it still seems that you will know what parameters can be passed by the user. So just check whether they're present, and split the query accordingly.
Edited:
def query_string
return = {}
if params[:whatever].present?
return.merge({whatever: #{params[:whatever]}}"
elsif ...
end
The above would form a hash for all of the exact values you're searching for, avoiding SQL injection. Then for such filters as prices you can just check whether the values are in correct format (numbers only) and only perform if so.

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