WCPS_Supports user defined band names in range constructor

[Bang Pham Huu]

current WCPS checks band names strictly (i.e: if in range constructor has a non-existing band, it will throw exception). This is necesary as in netCDF, it can write in coverage metadata user defined band names and should be supported.

WCPS query example:

for c in ( test_rgb ) return encode(
 { blueTEST: c.red; redTEST: c.blue }.redTEST
, "netcdf")

the output should have redTEST as band name in netCDF.

\"redTEST\":{
   \"type\":\"unsigned char\",\"metadata\":{\"units\":\"10^0\"},\"name\":\"redTEST\"}

Furthermore, a range constructor with a single field should only translate the field expression to rasql, and not to a whole range constructor. E.g.

single field

WCPS:
for c in (test_rgb) return {blue: c.red}
rasql:
select c.red from test_rgb as c

multi field

WCPS:
for c in (test_rgb) return {blue: c.red; red: c.blue}
rasql:
select {c.red, c.blue} from test_rgb as c

[Bang Pham Huu]

Note: comment moved to ticket #1437

There is a problem with choosing the metadata of the range, e.g:

 {redTEST: ( (c.red + c.blue + c.green) / 3 ) * (c.green);}

it will need to get some metadata for redTEST (e.g: data type, metadata, units,…) not only the name. To do this, it need to consider from the above expression, which band name will be chosen to assign to redTEST (c.red or c.blue or c.green) ?

as c.red can have different metadata (e.g: c.red: unit: 10, data type: float, nilValues: 100)

c.blue: unit: 10, data type: float, nilValues: 200)
c.green: unit: 10, data type: float, nilValues: 300)

current I think WCPS will take it from c.red as it is from leftmost one and it will be propagated from left to right (but still need to confirm!).

then it will write in netCDF as

\"redTEST\":{
   \"type\":\"unsigned char\",\"metadata\":{\"units\":\"10\",
                                            \"nilValue\": 300},
                                             \"name\":\"redTEST\"}