Ian, I think this project is a perfect place to start since you're only
dealing with one object and its data. I'll provide my thoughts and
hopefully it will help.
One thing I want to say is that you're still performing the steps
procedurally, but the data is manipulated as attributes of an object. You
are still going to create a form and then submit to a processing page that
validates everything. How you build the application remains unchanged.
> But I can not convert this to an object orientated design. I
> can create a simple object that would represent a trima
> machine which I believe is often called a bean
You're on the right track here. You create the Trima Bean. It simply holds
the attributes and get/set methods for each attribute of a trima machine.
Since the bean's function is to accept and give the data while it's being
manipulated, the validation should be done at this point.
> I think I understand how one would separate the database
> logic into a DAO.
Correct, the TrimaDAO handles *all* access to the datasource. This is its
only purpose, which is why the data should not be validated here. It has
the CRUD methods [create/read/update/delete]. Each of these methods has one
argument which accepts a Trima Bean which is a struct.
<cfargument name="TrimaBean" type="struct" required="true">
So a sample call would be:
trimaDAO = createobject("component", "com.bloodsource.trimaDAO");
trimaDAO.update(trimaBean);
> Is it good or bad to put bad
> and/or partial data into the bean because some of the form
> data was good and some was bad?
IMHO, since validation is done by the bean, partial data in one of the
attributes is not acceptable.
> How does one use a form first to show the current bean data and
> then to show the form submitted data with error feedback?
FORM PAGE
--------------
<cfscript>
trimaBean = createobject("component", "com.bloodsource.trimaBean");
trimaDAO = createobject("component", "com.bloodsource.trimaDAO");
trimaBean.setMachineID("64");
currentTrimaBean = trimaDAO.read(trimaBean);
</cfscript>
<form action="ProcessTrimaBean.cfm">
<input type="text" name="PlateletLevel"
value="#currentTrimaBean.getPlateletLevel()#">
<input type="text" name="BloodType"
value="#currentTrimaBean.getBloodType()#">
etc...
</form>
PROCESSING PAGE
------------------
<cftry>
<cfscript>
trimaBean = createobject("component", "com.bloodsource.trimaBean");
trimaDAO = createobject("component", "com.bloodsource.trimaDAO");
trimaBean.setPlateletLevel(form.PlateletLevel);
trimaBean.setBloodType(form.BloodType);
etc...
trimaDAO.update(trimaBean);
</cfscript>
<cfcatch>
<cfset alertMessage = trimaBean.invalidDataMessage>
-- DISPLAY ERROR INFORMATION HERE --
</cfcatch>
<cftry>
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