Extract data from array in DB (rails)

Question

I am trying to extract some data from an array with the following syntax:

@entries_from_db = XrEntry.find(:all, :conditions => [:FeedURI => uri ], :select => 'json')

The :FeedURI is the record that contains an array with uri's ["123456", "23345", "4453"] The uri is the variable wich contains the current uri.

The statement I'm trying to make is 'select JSON from XrEntry where FeedURI contains uri' Im stuck on the part to access the array and always get several error msg's when I'm trying different code.

Does anyone has an idea? Thanks!

Wouter A · Accepted Answer · 2011-01-21 09:16:18Z

1

I solved it with this syntax

@entries_from_db = XrEntry.find(:all, :conditions => ["FeedURI like ?", "%#{uri}%"] , :select => 'json')

the "%#{your_rails_variable}%" is needed to read in an array

answered Jan 21, 2011 at 9:16

Wouter A

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DanneManne · Accepted Answer · 2011-01-21 08:36:18Z

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You seem to have switched the condition syntax. you chould start with the db attribute and then the variable.

@entries_from_db = XrEntry.find(:all, 
                                :conditions => { :uri => FeedURI }, 
                                :select => 'json')

That will return an array of XrEntry objects with only the json attribute present. To get an array of only the json data you could map it like this:

@json_array = @entries_from_db.map(&:json)

answered Jan 21, 2011 at 8:36

DanneManne

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5 Comments

Wouter A Over a year ago

Maybe I explained it wrong: 'FeedURI' is the record in the db wich contains an array of uri's 'uri' is the variable with the current uri so I'm trying to read from an array in a record (FeedURI) wich contains the current (uri)

DanneManne Over a year ago

Hmm, that seems a little strange. If the database field is called FeedURI, it is not following rails naming convention... Anyway, I guess you could use sql syntax instead, :conditions => ["FeedURI contains ?", uri] Would that work?

Wouter A Over a year ago

Thanks for the DB naming info (I'll be changing that tonight). 'contains' throws an error, I've tried it with 'like' and '=', they both work but it returns nothing...very strange. I'll have to dive into the SQL syntax some more.

DanneManne Over a year ago

I'm not an expert in sql unfortunately so I just wrote what you wrote in the question :) My guess though is that this kind of syntax might not be common for all databases. But for MySQL, try ["FeedURI.contains(?)", uri]

Wouter A Over a year ago

I solved it with this syntax ["FeedURI like ?", "%#{uri}%"] Thanks for the help

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