Id: imperial units silently removed from ele tag

[SK53]

I was adding a peak from old OOC maps which have all elevation data in feet. I therefore entered 561 ft in the elevation field, so was somewhat surprised to find it rendered as 561 m. Testing shows that iD silenty strips any non-numeric text (including ",") from what is entered. Although ele:imperial is probably the most widely used tag for non-metric units, the ele tag with an indication of units (e.g., ft, feet, or "'") has always been in use. I would expect at least a warning, because there is a big difference between 561 feet & metres.

[bhousel]

Oh yeah, good catch @SK53
This is like #5438 / #5570

iD tries too hard to parse the numeric fields as numbers.

I think we probably need to take a first pass with a regex to decide whether the field is strictly numeric before trying to parse it.

[boothym]

Entering "561 ft" in the ele field is a tagging mistake. ele:imperial is used only once on the map - ele:ft is the more widely used tag (2k+).

It would be good if that could be picked up by iD - highlighting the field with a red border or similar if it's not strictly numeric. Basically input type="number" but without the browser's up/down controls, like the website field with type="url":

[systemed]

Entering "561 ft" in the ele field is a tagging mistake

Nope. Space-separated units have been used in OSM since time immemorial and most major clients parse them, such as osm2pgsql, mkgmap, OSRM, Graphhopper etc.

[bhousel]

Right, regardless of whether it happens to be a "tagging mistake" in the "ele" field - this is something iD needs to support in all the numeric fields.

I've actually been thinking of adding a "default units" property to each field that can have such a thing. There are a lot of them. But right now we include the default unit in the field label _sometimes_, and in the placeholder _sometimes_, but none of this is done consistently, and I'm sure it makes a mess for translators.

https://github.com/openstreetmap/iD/blob/master/data/presets/fields/fire_hydrant/pressure.json
https://github.com/openstreetmap/iD/blob/master/data/presets/fields/generator/output/electricity.json