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Mini Shell
Mini Shell
from collections import Hashable, OrderedDict
import peewee as pw
from playhouse.reflection import Column as VanilaColumn
INDENT = ' '
NEWLINE = '\n' + INDENT
def fk_to_params(field):
params = {}
if field.on_delete is not None:
params['on_delete'] = field.on_delete
if field.on_update is not None:
params['on_update'] = field.on_update
return params
FIELD_TO_PARAMS = {
pw.CharField: lambda f: {'max_length': f.max_length},
pw.DecimalField: lambda f: {
'max_digits': f.max_digits, 'decimal_places': f.decimal_places,
'auto_round': f.auto_round, 'rounding': f.rounding},
pw.ForeignKeyField: fk_to_params,
}
class Column(VanilaColumn):
def __init__(self, field, migrator=None): # noqa
self.name = field.name
self.field_class = type(field)
self.nullable = field.null
self.primary_key = field.primary_key
self.db_column = field.db_column
self.index = field.index
self.unique = field.unique
self.params = {}
if field.default is not None and not callable(field.default):
self.params['default'] = field.default
if self.field_class in FIELD_TO_PARAMS:
self.params.update(FIELD_TO_PARAMS[self.field_class](field))
self.rel_model = None
self.related_name = None
self.to_field = None
if isinstance(field, pw.ForeignKeyField):
self.to_field = field.to_field.name
if migrator and field.rel_model._meta.name in migrator.orm:
self.rel_model = "migrator.orm['%s']" % field.rel_model._meta.name
else:
self.rel_model = field.rel_model.__name__
def get_field_parameters(self):
params = super(Column, self).get_field_parameters()
params.update({k: repr(v) for k, v in self.params.items()})
return params
def get_field(self, space=' '):
# Generate the field definition for this column.
field_params = self.get_field_parameters()
param_str = ', '.join('%s=%s' % (k, v)
for k, v in sorted(field_params.items()))
return '{name}{space}={space}pw.{classname}({params})'.format(
name=self.name, space=space, classname=self.field_class.__name__, params=param_str)
def diff_one(model1, model2, **kwargs):
"""Find difference between Peewee models."""
changes = []
fields1 = model1._meta.fields
fields2 = model2._meta.fields
# Add fields
names1 = set(fields1) - set(fields2)
if names1:
fields = [fields1[name] for name in names1]
changes.append(create_fields(model1, *fields, **kwargs))
# Drop fields
names2 = set(fields2) - set(fields1)
if names2:
changes.append(drop_fields(model1, *names2))
# Change fields
fields_ = []
nulls_ = []
for name in set(fields1) - names1 - names2:
field1, field2 = fields1[name], fields2[name]
diff = compare_fields(field1, field2)
null = diff.pop('null', None)
if diff:
fields_.append(field1)
if null is not None:
nulls_.append((name, null))
if fields_:
changes.append(change_fields(model1, *fields_, **kwargs))
for name, null in nulls_:
changes.append(change_not_null(model1, name, null))
return changes
def diff_many(models1, models2, migrator=None, reverse=False):
models1 = pw.sort_models_topologically(models1)
models2 = pw.sort_models_topologically(models2)
if reverse:
models1 = reversed(models1)
models2 = reversed(models2)
models1 = OrderedDict([(m._meta.name, m) for m in models1])
models2 = OrderedDict([(m._meta.name, m) for m in models2])
changes = []
# Add models
for name in [m for m in models1 if m not in models2]:
changes.append(create_model(models1[name], migrator=migrator))
# Remove models
for name in [m for m in models2 if m not in models1]:
changes.append(remove_model(models2[name]))
for name, model1 in models1.items():
if name not in models2:
continue
changes += diff_one(model1, models2[name], migrator=migrator)
return changes
def model_to_code(Model, **kwargs):
template = """class {classname}(pw.Model):
{fields}
"""
fields = INDENT + NEWLINE.join([
field_to_code(field, **kwargs) for field in Model._meta.sorted_fields
if not (isinstance(field, pw.PrimaryKeyField) and field.name == 'id')
])
return template.format(
classname=Model.__name__,
fields=fields
)
def create_model(Model, **kwargs):
return '@migrator.create_model\n' + model_to_code(Model, **kwargs)
def remove_model(Model, **kwargs):
return "migrator.remove_model('%s')" % Model._meta.db_table
def create_fields(Model, *fields, **kwargs):
return "migrator.add_fields(%s'%s', %s)" % (
NEWLINE,
Model._meta.db_table,
NEWLINE + (',' + NEWLINE).join([field_to_code(field, False, **kwargs) for field in fields])
)
def drop_fields(Model, *fields, **kwargs):
return "migrator.remove_fields('%s', %s)" % (
Model._meta.db_table, ', '.join(map(repr, fields))
)
def field_to_code(field, space=True, **kwargs):
col = Column(field, **kwargs)
return col.get_field(' ' if space else '')
def compare_fields(field1, field2, **kwargs):
field_cls1, field_cls2 = type(field1), type(field2)
if field_cls1 != field_cls2: # noqa
return {'cls': True}
params1 = field_to_params(field1)
params1['null'] = field1.null
params2 = field_to_params(field2)
params2['null'] = field2.null
return dict(set(params1.items()) - set(params2.items()))
def field_to_params(field, **kwargs):
params = FIELD_TO_PARAMS.get(type(field), lambda f: {})(field)
if field.default is not None and \
not callable(field.default) and \
isinstance(field.default, Hashable):
params['default'] = field.default
return params
def change_fields(Model, *fields, **kwargs):
return "migrator.change_fields('%s', %s)" % (
Model._meta.db_table, (',' + NEWLINE).join([field_to_code(f, False) for f in fields])
)
def change_not_null(Model, name, null):
operation = 'drop_not_null' if null else 'add_not_null'
return "migrator.%s('%s', %s)" % (operation, Model._meta.db_table, repr(name))
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