Flask中使用SqlAlchemy的较好方法
首先安装 Flask-SqlAlchem??v0.15 和?SqlAutoCode??v0.7
在配置文件settings中设置
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SQLALCHEMY_DATABASE_URI = 'mysql://kw3:123456@localhost/kw3_article'SQLALCHEMY_BINDS = { 'game': 'mysql://kw3:123456@localhost/kw_game',}TABLE_PREFIX = 't_'?
?将最后面的代码放到scripts下，并运行它。 ?如存为generate_models.py文件，python ?scripts/generate_models.py
在项目入口文件中
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#-*- coding: utf-8 -*-from flask import Flaskfrom models.base.db import dbapp = Flask(__name__)db.init_app(app)
?你就可以在view中使用了，具体参考??http://packages.python.org/Flask-SQLAlchemy/index.html
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自动产生models的脚本:
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#-*- coding: utf-8 -*-#使用SqlAutocode，根据数据库已有表，产生符合Flask-SqlAlchemy要求的models的定义import os.pathfrom flask import Flaskfrom sqlautocode import configfrom sqlautocode.declarative import *from sqlautocode.formatter import _repr_coltype_asfrom flask.ext.sqlalchemy import SQLAlchemysingular = plural = lambda x: xconstants.COLUMN = 'db.' + constants.COLUMNconstants.HEADER_DECL = """from sqlalchemy import *if __name__ == '__main__': from flask import Flask from flask.ext.sqlalchemy import SQLAlchemy app = Flask(__name__) app.config['SQLALCHEMY_DATABASE_URI'] = '%s' db = SQLAlchemy(app)else: from .db import db"""def no_prefix_wrapper(f, prefix=None): def _name2label(name, schema=None): if schema: if name.startswith(schema+'.'): name = '.'.join(name.split('.')[1:]) if prefix and name.startswith(prefix): name = name[ len(prefix):] label = str(''.join([s.capitalize() for s in re.findall(r'([A-Z][a-z0-9]+|[a-z0-9]+|[A-Z0-9]+)', name)])) return label return _name2labeldef column_repr(self): kwarg = [] if self.key != self.name: kwarg.append( 'key') if hasattr(self, 'primary_key') and self.primary_key: self.primary_key = True kwarg.append( 'primary_key') if not self.nullable: kwarg.append( 'nullable') if self.onupdate: kwarg.append( 'onupdate') if self.default: kwarg.append( 'default') ks = ', '.join('%s=%r' % (k, getattr(self, k)) for k in kwarg) if self.server_default: ks += ', ' if ks else '' ks += ('default=%s' % self.server_default.arg.text) name = self.name if not hasattr(config, 'options') and self.config.options.generictypes: coltype = repr(self.type) elif type(self.type).__module__ == 'sqlalchemy.types': coltype = repr(self.type) else: # Try to 'cast' this column type to a cross-platform type # from sqlalchemy.types, dropping any database-specific type # arguments. for base in type(self.type).__mro__: if (base.__module__ == 'sqlalchemy.types' and base.__name__ in sqlalchemy.__all__): coltype = _repr_coltype_as(self.type, base) break # FIXME: if a dialect has a non-standard type that does not # derive from an ANSI type, there's no choice but to ignore # generic-types and output the exact type. However, import # headers have already been output and lack the required # dialect import. else: coltype = repr(self.type) data = {'name': self.name, 'type': coltype, 'constraints': ', '.join(["ForeignKey('%s')"%cn.target_fullname for cn in self.foreign_keys]), 'args': ks and ks or '', } if data['constraints']: if data['constraints']: data['constraints'] = ', ' + data['constraints'] if data['args']: if data['args']: data['args'] = ', ' + data['args'] return constants.COLUMN % dataclass FlaskModelFactory(ModelFactory): def __init__(self, name, conn): self.name = name argv = ['sqlautocode', conn, '-d', '-g', '-i'] config.configure(argv) config.interactive, config.schema, config.example = None, None, False super(FlaskModelFactory, self).