On Tue, Nov 6, 2018 at 6:11 PM 'Van Klaveren, Brian N.' via sqlalchemy
<sqlalchemy@googlegroups.com> wrote:
>
> Hi,
>
> I want to create a custom type for TINYINT and DOUBLE.
>
> I've defined them as custom types.
>
> I want to use with_variant for them, so that in sqlite they print out as
> TINYINT and DOUBLE.
>
> But I also want them to use the variants defined for other databases, like
> Oracle and Postgres.
>
> The first part works fine, the second part, not so much.
>
> What's really the best way to do this?
>
> Code is attached below.
>
> Brian
>
>
> from sqlalchemy.ext.compiler import compiles
> from sqlalchemy import SmallInteger, Float
> from sqlalchemy import types
> from sqlalchemy.dialects import mysql, oracle, postgresql
> from sqlalchemy import create_engine, MetaData, Column, Boolean
> from sqlalchemy.schema import Table
>
> MYSQL = "mysql"
> ORACLE = "oracle"
> POSTGRES = "postgresql"
> SQLITE = "sqlite"
>
> class TINYINT(SmallInteger):
> """The non-standard TINYINT type."""
> __visit_name__ = 'TINYINT'
>
>
> class DOUBLE(Float):
> """The non-standard DOUBLE type."""
> __visit_name__ = 'DOUBLE'
>
> @compiles(TINYINT)
> def compile_tinyint(type_, compiler, **kw):
> return "TINYINT"
>
>
> @compiles(DOUBLE)
> def compile_double(type_, compiler, **kw):
> return "DOUBLE"
>
> byte_map = {
> MYSQL: mysql.TINYINT(),
> ORACLE: oracle.NUMBER(3),
> POSTGRES: postgresql.SMALLINT(),
> }
>
> double_map = {
> MYSQL: mysql.DOUBLE(),
> ORACLE: oracle.BINARY_DOUBLE(),
> POSTGRES: postgresql.DOUBLE_PRECISION(),
> }
>
> def byte(**kwargs):
> return _vary(TINYINT(), byte_map, kwargs)
>
>
> def double(**kwargs):
> return _vary(DOUBLE(), double_map, kwargs)
>
> def _vary(type, variant_map, overrides):
> for dialect, variant in overrides.items():
> variant_map[dialect] = variant
> for dialect, variant in variant_map.items():
> type.with_variant(variant, dialect)
I think you need to reassign to type there, "type = type.with_variant(...)"
> return type
>
>
> metadata = MetaData()
>
> t = Table("MyTable", metadata,
> Column("my_byte", byte()),
> Column("my_double", double())
> )
>
>
> def metadata_dump(sql, *multiparams, **params):
> # print or write to log or file etc
> print(sql.compile(dialect=engine.dialect))
>
> engine = create_engine("sqlite://", strategy='mock', executor=metadata_dump)
> metadata.create_all(engine)
>
>
> def metadata_dump(sql, *multiparams, **params):
> # print or write to log or file etc
> print(sql.compile(dialect=engine.dialect))
>
> engine = create_engine("oracle://", strategy='mock', executor=metadata_dump)
> metadata.create_all(engine)
>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
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--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
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