Detect and fail early when csv column names don't match usage

[garethbowen]

Expected Behaviour

When using select_*_from_file the csv file must have column names that exactly match the expected values. By default these are name and label, which can be overridden using additional parameters. When they don't match exactly web forms should give a clear and useful error so it's corrected early.

Observed Behaviour

The form loads but behaves strangely, for example, selecting one option selects them all because they all have a null value. This is particularly hard to debug when it's a trailing space in the column name.

Reproduction Steps

Use the form in this forum post: https://forum.getodk.org/t/error-message-on-using-csv-as-an-external-list/58214

Screenshots or Videos

Environment

• Browser version: all
• OS: all
• Web Forms version: latest

Additional Context

• Reported on the forum: https://forum.getodk.org/t/error-message-on-using-csv-as-an-external-list/58214
• Enketo handles the trailing whitespace gracefully.
• Collect throws an error when loading.

[lognaturel]

What do you think about throwing an error for any column name that contains a space? Column names are supposed to be valid XML identifiers. Here's a related XForms spec issue: getodk/xforms-spec#351

[garethbowen]

Yeah let's do that as well. Firstly checking that the CSV has valid column names (no spaces), and secondly checking that the names specified in the select question match the column names in the CSV. Potentially the first check could be done when uploading to Central, but there's no harm in checking in WF too.