Question

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

Answer 1

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