how to add constant column in Pypika

Question

I ran into trouble. I've read through manual to pypika and I haven't found out, how to define constant column.

E.g.

SELECT t.id, 
       'constant' as constant_variable 
     FROM example_table t

I've tried using PseudoColumn, but it didn't work for me.

car = PseudoColumn('CAR') 

   query = Query \
        .from_('test_table') \
        .select(car) 
print(query)

The result is

SELECT CAR FROM "test_table"

Instead of

SELECT 'CAR' FROM "test_table"

Answer 1

One of the ways to do it is to use ValueWrapper from pypika.terms. Same as in example above, but instead of PseudoColumn('CAR') use ValueWrapper('CAR', 'alias').

from pypika.terms import ValueWrapper
car = ValueWrapper('CAR', 'car') 

query = Query \
        .from_('test_table') \
        .select(car)