Search and replace in SQL

Have a situation where had to change a bunch of values on a one-off in a db. Could have written a script to do it, but found this really useful tip

UPDATE table_name SET field_name = REPLACE(field_name, 'old_string','new_string')

works to change:
/OLD/PATH/TO/SOMEDATA/A_FILES

to:
/NEW/PATH/TO/A_LOT/MORE/NEW_DATA/A_FILES

Getting the id of the object when inside form_for or fields_for

This was a post I put on StackOverflow - and then found the answer about 20 mins later ... doh

I have the following code that is generating fields for an invoice

THis is in the edit.html.erb for the invoice class

<% f.fields_for(:invoice_items) do |f| %>
<%= render :partial => 'invoice_items/fields', :locals => {:f => f} %>
<% end %>

and I generate the invoice_items as part of the invoice object

@invoice = Invoice.find(params[:id], :include => :invoice_items, :order =>"invoice_items.display_order")

It works just fine, but I need to wrap each one in a div, and assign that object's id to the div. (div id=i_2345 - that kind of thing) so I can use jQuery wizardry.

Where I am stumbling like a new-born foal is how do I access the the id of the invoice_item that is being called?

And the answer is ...

f.object.id

jQuery readonly on checkboxes

Well here is an annoying thing.
You can't set the readonly attribute to checkboxes or select. And if you set disabled="disabled" the values aren't passed in the submit.
Bum.

Fields_for, symbols and instance variables

Had a problem with fields_for and accepts_nested_attributes_for

The invoice class has many invoice items, but they have to be displayed in a certain order. Originally I had an @invoice_items variable - but the form wasn't looking at this.
However, a genius on teh Ruby forum posted the following:
@invoice = Invoice.find(params[:id], :include => :invoice_items, :order "invoice_items.display_order")

When the invoice calls the invoice_items they are already in the object and in the right place. Now he has pointed it out to me, I get what it is - but don't think I would have come up with that on my own.

Transactions

Used them for the first time - and love them.
I have a situation where a job can have many editions. An edition has many pages. If you create a new page for a job, you must create it for every edition. Likewise if you delete a page from a job, you must delete it from every edition. You must never end up in a situation where one page is deleted from one edition, but for some reason it fails on the next one.
Enter transactions.

This is my destroy action (handled by jQuery rather than the inbuilt rails method)
def destroy
@page = Page.find(params[:id])
@pages = Page.find_all_by_job_id_and_page_name_or_no(@job.id, @page.page_name_or_no)
invalid = false
Page.transaction do
@pages.each do |page|
begin
page.destroy
rescue ActiveRecord::StatementInvalid
invalid = true
end
end
end
if invalid
respond_to do |format|
format.html { render :action => "new" }
format.js {render :text => "-1" }
format.xml { render :xml => @page.errors, :status => :unprocessable_entity }
end
else
respond_to do |format|
format.html { redirect_to(pages_url) }
format.js {render :json => @page.id.to_json }
format.xml { head :ok }
end
end
end


And it all works.

Didn't know this one

pages = Page.find_all_by_job_id(18511).collect(&:page_name_or_no)

gives me an array with just that field. Sweet.

more on iText

Have to be able to merge pages - so playing more with iText and the following worked (eventually)

>> require 'rjb'
=> ["RjbConf"]
>> Rjb::load('/var/www/html/renaissance/lib/iText.jar')
=> nil
>> FileOutputStream = Rjb::import('java.io.FileOutputStream')
=> #
>> Color = Rjb::import('java.awt.Color')
=> #
>> Element = Rjb::import('com.itextpdf.text.Element')
=> #
>> Document = Rjb::import('com.itextpdf.text.Document')
=> #
>> Font = Rjb::import('com.itextpdf.text.Font')
=> #
>> FontFactory = Rjb::import('com.itextpdf.text.FontFactory')
=> #
>> PageSize = Rjb::import('com.itextpdf.text.PageSize')
=> #
>> Paragraph = Rjb::import('com.itextpdf.text.Paragraph')
=> #
>> Phrase = Rjb::import('com.itextpdf.text.Phrase')
=> #
>> BaseFont = Rjb::import('com.itextpdf.text.pdf.BaseFont')
=> #
>> ColumnText = Rjb::import('com.itextpdf.text.pdf.ColumnText')
=> #
>> PdfPageEvent = Rjb::import('com.itextpdf.text.pdf.PdfPageEvent')
=> #
>> PdfPCell = Rjb::import('com.itextpdf.text.pdf.PdfPCell')
=> #
>> PdfContentByte = Rjb::import('com.itextpdf.text.pdf.PdfContentByte')
=> #
>> PdfPTable = Rjb::import('com.itextpdf.text.pdf.PdfPTable')
=> #
>> PdfWriter = Rjb::import('com.itextpdf.text.pdf.PdfWriter')
(irb):18: warning: already initialized constant NAME
=> #
>> PdfReader = Rjb::import('com.itextpdf.text.pdf.PdfReader')
=> #
>> pdfTest = PdfReader.new('/tmp/test.pdf')
=> #<#:0x2b0282c08e38>
>> pdfTest2 = PdfReader.new('/tmp/test2.pdf')
=> #<#:0x2b0282c03ff0>
>> document = Document.new
=> #<#:0x2b0282c00f80>

>> pdf_writer = PdfWriter.getInstance(document, FileOutputStream.new("/tmp/merge.pdf"))
=> #<#:0x2b0282bf55b8>
>> document.open
=> nil
>> cb = pdf_writer.getDirectContent()
=> #<#:0x2b0282bef898>
>> document.newPage
=> true
>> page1 = pdf_writer.getImportedPage(pdfTest, 1)
=> #<#:0x2b0282be2b20>
>> cb.addTemplate(page1, 0, 0)
=> nil
>> document.newPage
=> true
>> page2 = pdf_writer.getImportedPage(pdfTest2, 1)
=> #<#:0x2b0282bd7a18>
>> cb.addTemplate(page2, 0, 0)
=> nil
>> document.close
=> nil
>>

NOw have a two page pdf - hurrah (again)