Python shelve module

Shelve module

Shelve is similar to a key-value database, which can be conveniently used to hold Python's memory objects, using pickle to serialize data internally, and simply, users can save a list, dictionary, or user-defined class instance to shelve. The next time you need to use it, just take it out, it's a Python memory object.

Use Example 1

Import Shelvezhang = Dict ([' Name ', ' age '], [' Zhang ',])) Li = Dict ([' Name ', ' age '], [' Li ', 15]) # Store object to file db = She Lve.open (' shelvedict.db ')  # Open a file db[' zhang ' = Zhang  # Add content to the file, add the same as the key value pair to the dictionary db[' li ') = Lidb.close ()  # Close File # Extract object from File db = Shelve.open (' shelvedict.db ')  # Open a file print (db[' Zhang ')  # Read the same as the key obtained from the dictionary {' name ': ' Zhang ', ' Age ': 14}print (db[' li ')  # results for {' age ': ' name ': ' li '}# extract the object from the file and modify the db = Shelve.open (' shelvedict.db ')  # Open File Zhang_obj = db[' Zhang ')  # Read the previously stored object from the file zhang_obj[' name '] = ' Zi '  # directly modify the object zhang_obj[' age ' = 24db[' Zhang '] = zhang_obj  # re-stored in the dictionary file object in print (db[' Zhang ')  # The result is as follows {' Age ': ' ' name ': ' Zi '}db.close ()

　

Use Example 2

Import Shelveclass Shelveutil (object): "" "    use shelve store to extract Object" ""    def __init__ (self, file):        Self.file_obj = Shelve.open (file)    def save (self, Key, value): "" "         Storage object        :p Aram key:        :p Aram value:< C10/>:return: "" "        Self.file_obj[key] = value    def load (self, key):" "         gets object        :p Aram Key :        : Return:        "" "        return Self.file_obj[key]        def __del__ (self):        self.file_obj.close () if __ name__ = = ' __main__ ':    a = {' A ': 1, ' B ': 2}    s = Shelveutil (' a.db ')    s.save (' A ', a)    print (S.load (' a '))

　　

　　

　

Python shelve module