2.2 KiB
What's New in Version 2
Python 3.5+ Only
This version of the ORM no longer support Python 2.
New flexible syntax for database expressions and functions
Expressions that use model fields, database functions and Python operators are now first-class citizens of the ORM. They provide infinite expressivity and flexibility when defining models and generating queries.
Example of expressions in model definition:
class Temperature(Model):
station_id = UInt16Field()
timestamp = DateTimeField(default=F.now()) # function as default value
degrees_celsius = Float32Field()
degrees_fahrenheit = Float32Field(alias=degrees_celsius * 1.8 + 32) # expression as field alias
# expressions in engine definition
engine = MergeTree(partition_key=[F.toYYYYMM(timestamp)], order_by=[station_id, timestamp])
Example of expressions in queries:
db = Database('default')
start = F.toStartOfMonth(F.now())
expr = (Temperature.timestamp > start) & (Temperature.station_id == 123) & (Temperature.degrees_celsius > 30)
for t in Temperature.objects_in(db).filter(expr):
print(t.timestamp, t.degrees_celsius)
See Expressions.
Support for IPv4 and IPv6 fields
Two new fields classes were added: IPv4Field and IPv6Field. Their values are represented by Python's ipaddress.IPv4Address and ipaddress.IPv6Address.
See Field Types.
Automatic generation of models by inspecting existing tables
It is now easy to generate a model class on the fly for an existing table in the database using Database.get_model_for_table. This is particularly useful for querying system tables, for example:
QueryLog = db.get_model_for_table('query_log', system_table=True)
for row in QueryLog.objects_in(db).filter(QueryLog.query_duration_ms > 10000):
print(row.query)
Convenient ways to import ORM classes
You can now import all ORM classes directly from infi.clickhouse_orm, without worrying about sub-modules. For example:
from infi.clickhouse_orm import Database, Model, StringField, DateTimeField, MergeTree