Re: Node, Jade and Logic

Just my opinion of course, although you will find articles supporting the argument, you are better off doing this sort of thing on the client. Let's say you have a result set that you have obtained asynchronously on the server, but you want to manipulate/sort it further before it's useful, then let the client do it. If you get into the habit of doing it in your server side node.js code you are effectively blocking the event loop. You may not notice with a handful of clients attached, but ramp that up a notch or two and you soon have client requests waiting to be serviced for no good reason. Your server side code should be optimised to get that response back asap, so if you must do it server-side you need to hand it off to a child process to do it asynchronously.

Sent from my iPad

On 12 Apr 2016, at 01:15, Bradley Stone <bvstone@xxxxxxxxx> wrote:

I'm playing around a lot more with Node.js and Jade using Express on the
IBM i.

I'm just curious how others are handing condition logic, more importantly,
where.

As an example lets say you're listing customer order details. We can of
course limit records we get in a result set using the SQL. We can also
order things, etc..

Once you have the result set, are you doing any additional programming in
node or the jade template?

Here's an example...

I have a generic routine that returns a result set. I have another that
returns the field headings from the file...: (not checked for syntax.. )

var sql = "select RRN(a) as RRN, a.* from %s.%s a where CDEMAIL = '%s'";
sql = util.format(sql, Library, Table, email);

var customerDetailList = myStuff.getResultSet(sql);
var columns = myStuff.getFieldDescriptions();

I then pass these into my jade template as such:

res.render('viewCustomerDetail', {resultSet: customerDetailList,
columnList: columns});

My jade template then has some logic to replace certain headings if
required (like if they're too long). It also has logic so that certain
rows won't be shown... for example:

block content
- var dontShow = ['CDEMAIL', 'RRN', 'CDREGNET', 'CDMNTAX', 'CDDSTC']
- var replaceHeadings = {CDCREQ: 'Requested', CDDAYS: 'Days'}

each fieldValue, fieldKey in resultSet[0]
if (dontShow.indexOf(fieldKey) < 0)
th.small1(align="left")
if (!replaceHeadings[fieldKey])
=columnList[fieldKey]
else
=replaceHeadings[fieldKey]

This works really slick and is moving all the display logic to the
template. But, is this considered ok or is it better to do this type of
logic in the node.js? Manipulate the returned lists, replace headings,
remove columns if we don't want to display them, etc.

Doing things this way I find my templates are generic for lists. I just
need to update the dontShow and replaceHeadings objects for each specific
page. I understand I can limit the columns display using the SQL statement
but right now this is how I am doing things while playing around.

It also means I can update my display without needing to stop and restart
my server (very nice!). If I needed to remove or add a column and use the
SQL statement to select the columns I'd need to update the node route and
restart the server.

Just throwing out some ideas... thanks!

Brad
www.bvstools.com
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