Double data entry

I’m developing database systems for clinical trials using Ruby on Rails.
Some trials require ‘double data entry’ as a form of validation; I need
to incorporate this into my system and am having difficulties. My plan
would be to have it work as follows:

  • Once a new record has been created, alongside the usual ‘edit’ option
    there would be a ‘second data entry’ option.
  • On clicking this, a ‘blank’ record would appear (as if a new record) -
    but when submitted, this form data would be compared with the existing
    record on the database.
  • If any differences were found this form would be displayed again with
    the relevant fields highlighted (Ã la validation, with the accompanying
    text showing the previous values) and the user asked to confirm.
  • After confirmation (or if the second input exactly matched the first
    initially) the reocrd would be saved and a flag will be set in the table
    that double data entry has been performed for that record.

Hopefully this could be handled in the same (edit) method by passing a
parameter (data_entry_mode or something). Ideally the second version
would not involve creating a new record in the database; any changes
would simply be written over the top of the first (perhaps the second
data entry values would be stored as session variables??).

Does anyone have any ideas on how best to accomplish this?

I apologise for the long and unusual nature of this query. Thank you for
any thoughts.

On Oct 16, 6:39 am, Tim C. [email protected]
wrote:

  • If any differences were found this form would be displayed again with
    data entry values would be stored as session variables??).

Does anyone have any ideas on how best to accomplish this?

I apologise for the long and unusual nature of this query. Thank you for
any thoughts.


Posted viahttp://www.ruby-forum.com/.

Hi Tim,

First off, I have an interest in this sort of application myself.
Please contact me off-list if you would like additional help.

The proper way to do double entry rather depends on your workflow.

  • Do you have the same person enter the data twice?
  • Does the second entry happen at a different time, or do you want to
    do it all in one form?

As a general rule, double entry makes for a bad user interface, but
there are times when it is necessary (password verifications show up a
lot).

In any event, one way to implement this would be through an ‘edit’ like
action.

  • record has been entered
  • user invokes the ‘verify’ action on the record.
  • ‘verify’ generates a blank form (much like a new item form) but
    passes the id of the record in a hidden field
  • on submission, load the original object in memory
  • cycle through all the attributes of the record looking for
    differences. Ignore at ‘created_at’ like attributes.
  • If all the relevant columns pass, then update the ‘verified_at’ with
    the timestamp of when it passed the test.
  • If not, then assign the ‘errors’ for the record and re-render the
    form with the discrepancies highlighted.

_Kevin
www.sciwerks.com

Hi Kevin

First off, I have an interest in this sort of application myself.
Please contact me off-list if you would like additional help.

Thank you. I expect I shall do so soon!

  • Do you have the same person enter the data twice?

No.

  • Does the second entry happen at a different time, or do you want to
    do it all in one form?

A different time. (The idea being that double data entry can be used as
an extra for some forms in some studies - and perhaps only for a sample
of the records, with a status flag to indicate if a given record has
been entered twice.)

In any event, one way to implement this would be through an ‘edit’ like
action.

  • record has been entered
  • user invokes the ‘verify’ action on the record.
  • ‘verify’ generates a blank form (much like a new item form) but
    passes the id of the record in a hidden field
  • on submission, load the original object in memory
  • cycle through all the attributes of the record looking for
    differences. Ignore at ‘created_at’ like attributes.
  • If all the relevant columns pass, then update the ‘verified_at’ with
    the timestamp of when it passed the test.
  • If not, then assign the ‘errors’ for the record and re-render the
    form with the discrepancies highlighted.

This is exactly the sort of process flow that I’m after! Now I just need
to work out the code. I shall have a go, but any help on these pages
would be appreciated (especially as, ideally, this might end up as a
plugin so that there wouldn’t be the need to write the same code in
every edit method!).

Just a thought, my acts_as_modified plugin may be of use to you when
looking
for differences between the records.

You could assign the new values to the original record then use
record.modified_attributes see any differences.

http://svn.viney.net.nz/things/rails/plugins/acts_as_modified

-Jonathan.

I’ve had a go at writing a verify method…

def verify
@subject = Subject.new
@subject.id = params[:id]

if request.post?
  @subject_original = Subject.find(params[:id])  #load original 

record
changes = [] #array to store changes
@confirm = true #when form is submitted, change button to
‘Confirm’
@subject_original.attributes.each do |key, value|
if params[:subject][key]
@transaction = record_transaction(‘subjects’, key,
@subject_original.id, value, params[:subject][key], value.class.to_s)
changes << @transaction if @transaction #write any changes
into array
end
end

  case params['commit']
    when "Next" then
      for change in changes
        @subject.errors.add(change.field, change.old_value.to_s)
      end
    when "Confirm" then
      @subject_original.update_attributes(params[:subject])
      @subject_original.save
  end
end

end

This uses a method called ‘record_transaction’ from my application
controller to only add to the changes array if there has been a change.
Jonathan - I’m sure that your plugin would be useful here for doing the
comparisons and building up the changes array instead of using
record_transaction - can you give me any help as to how I’d fit it into
the code above?

When the verification form is submitted, the page is currently
redisplayed with any differences shown as if they were validation
errors. (And the ‘next’ button changes to ‘confirm’ so that the next
form submission writes to the DB.) Rather than validation errors, is
there an easy way for me to write something such that I can do
@subject.verifications.add(…), which would work a bit like the
Automatic Rails validation, but, as well as highlighting fields with
differences, display the old values next to each differing field?

Thanks.

Thanks Jonathan.

This has saved me several lines of code and works a treat! What an
excellent plugin.

Tim

The docs should be enough:

http://svn.viney.net.nz/things/rails/plugins/acts_as_modified/lib/acts_as_modified.rb

But just quickly, you can do:

@subject = Subject.find(params[:id])
@subject.attributes = { :name => “New name” }

@subject.modified_attributes # { :name => “Old name” }
@subject.name_modified? # true
@subject.original_name # “Old Name”

@subject.modified? # true

Feel free to email me off-list if you want more assistance with the
plugin.

-Jonathan.

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