Where should all data formatting be? Can it be all in one place?

[instanttim]

Just an idea.

[jepefe]

From Python to PHP?

2014-03-21 2:49 GMT+01:00 Timothy Martin notifications@github.com:

Just an idea.

Reply to this email directly or view it on GitHubhttps://github.com//issues/18
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[instanttim]

Well, let me step back a second. I've added some data to the JSON that's generated by getstatus.php (#7), and I realized when inspecting the output that some numerical data was quoted, and other data wasn't. I looked into the JSON spec and as you'd expected, quoted values are expected to be interpreted as strings. This is what had led to some values being padded with extra zeros (#4).

So I realized/remembered that PHP's mysql API always gets everything out of the database as a string. The additional values I was creating for the JSON feed after the queries weren't properly shown without quotes. So I added a function that converts numbers to numbers and leaves strings as strings. Conveniently, I also added a check in there for the "99" temp value and change it to the "###" string.

The status area on the page only gets the summary from the database though. It gets current data from the "matelog" JSON file. So I went through the python and made sure that numerical values were cast or converted to ints and floats. Other string values I left as they were, or made sure they were specifically cast as string.

So now that both JSON feeds all perfect looking. But I'm looking at the whole system and thinking there's a cleaner way. In fact, right now there's even more formatting code over in the javascript, and I even removed some that now I wish was still there. Namely a bunch of "toFixed()" formatting to make sure that values have consistent numbers of decimal places. In a list of three kWh values you kind of want them to all line up or at least have the same number of decimals.

So I'm standing back and thinking about where all the formatting stuff should be. I certainly feel like I could do a bit more of the computation work over in the PHP. I have javascript that's calculating net values and wattages from the volts and amps that are coming from the database. Since the PHP walks through the results anyway, I should just do the computations server-side and make the javascript faster.

Another idea would be to have PHP do all the formatting as well, maybe even add the units and such. For example:
device.accumulated_ah_shunt_a.value = 15
device.accumulated_ah_shunt_a.formatted = "15.0 Ah"

And if that's the case, I even wondered why bother formatting the JSON from python at all? It could send the raw data as seen in the UDP packets essentially, although formatted in JSON. Is it more error prone to essentially be doing all this interpretation and formatting twice?

PS: I'm probably overthinking (and overbuilding) it.

[instanttim]

I've decided the JSON shouldn't be formatted. Those values need to be manipulated and used for graphing/charting etc.

I think the on-disk JSON should be representative of the data sent over from the data stream host. But perhaps the JSON should be pushed into a javascript object with methods to return formatted values.