Implementation of a StaticValue class

[GregoirePelegrin]

Objective

I needed to generate the following SQL query:

SELECT CAST('some_constant' AS VARCHAR) "column_name" 
FROM "table"

I didn't seem to find any existing way to do it, so here is my proposal

StaticValue class

In pypika.terms

class StaticValue(Term):
    def __init__(self, value, alias: Optional[str] = None) -> None:
        super().__init__(alias)
        self._value = value

    def get_sql(self, **kwargs: Any) -> str:
        return format_alias_sql_new(self._value, self.alias, static_quote_char="'", **kwargs)

This class also introduces format_alias_sql_new() (in pypika.utils), which is an evolution of format_alias_sql() with an added static_quote_char parameter:

def format_alias_sql_new(
    sql: str, alias: Optional[str], quote_char: Optional[str] = None, alias_quote_char: Optional[str] = None,
    static_quote_char: Optional[str] = None, as_keyword: bool = False, **kwargs: Any,
) -> str:
    if alias is None:
        return format_quotes(value=sql, quote_char=static_quote_char)
    return "{sql}{_as}{alias}".format(
        sql=format_quotes(value=sql, quote_char=static_quote_char), _as=' AS ' if as_keyword else ' ',
        alias=format_quotes(alias, alias_quote_char or quote_char)
    )

format_quotes here being the normal pypika.utils.format_quotes.

[varunsinghal]

you may also try an alternative approach:

from pypika import Query, Table, functions as fn 

table = Table('my-table')
Query.from_(table).select('*', fn.LiteralValue("'some_constant'").as_("column_name"))