How do I use CakePHP to append data to database when submitting from a form? - forms

Question

I've been developing this application for use in my biology lab where I require the following:
User adds in data into a text field.
When the user wants to update the text field, s/he cannot update the existing text, and can only append new text to the field.
Therefore, the form must contain a blank text field that the user can input text to append to the existing entry.
Ideally, I'd also like to append the timestamp for when each entry is recorded.
As you can see, it's sort of like a lab notebook, where the integrity of previously-entered data is important.
I'm having trouble with 2nd point, in that I don't know how to create a blank text field that saves the data to the corresponding field in the model.
Here is the code I currently have for the "view":
(I've tried to hide the existing data - "results_summary" - in a "hidden" element.)
<!-- File: /app/View/Experiments/update.ctp -->
<h1>Update Experiment</h1>
<h2>Objective:</h2>
<p><?php echo $experiment['Experiment']['objective']?></p>
<p>Notebook <?php echo $experiment['Experiment']['notebook_number'] ?>, Page <?php echo $experiment['Experiment']['notebook_page'] ?> </p>
<p>Date Started: <?php echo $experiment['Experiment']['date_started']?></p>
<p>Date Ended: <?php echo $experiment['Experiment']['date_ended']?></p>
<p>Project: <?php echo $experiment['Project']['title']?>
<p>Status: <?php echo $experiment['ExperimentStatus']['title']?>
<p>Results Summary:</p>
<p><?php echo $this->Form->create('Experiment', array('action' => 'update'));
echo $this->Form->hidden('results_summary');
echo $this->Form->text('results_summary');
echo $this->Form->end('Update');
//$experiment['Experiment']['results_summary']?></p>
Does anybody have clues as to how I could go about solving this problem? I'm quite lost right now, as I haven't had the experience coding this before.

Answer 1

Based on requirements 3 and 4, I would model the database in a way that each summary entry is stored in a separate row. You'll need a separate table for that, something like this:
id | experiment_id | summary_entry | summary_entry_timestamp
Column experiment_id is a foreign key to the related id on experiments table. Tables/models are related so that Experiment hasMany ExperimentSummaryEntry.
Then, logging to the experiment results summary will be a matter of inserting a new row on that table.

Answer 2

I would have to agree with #bfavaretto
Without seeing your database structure it is hard to be sure.
I suspect that you are doing
Project hasMany Experiment
Experiment hasOne ExperimentStatus
You need an additional
Experiment hasMany ExperimentEntry
the entries table need to have
id int(11), experiment_id int (11), content TEXT, created DATETIME
if you are okay using DATETIME field for timestamp then I suggest using **created because cakephp will auto fill in for you.
instead of update experiment, you do a add experimententry.
in the afterSave method of ExperimentEntry you do a
$this->Experiment->id = $this->data['ExperimentEntry']['experiment_id'];
$latestSummary = $this->Experiment->field('result_summary');
$latestSummary .= $this->data['ExperimentEntry']['content']; // you may need to add a newline before you append. up to you
$this->Experiment->save(array(
'Experiment' => array(
'result_summary' => $latestSummary
)));
Code is not tested so use at own risk.
** no corresponding page in cakephp 2.0 docs for created and modified but definitely this works. I have tried it before.