__init__(config) def _table_repr(self, table): s = "db.Table(u'%s',\n"%(table.name) for column in table.c: s += " %s,\n"%column_repr(column) if self.name != "default": s +=" info={'bind_key': '%s'}\n"%self.name #if table.schema: # s +=" schema='%s'\n"%table.schema s+=")" return s def create_model(self, table): #partially borrowed from Jorge Vargas' code #http://dpaste.org/V6YS/ log.debug('Creating Model from table: %s'%table.name) model_name = self.find_new_name(singular(name2label(table.name)), self.used_model_names) self.used_model_names.append(model_name) is_many_to_many_table = self.is_many_to_many_table(table) table_name = self.find_new_name(table.name, self.used_table_names) self.used_table_names.append(table_name) mtl = self.model_table_lookup class Temporal(self.DeclarativeBase): __table__ = table @classmethod def _relation_repr(cls, rel): target = rel.argument if target and inspect.isfunction(target): target = target() if isinstance(target, Mapper): target = target.class_ target = target.__name__ primaryjoin='' lookup = mtl() if rel.primaryjoin is not None and hasattr(rel.primaryjoin, 'right'): right_lookup = lookup.get(rel.primaryjoin.right.table.name, '%s.c'%rel.primaryjoin.right.table.name) left_lookup = lookup.get(rel.primaryjoin.left.table.name, '%s.c'%rel.primaryjoin.left.table.name) primaryjoin = ", primaryjoin='%s.%s==%s.%s'"%(left_lookup, rel.primaryjoin.left.name, right_lookup, rel.primaryjoin.right.name) elif hasattr(rel, '_as_string'): primaryjoin=', primaryjoin="%s"'%rel._as_string secondary = '' secondaryjoin = '' if rel.secondary is not None: secondary = ", secondary=%s"%rel.secondary.name right_lookup = lookup.get(rel.secondaryjoin.right.table.name, '%s.c'%rel.secondaryjoin.right.table.name) left_lookup = lookup.get(rel.secondaryjoin.left.table.name, '%s.c'%rel.secondaryjoin.left.table.name) secondaryjoin = ", secondaryjoin='%s.%s==%s.%s'"%(left_lookup, rel.secondaryjoin.left.name, right_lookup, rel.secondaryjoin.right.name) backref=''# if rel.backref:# backref=", backref='%s'"%rel.backref.key return "%s = relation('%s'%s%s%s%s)"%(rel.key, target, primaryjoin, secondary, secondaryjoin, backref) @classmethod def __repr__(cls): try: mapper = None try: mapper = class_mapper(cls) except exc.InvalidRequestError: log.warn("A proper mapper could not be generated for the class %s, no relations will be created"%model_name) s = "" s += "class "+model_name+'(db.Model):\n' if cls.__bind_key__ != "default": s += " __bind_key__ = '%s'\n"%cls.__bind_key__ if is_many_to_many_table: s += " __table__ = %s\n\n"%table_name else: s += " __tablename__ = '%s'\n"%table_name if hasattr(cls, '__table_args__'): #if cls.__table_args__[0]: #for fkc in cls.__table_args__[0]: # fkc.__class__.__repr__ = foreignkeyconstraint_repr # break s+=" __table_args__ = %s\n"%cls.__table_args__ s+="\n" for column in cls.__table__.c: s += " %s = %s\n"%(column.name, column_repr(column)) ess = s # this is only required in SA 0.5 if mapper and RelationProperty: for prop in mapper.iterate_properties: if isinstance(prop, RelationshipProperty): s+=' %s\n'%cls._relation_repr(prop) return s except Exception, e: log.error("Could not generate class for: %s"%cls.__name__) from traceback import format_exc log.error(format_exc()) return '' #hack the class to have the right classname Temporal.__name__ = model_name #set up some blank table args Temporal.__table_args__ = {} #add in the schema Temporal.__bind_key__ = self.name #if self.config.schema: # Temporal.