def add_field(self, field_name, field_type, after=None, default=None):
"""Add a new field after the specified field, or in the beginning if
no field is specified"""
if field_name in self.field_names:
raise NameError, "Field %s already exists" % field_name
field_def = [field_name, field_type]
if default is not None:
field_def.append(default)
# validate field and update dictionary defaults
buzhug_info.validate_field(self, field_def)
if after is None:
indx = 2 # insert after __version__
elif not after in self.field_names:
raise NameError, "No field named %s" % after
else:
indx = 1 + self.field_names.index(after)
self.field_names.insert(indx, field_name)
self.fields[field_name] = field_type
# create field file
self._file[field_name] = \
self.file_types[self.fields[field_name]](self.name,field_name)
self._file[field_name].create()
# populate field file with default value and update position file
self._pos.add_field(field_name, indx, default)
buzhug_info.save_info(self)
self._full_rec = makeRecordClass(self, self.record_class,
self.field_names)
def create(self, *fields, **kw):
"""Creates a database instance and returns a reference to it
fields are tuples (field_name,field_type[,default_value])
field_name must not begin by _
field_type can be one of the values in the dictionary self.types
A keyword 'mode' can be specified:
'override' : if the base already exists, remove it and create
a new one
'open' : if the base already exists, open it
If mode is not set, if the base exists, raise IOError
In any case, if a directory of the same name exists, raise an
exception
"""
mode = kw.get('mode', None)
if os.path.exists(self.name):
if os.path.exists(self.info_name):
if mode == 'override':
pass
elif mode == 'open':
return self.open()
else:
raise IOError, "Base %s already exists" % self.name
else:
if mode != 'open':
raise IOError, "Directory %s already exists" % self.name
else:
raise IOError,"Mode 'open' : " \
"Directory %s already exists but no info file found" \
%self.name
self.field_names = [f[0] for f in fields]
self.fields = dict([(f[0], f[1]) for f in fields])
# set general info about field definition
buzhug_info.set_info(self, fields)
self.field_names = ['__id__', '__version__'] + self.field_names
self.fields['__id__'] = int
self.fields['__version__'] = int
# create the directory used for the base
if not os.path.exists(self.name):
os.mkdir(self.name)
# create index file
self._id_pos = IntegerFile(self.name, '_id_pos').create()
# create positions file
open(self.pos_name, 'wb').close()
self._pos = PositionFile(self).create()
# create the file holding a list of the deleted rows (the line number
# of deleted records in field files)
self._del_rows = DeletedRowsFile(self.name, "__del_rows__").create()
# create field files abstractions
self._file = {}
for f in self.field_names:
self._file[f] = self.file_types[self.fields[f]](self.name, f)
self._file[f].create()
# save information in files __info__ and __defaults__
buzhug_info.save_info(self)
# create class for records with all values set
self._full_rec = makeRecordClass(self, self.record_class,
self.field_names)
return self
def add_field(self,field_name,field_type,after=None,default=None):
"""Add a new field after the specified field, or in the beginning if
no field is specified"""
if field_name in self.field_names:
raise NameError,"Field %s already exists" %field_name
field_def = [field_name,field_type]
if default is not None:
field_def.append(default)
# validate field and update dictionary defaults
buzhug_info.validate_field(self,field_def)
if after is None:
indx = 2 # insert after __version__
elif not after in self.field_names:
raise NameError,"No field named %s" %after
else:
indx = 1+self.field_names.index(after)
self.field_names.insert(indx,field_name)
self.fields[field_name] = field_type
# create field file
self._file[field_name] = \
self.file_types[self.fields[field_name]](self.name,field_name)
self._file[field_name].create()
# populate field file with default value and update position file
self._pos.add_field(field_name,indx,default)
buzhug_info.save_info(self)
self._full_rec = makeRecordClass(self,self.record_class,
self.field_names)
def create(self,*fields,**kw):
"""Creates a database instance and returns a reference to it
fields are tuples (field_name,field_type[,default_value])
field_name must not begin by _
field_type can be one of the values in the dictionary self.types
A keyword 'mode' can be specified:
'override' : if the base already exists, remove it and create
a new one
'open' : if the base already exists, open it
If mode is not set, if the base exists, raise IOError
In any case, if a directory of the same name exists, raise an
exception
"""
mode = kw.get('mode',None)
if os.path.exists(self.name):
if os.path.exists(self.info_name):
if mode == 'override':
pass
elif mode == 'open':
return self.open()
else:
raise IOError,"Base %s already exists" %self.name
else:
if mode != 'open':
raise IOError,"Directory %s already exists" %self.name
else:
raise IOError,"Mode 'open' : " \
"Directory %s already exists but no info file found" \
%self.name
self.field_names = [ f[0] for f in fields ]
self.fields = dict([(f[0],f[1]) for f in fields])
# set general info about field definition
buzhug_info.set_info(self,fields)
self.field_names = ['__id__','__version__'] + self.field_names
self.fields['__id__'] = int
self.fields['__version__'] = int
# create the directory used for the base
if not os.path.exists(self.name):
os.mkdir(self.name)
# create index file
self._id_pos = IntegerFile(self.name,'_id_pos').create()
# create positions file
open(self.pos_name,'wb').close()
self._pos = PositionFile(self).create()
# create the file holding a list of the deleted rows (the line number
# of deleted records in field files)
self._del_rows = DeletedRowsFile(self.name,"__del_rows__").create()
# create field files abstractions
self._file = {}
for f in self.field_names:
self._file[f] = self.file_types[self.fields[f]](self.name,f)
self._file[f].create()
# save information in files __info__ and __defaults__
buzhug_info.save_info(self)
# create class for records with all values set
self._full_rec = makeRecordClass(self,self.record_class,self.field_names)
return self
def drop_field(self, field_name):
"""Remove the specified field name"""
if not field_name in self.field_names:
raise NameError, "No field named %s" % field_name
if field_name == '__id__':
raise ValueError, "Field __id__ can't be removed"
if field_name == '__version__':
raise ValueError, "Field __version__ can't be removed"
indx = self.field_names.index(field_name)
self.field_names.remove(field_name)
del self.defaults[field_name]
buzhug_info.save_info(self)
del self.fields[field_name]
del self._file[field_name]
self._pos.drop_field(field_name, indx)
self._full_rec = makeRecordClass(self, self.record_class,
self.field_names)
def drop_field(self,field_name):
"""Remove the specified field name"""
if not field_name in self.field_names:
raise NameError,"No field named %s" %field_name
if field_name == '__id__':
raise ValueError,"Field __id__ can't be removed"
if field_name == '__version__':
raise ValueError,"Field __version__ can't be removed"
indx = self.field_names.index(field_name)
self.field_names.remove(field_name)
del self.defaults[field_name]
buzhug_info.save_info(self)
del self.fields[field_name]
del self._file[field_name]
self._pos.drop_field(field_name,indx)
self._full_rec = makeRecordClass(self,self.record_class,
self.field_names)
