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from sqlglot import expressions as exp
def unalias_group(expression):
"""
Replace references to select aliases in GROUP BY clauses.
Example:
>>> import sqlglot
>>> sqlglot.parse_one("SELECT a AS b FROM x GROUP BY b").transform(unalias_group).sql()
'SELECT a AS b FROM x GROUP BY 1'
"""
if isinstance(expression, exp.Group) and isinstance(expression.parent, exp.Select):
aliased_selects = {
e.alias: i for i, e in enumerate(expression.parent.expressions, start=1) if isinstance(e, exp.Alias)
}
expression = expression.copy()
for col in expression.find_all(exp.Column):
alias_index = aliased_selects.get(col.name)
if not col.table and alias_index:
col.replace(exp.Literal.number(alias_index))
return expression
def preprocess(transforms, to_sql):
"""
Create a new transform function that can be used a value in `Generator.TRANSFORMS`
to convert expressions to SQL.
Args:
transforms (list[(exp.Expression) -> exp.Expression]):
Sequence of transform functions. These will be called in order.
to_sql ((sqlglot.generator.Generator, exp.Expression) -> str):
Final transform that converts the resulting expression to a SQL string.
Returns:
(sqlglot.generator.Generator, exp.Expression) -> str:
Function that can be used as a generator transform.
"""
def _to_sql(self, expression):
expression = transforms[0](expression)
for t in transforms[1:]:
expression = t(expression)
return to_sql(self, expression)
return _to_sql
def delegate(attr):
"""
Create a new method that delegates to `attr`.
This is useful for creating `Generator.TRANSFORMS` functions that delegate
to existing generator methods.
"""
def _transform(self, *args, **kwargs):
return getattr(self, attr)(*args, **kwargs)
return _transform
UNALIAS_GROUP = {exp.Group: preprocess([unalias_group], delegate("group_sql"))}
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