CQL2-TEXT keywords are case sensitive

[sebastianfrey]

Description

Keywords like AND, OR, IN, etc. are are evaluated case-sensitive when used within a CQL2 text filter.

Steps to Reproduce

Create a filter with lower-case keywords such as the following one:

gemarkung_id = 870 and flurnummer = 0

Sample: https://ogcapi-test.lgl-bw.de/pygeoapi/collections/flurstueck/items?f=json&filter=gemarkung_id=870%20AND%20flurnummer=0

This will fail with:

{
    "code":"InvalidParameterValue",
    "type":"InvalidParameterValue",
    "description":"Bad CQL text"
}

Now create a filter with upper-case keywords such as the following one:

gemarkung_id = 870 AND flurnummer = 0

Sample: https://ogcapi-test.lgl-bw.de/pygeoapi/collections/flurstueck/items?f=json&filter=gemarkung_id=870%20AND%20flurnummer=0

This works as expected.

Expected behavior
As stated in the CQL specification https://portal.ogc.org/files/96288#cql-text Keywords in the BNF grammar are case-insensitive.

So I would expect, pygeoapi to evaluate keywords like AND, OR, IN, etc. case-insensitive.

Screenshots/Tracebacks

Environment

• OS: -
• Python version: -
• pygeoapi version: 0.19.0

Additional context
I already raised an issue in geopython/pygeofilter#121, because I thought at first that this module was causing the error. But as pointed out by @jrobinson-spk, it looks like the cause of the problem resides in pygeoapi.

If you need any further information or additional context, please let me know.