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import sqlalchemy as sa
from sqlalchemy.dialects import postgresql
from sqlalchemy.ext.compiler import compiles
from sqlalchemy.sql.expression import ColumnElement, FunctionElement
from sqlalchemy.sql.functions import GenericFunction
from .functions.orm import quote
class array_get(FunctionElement):
name = 'array_get'
@compiles(array_get)
def compile_array_get(element, compiler, **kw):
args = list(element.clauses)
if len(args) != 2:
raise Exception(
"Function 'array_get' expects two arguments (%d given)." % len(args)
)
if not hasattr(args[1], 'value') or not isinstance(args[1].value, int):
raise Exception('Second argument should be an integer.')
return f'({compiler.process(args[0])})[{sa.text(str(args[1].value + 1))}]'
class row_to_json(GenericFunction):
name = 'row_to_json'
type = postgresql.JSON
@compiles(row_to_json, 'postgresql')
def compile_row_to_json(element, compiler, **kw):
return f'{element.name}({compiler.process(element.clauses)})'
class json_array_length(GenericFunction):
name = 'json_array_length'
type = sa.Integer
@compiles(json_array_length, 'postgresql')
def compile_json_array_length(element, compiler, **kw):
return f'{element.name}({compiler.process(element.clauses)})'
class Asterisk(ColumnElement):
def __init__(self, selectable):
self.selectable = selectable
@compiles(Asterisk)
def compile_asterisk(element, compiler, **kw):
return '%s.*' % quote(compiler.dialect, element.selectable.name)
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