No matter what language I'm using I always need to display a list of strings separated by some delimiter.
Let's say, I have a collection of products and need to display its names separated by ', '.
So I have a collection of Products, where each one has a 'name' attribute. I'm looking for some Rails method/helper (if it doesn't exist, maybe you can give me ideas to build it in a rails way) that will receive a collection, an attribute/method that will be called on each collection item and a string for the separator.
But I want something that does not include the separator at the end, because I will end with "Notebook, Computer, Keyboard, Mouse, " that 2 last characters should not be there.
Ex:
concat_ws(#products, :title, ", ")
#displays: Notebook, Computer, Keyboard, Mouse
Supposing #products has 4 products with that names of course.
Thanks!
you should try the helper to_sentence.
If you have an array, you can do something like
array.to_sentence. If your array has the data banana, apple, chocolate it will become:
banana, apple and chocolate.
So now if you have your AR Model with a field named, you could do something like
MyModel.all.map { |r| r.name }.to_sentence
#products.map(&:title).join(', ')
As #VP mentioned, Array#to_sentence does this job well in rails. The code for it is here:
https://github.com/rails/rails/blob/master/activesupport/lib/active_support/core_ext/array/conversions.rb
Saying that, its use of the Oxford Comma is questionable :-)
Related
Within my house table I have a postcode for each house.
I also have an index view for my housing table that contains a table which contains headings such as 'Name', 'Address', 'State'. I was looking to integrate a text_field_tag that would allow user's to input the 9 digits of a postcode in order to filter the table to only show the house with that postcode. However, I also want the user to be able to input the first 4 digits of their postcode e.g. '7644' and it would display all houses that begin with '7644' e.g. two records one with the postcode of the '76444-5645' and '76443-123'. Ideally I would apply logic through my '#search' variable within my houses controller. However I am up to any ideas or tips.
In order to instantiate the house model I would use #house = House.all
I'll be honest I don't know where to begin with this. I have arel_sql in my system so I assume that would be used to query for the search.
It depends on how your models/controllers are defined but you're probably looking for the SQL operator LIKE + '%', which allows you to search for a pattern in a given column. Example:
LIKE Operator
Description
WHERE CustomerName LIKE 'a%'
Finds any values that start with "a"
Assuming you're using ActiveRecord and your model is House, it wouldn't event need to instantiate all houses. Your code would look something like this:
postcode = '7644'
#houses = House.where('postcode LIKE ?', "#{postcode}%") # this returns where the postcode starts with '7644'
another similar SO answer for reference
I'm using Rails 5.0.1 and Postgresql as my database. I have a table with column :content which contains words.
The problem: When I'm looking for a specific word, I want to see if the word contains letters (chars) of my choice. Let's say i want to DB to return words containg letters "a", "b" and "c" (all of them, but with no specific order)
What I'm doing: I found that i could use
Word.where("content like ?", "%a%").where("content like ?", "%b%").where("content like ?", "%c%")
OR
Word.where("content like ? content like ? content like ?", "%a%", "%b%", "%c%")
In both cases even if i switch order of given letters/substrings it works fine, ex. both would find word "back", "cab" etc..
The question: Is there any better/more DRY way to do it? What if want to find word with 8 different letters? Do i have to use "content like ?" 8 times? Is it possible to pass arguments as an array? (let's assume i don't know how many letters user will input)
PostgreSQL has a handy expr op all (array) expression so you can say things like:
where content like all (array['%a%', '%b%', '%c'])
as a short form of:
where content like '%a%'
and content like '%b%'
and content like '%c%'
Also, ActiveRecord will conveniently replace a ? placeholder with a comma-delimited list if you hand it a Ruby array. That lets you say things like:
Word.where('content like all (array[?])', %w[a b c].map { |c| "%#{c}%" })
and:
Word.where('content like all (array[?])', some_other_array.map { |c| "%#{c}%" })
I found a solution:
letters = ["%a%", "%b%", "%c%"]
Word.where((['content LIKE ?'] * letters.size).join(' AND '), *letters)
This is easy and much better than I was using.
I think the SIMILAR TO operator might help. It allows you to pass in a regular expression that you could construct on the fly.
letters = ['a', 'b', 'c']
pattern = "%(#{letters.join('|')})%"
Word.where("content SIMILAR TO ?", pattern)
So let's say i have a Customer model with array column phones.
It's pretty easy to find all customers with given phone
Customer.where('? = ANY(phones)', '+79851234567')
But i can't figure out how to use LIKE with wildcard when i want to find customers with phones similar to given one, something like:
Customer.where('ANY(phones) LIKE ?', '+7985%')
I'm using PostgreSQL 9.5 and Rais 4.2
Any ideas?
I think, first of all, its better to use second table phones with fields customer_id, phone_number. I think it's more rails way ). In this way you can use this query
Phone.where("phone_number LIKE ?", '%PART%').first.customer
If you serialize your array in some text field, by example JSON, you should use % on both sides of your pattern:
Customer.where('phones LIKE ?', '%+7985%')
If you have an array in your database, you should use unnest() function to expand an array to a set of rows.
Can you try this
Customer.where("array_to_string(phones, ', ') like ?", '+7985%')
I believe this will work.
I have a web page where a user can search through documents in a mongoDB collection.
