How to select in rails method using previous find array?

Question

I want to find array, but gow can i do this?

@model = Model.find(:first, :conditions => { :MOD_MFA_ID => params[:man]}) 
@ct = CountryDesignation.find(:first, :conditions => { :CDS_ID => "110000002"})

but :CDS_ID => "110000002" is not good. I need to select it via @model.Field, for example: :CDS_ID => @model.Field. But also @model is not just one entry, it's an array. So I need for every Model select CountryDesignation. But then I need to select from CountryDesignation array DesText array

@destext = DesText.find(:all, :conditions => { :TEX_ID => @ct.Field})

How to do this work? And how to correct view this?

%table
  %tr
    %th Mfa id
    %th Год начала выпуска
    %th Год завершения выпуска
  - @model.each do |model| 
    %tr
      %td= link_to model.MOD_ID, model
      %td= link_to model.MOD_PCON_START, model
      -if model.MOD_PCON_END.blank?
        %td= link_to "По настоящее время", model
      -else
        %td= link_to model.MOD_PCON_END, model
      -#%td= model.country_designations.des_texts.TEX_TEXT
      -#= link_to 'Show model', model
  %br
  - @destext.each do |t|
    name
    %td= t.TEX_ID
    %td= t.TEX_TEXT
  - @ct.each do |ct|
    ct
    %td= ct.CDS_ID
    %td= ct.CDS_TEX_ID

Brandan · Accepted Answer · 2012-04-22 16:37:23Z

2

You can use map. If the model attribute you're interested in were named cds_id:

@models = Model.all(:conditions => { :MOD_MFA_ID => params[:man] })
@ct = CountryDesignation.all(:conditions => { :CDS_ID => @models.map(&:cds_id) })

This essentially grabs the cds_id attribute of each model into an array and uses those values in a SQL IN clause. It returns an array of CountryDesignation objects that match.

answered Apr 22, 2012 at 16:37

Brandan

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8 Comments

byCoder Over a year ago

hm, no, I need field MOD_CDS_ID, so :CDS_ID => @models.MOD_CDS_ID like this

Brandan Over a year ago

Okay, then just replace cds_id with MOD_CDS_ID in my example. I don't know what what your models look like, so I'm just giving an example.

byCoder Over a year ago

like this all trouble is existing db(((

byCoder Over a year ago

COUNTRY_DESIGNATIONS has_many MODELS DES_TEXTS has_many COUNTRY_DESIGNATIONS MANUFACTURERS has_many MODELS

byCoder Over a year ago

how can i format this it in view, so that every model displays it ct and destext fields?

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Alex Westholm · Accepted Answer · 2012-04-22 16:34:48Z

0

What you're looking for is a way for ActiveRecord to handle the array in the same manner as an IN clause in SQL. Luckily, AR does that by default when passed an array. In other words, you should be able to write:

@model = Model.find(:first, :conditions => { :MOD_MFA_ID => })

answered Apr 22, 2012 at 16:34

Alex Westholm

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8 Comments

Alex Westholm Over a year ago

Oops, bad formatting. There was supposed to be an array before the closing }

Alex Westholm Over a year ago

Pavel, my solution is essentially the same as what you got from Brandan. In other words, to fit your problem, the answer will still be: CountryDesignation.all(:conditions => { :CDS_ID => @models.map(&:MOD_CSD_ID) })

byCoder Over a year ago

and what to do if ct always have uniq if, but one of it's field reffers to des_text, and this field can be equal for many ct.id

byCoder Over a year ago

how can i format this it in view, so that every model displays it ct and destext fields?

Alex Westholm Over a year ago

Are you asking how to get unique des_text rows based on the values in ct? Try: @destext = DesText.find(:all, :conditions => { :TEX_ID => @ct.map(&:Field).uniq}) ...This will result in an array of keys that are unique. Also, I would suggest reading up on ActiveRecord associations - it looks like there's a lot of overlap between what you're trying to do and associations.

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