__table_args__[1]['schema'] = table.schema #trick sa's model registry to think the model is the correct name if model_name != 'Temporal': Temporal._decl_class_registry[model_name] = Temporal._decl_class_registry['Temporal'] del Temporal._decl_class_registry['Temporal'] #add in single relations fks = self.get_single_foreign_keys_by_column(table) for column, fk in fks.iteritems(): related_table = fk.column.table if related_table not in self.tables: continue log.info(' Adding <primary> foreign key for:%s'%related_table.name) backref_name = plural(table_name) rel = relation(singular(name2label(related_table.name, related_table.schema)), primaryjoin=column==fk.column)#, backref=backref_name) setattr(Temporal, related_table.name, _deferred_relationship(Temporal, rel)) #add in the relations for the composites for constraint in table.constraints: if isinstance(constraint, ForeignKeyConstraint): if len(constraint.elements) >1: related_table = constraint.elements[0].column.table related_classname = singular(name2label(related_table.name, related_table.schema)) primary_join = "and_(%s)"%', '.join(["%s.%s==%s.%s"%(model_name, k.parent.name, related_classname, k.column.name) for k in constraint.elements]) rel = relation(related_classname, primaryjoin=primary_join #foreign_keys=[k.parent for k in constraint.elements] ) rel._as_string = primary_join setattr(Temporal, related_table.name, rel) # _deferred_relationship(Temporal, rel)) #add in many-to-many relations for join_table in self.get_related_many_to_many_tables(table.name): if join_table not in self.tables: continue primary_column = [c for c in join_table.columns if c.foreign_keys and list(c.foreign_keys)[0].column.table==table][0] for column in join_table.columns: if column.foreign_keys: key = list(column.foreign_keys)[0] if key.column.table is not table: related_column = related_table = list(column.foreign_keys)[0].column related_table = related_column.table if related_table not in self.tables: continue log.info(' Adding <secondary> foreign key(%s) for:%s'%(key, related_table.name)) setattr(Temporal, plural(related_table.name), _deferred_relationship(Temporal, relation(singular(name2label(related_table.name, related_table.schema)), secondary=join_table, primaryjoin=list(primary_column.foreign_keys)[0].column==primary_column, secondaryjoin=column==related_column ))) break; return Temporaldef gen_models_dir(app, models_dir): #找到并建立models文件夹和__init__.py文件 if not models_dir: app_root = app.config.get('APPLICATION_ROOT', '') if not app_root: app_root = os.path.dirname( os.path.dirname( os.path.realpath(__file__) ) ) models_dir = os.path.join(app_root, 'models') if not os.path.exists(models_dir): os.mkdir(models_dir) init_file = os.path.join(models_dir, '__init__.py') with open(init_file, 'wb') as fh: fh.write('#-*- coding: utf-8 -*-\n') return models_dirdef write_db_file(db_file): #建立数据库定义文件 with open(db_file, 'wb') as fh: fh.write('#-*- coding: utf-8 -*-\n') fh.write('\n') fh.write('from flask.ext.sqlalchemy import SQLAlchemy\n') fh.write('\n\n') fh.write('db = SQLAlchemy()\n')def write_schema_file(factory, schema_file, name='default'): #建立数据库定义文件 with open(schema_file, 'wb') as fh: fh.write("#-*- coding: utf-8 -*-\n") fh.write('\n') fh.write( repr(factory) ) fh.write('\n') fh.write("if __name__ == '__main__':\n") if name == 'default': fh.write(" db.create_all(bind=None)\n") else: fh.write(" db.create_all(bind=['%s'])\n" % name)def generate_models(app, models_dir=None): db = SQLAlchemy(app) conns = { 'default': app.config.get('SQLALCHEMY_DATABASE_URI') or {}, } conns.update( app.config.get('SQLALCHEMY_BINDS') or {} ) models_dir = gen_models_dir(app, models_dir) db_file = os.path.join(models_dir, 'db.py') if not os.path.exists(db_file): write_db_file(db_file) for name, conn in conns.items(): if not conn: continue schema_file = os.path.join(models_dir, '%s.py' % name) if not os.path.exists(schema_file): factory = FlaskModelFactory(name, conn) write_schema_file(factory, schema_file, name)if __name__ == '__main__': import sys sys.path.append( os.path.dirname( os.path.dirname( os.path.realpath(__file__) ) ) ) app = Flask(__name__) app.config.from_object('settings') name2label = no_prefix_wrapper(name2label, app.config.get('TABLE_PREFIX')) generate_models(app)