I get the user's input through #q = params[:search].to_s
I then run a mongoid query:
#story = Story.any_of( { :Tags => /#{#q}/i}, {:Name => /#{#q}/i}, {:Genre => {/#{#q}/i}} )
This works fine if the user looks for something like 'humor' 'romantic comedy' or 'mystery'. But if looking for 'romance fiction', nothing comes up. Basically I'd like to add 'and' 'or' functionality to my search so that it will find documents in the database that are related to all strings that a user types into the input field.
How can this be done while still maintaining the substring search capabilties I currently have?Thanks in advance for help!
UPDATE:
Per Eugene's comment below...
I tried converting to case insensitive with #q.map! { |x| x="/#{x}/i"}. It does save it properly as ["/romantic/i","/comedy/i"]. But the query Story.any_of({:Tags.in => #q}, {:Story.in => #q})finds nothing.
When I change the array to be ["Romantic","Comedy"]. Then it does.
How can I properly make it case insensitive?
Final:
Removing the quotes worked.
However there is now no way to use an .and() search to find a book that has both words in all these fields.
to create an OR statement, you can convert the string into an array of strings, and then convert the array of strings into an array of regex and then use the '$in' option. So first, pick a delimeter - perhaps commas or space or you can set up a custom like ||. Let's say you do comma seperated. When user enters:
romantic, comedy
you split that into ['romantic', 'comedy'], then convert that to [/romantic/i, /comedy/i] then do
#story = Story.any_of( { :Tags.in => [/romantic/i, /comedy/i]}....
To create an AND query, it can get a little more complicated. There is an elemMatch function you could use.
I don't think you could do {:Tags => /romantic/i, :Tags => /comedy/i }
So my best thought would be to do sequential queries, even though there would be a performance hit, but if your DB isn't that big, it shouldn't be a big issue. So if you want Romantic AND Comedy you can do
query 1: find all collections that match /romantic/i
query 2: take results of query 1, find all collections that match /comedy/i
And so on by iterating through your array of selectors.
I'm experimenting with a few concepts (actually playing and learning by building a RoR version of the 1978 database WHATSIT?).
It basically is a has_many :through structure with Subject -> Tags <- Value. I've tried to replicate a little of the command line structure by using a query text field to enter the commands. Basically things like: What's steve's phone.
Anyhow, with that interface most of the searches use ILIKE. I though about enhancing it by allowing OR conditions using some form of an array. Something like What's steve's [son,daugher]. I got it working by creating the ILIKE clause directly, but not with string replacement.
def bracket_to_ilike(arrel,name,bracket)
bracket_array = bracket.match(/\[([^\]]+)\]/)[1].split(',')
like_clause = bracket_array.map {|i| "#{name} ILiKE '#{i}' "}.join(" OR ")
arrel.where(like_clause)
end
bracket_to_ilike(tags,'tags.name','[son,daughter]') produces the like clause tags.name ILiKE 'son' OR tags.name ILiKE 'daughter'
And it get the relations, but with all the talk about using the form ("tags.name ILiKE ? OR tags.name ? ",v1,v2,vN..)., I though I'd ask if anyone has any ideas on how to do that.
Creating variables on the fly is doable from what I've searched, but not in favor. I just wondered if anyone has tried creating a method that can add a where clause that has a variable number parameters.I tried sending the where clause to the relation, but it didn't like that.
Steve
Couple of things to watch out for in your code...
What will happen when one of the elements of bracket_array contains a single quote?
What will happen if I take it step farther and set an element to say "'; drop tables..."?
My first stab at refactoring your code would be to see if Arel can do it. Or Sequeel, or whatever they call the "metawhere" gem these days. My second stab would be something like this:
arrel.where( [ bracket_array.size.times.map{"#{name} ILIKE ?"}.join(' OR '), *bracket_array ])
I didn't test it, but the idea is to use the size of bracket_array to generate a string of OR'd conditions, then use the splat operator to pass in all the values.
Thanks to Phillip for pointing me in the right direction.
I didn't know you could pass an array to a where clause - that opened up some options
I had used the splat operator a few times, but it didn't hit me that it actually creates an object(variable)
The [son,daughter] stuff was just a console exercise to see what I could do, but not sure what I was going to do with it. I ended up taking the model association and creating the array out of the picture and implemented OR searches.
def array_to_ilike(col_name,keys)
ilike = [keys.map {|i| "#{col_name} ILiKE ? "}.join(" OR "), *keys ]
#ilike = [keys.size.times.map{"#{col_name} ILIKE ?"}.join(' OR '), *keys ]
#both work, guess its just what you are use to.
end
I then allowed a pipe(|) character in my subject,tag,values searches, so a WHATSIT style question
What's Steve's Phone Home|Work => displays home and work phone
steve phone home|work The 's stuff is just for show
steve son|daughter => displays children
phone james%|lori% => displays phone number for anyone who's name starts with james or lori
james%|lori% => dumps all information on anyone who's name starts with james or lori
The query then parses the command and if it encounters a | in any of the words, it will do things like:
t_ilike = array_to_ilike('tags.name',name.split("|"))
# or I actually stored it off on the inital parse
t_ilike = #tuple[:tag][:ilike] ||= ['tags.name ilike ?',tag]
Again this is just a learning exercise in creating a non-CRUD class to deal with the parsing and searching.
Steve