Class: SafeDb::DataStore

Inherits:
Hash
  • Object
show all
Defined in:
lib/utils/store/datastore.rb

Overview

A Key/Value database knows how to manipulate a JSON backend data structure (put, add etc) after reading and then decrypting it from a file and before encrypting and then writing it to a file.

Difference Between DataStore and DataStore

The DataStore is a JSON backed store that streams to and from INI formatted data. The DataStore is preferred for human readable data which is precisely 2 dimensional. The streamed DataMap is JSON which at scale isn’t human readable but the data structure is N dimensional and it supports nested structures such as lists, maps, numbers and booleans.

It provides behaviour to which we can create, append (add), update (change), read parts and delete essentially two structures

  • a collection of name/value pairs

  • an ordered list of values

JSON is Not Exposed in the Interface

A key/value database doesn’t expose the data format used in the implementation allowing this to be changed seamlessly to YAMl or other formats.

Symmetric Encryption and Decryption

A key/value database supports operations to read from and write to a known filepath and with a symmetric key it can

  • decrypt after reading from a file and

  • encrypt before writing to a (the same) file

Hashes as the Primary Data Structure

The key/value database openly extends Hash as the data structure for holding

  • strings

  • arrays

  • other hashes

  • booleans

  • integers and floats

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Hash

#log_contents, #merge_recursively!, #reject_message

Class Method Details

.from_json(db_json_string) ⇒ DataStore

Return a key database data structure that is instantiated from the parameter JSON string.

Parameters:

  • db_json_string (String) —

    this json formatted data structure will be converted into a a Ruby hash (map) data structure and returned.

Returns:

  • (DataStore) —

    a hash data structure that has been instantiated as per the parameter json string content.



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# File 'lib/utils/store/datastore.rb', line 62

def self.from_json( db_json_string )

  data_db = DataStore.new()
  data_db.merge!( JSON.parse( db_json_string ) )
  return data_db

end

Instance Method Details

#create_entry(dictionary_name, key_name, value) ⇒ Object

Create a new key value entry inside a dictionary with the specified name at the root of this database. Successful completion means the named dictionary will contain one more entry than it need even if it did not previously exist.

Parameters:

  • dictionary_name (String) —

    if a dictionary with this name exists at the root of the database add the parameter key value pair into it.

    if no dictionary exists then create one first before adding the key value pair as the first entry into it.

  • key_name (String) —

    the key part of the key value pair that will be added into the dictionary whose name was provided in the first parameter.

  • value (String) —

    the value part of the key value pair that will be added into the dictionary whose name was provided in the first parameter.



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# File 'lib/utils/store/datastore.rb', line 119

def create_entry( dictionary_name, key_name, value )

  KeyError.not_new( dictionary_name, self )
  KeyError.not_new( key_name, self )
  KeyError.not_new( value, self )

  self[ dictionary_name ] = {} unless self.has_key?( dictionary_name )
  self[ dictionary_name ][ key_name ] = value

end

#create_map_entry(outer_keyname, inner_keyname, entry_keyname, entry_value) ⇒ Object

Create a new secondary tier map key value entry inside a primary tier map at the map_key_name location.

A failure will occur if either the outer or inner keys already exist without their values being map objects.

If this method is called against a new empty map, the resulting map structure will look like the below.

{ outer_keyname ~> { inner_keyname ~> { entry_keyname, entry_value } } }

Parameters:

  • outer_keyname (String) —

    if a dictionary with this name exists at the root of the database add the parameter key value pair into it.

    if no dictionary exists then create one first before adding the key value pair as the first entry into it.

  • inner_keyname (String) —

    if a map exists at this key name then an entry comprising of a map_entry_key and a entry_value may either be added (if the map_entry_key does not already exist), or updated if it does.

    if the map does not exist it will be created and its first and only entry will be a key with inner_keyname along with a new single entry map consisting of the entry_keyname and the entry_value.

  • entry_keyname (String) —

    this key will exist in the second tier map after this operation.

  • entry_value (String) —

    this value will exist in the second tier map after this operation and if the entry_keyname already existed its value is overwritten with this one.



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# File 'lib/utils/store/datastore.rb', line 172

def create_map_entry( outer_keyname, inner_keyname, entry_keyname, entry_value )

  KeyError.not_new( outer_keyname, self )
  KeyError.not_new( inner_keyname, self )
  KeyError.not_new( entry_keyname, self )
  KeyError.not_new( entry_value,   self )

  self[ outer_keyname ] = {} unless self.has_key?( outer_keyname )
  self[ outer_keyname ][ inner_keyname ] = {} unless self[ outer_keyname ].has_key?( inner_keyname )
  self[ outer_keyname ][ inner_keyname ][ entry_keyname ] = entry_value

end

#delete_entry(dictionary_name, key_name) ⇒ Object

Delete an existing key value entry inside the dictionary with the specified name at the root of this database. Successful completion means the named dictionary will contain one less entry if that key existed.

Parameters:

  • dictionary_name (String) —

    if a dictionary with this name exists at the root of the database add the parameter key value pair into it.

    if no dictionary exists throw an error

  • key_name (String) —

    the key part of the key value pair that will be deleted in the dictionary whose name was provided in the first parameter.



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# File 'lib/utils/store/datastore.rb', line 251

def delete_entry( dictionary_name, key_name )

  KeyError.not_new( dictionary_name, self )
  KeyError.not_new( key_name, self )

  self[ dictionary_name ].delete( key_name )

end

#get_entry(dictionary_name, key_name) ⇒ Object

Get the entry with the key name in a dictionary that is itself inside another dictionary (named in the first parameter) which thankfully is at the root of this database.

Only call this method if #has_entry? returns true for the same dictionary and key name parameters.

Parameters:

  • dictionary_name (String) —

    get the entry inside a dictionary which is itself inside a dictionary (with this dictionary name) which is itself at the root of this database.

  • key_name (String) —

    get the value part of the key value pair that is inside a dictionary (with the above dictionary name) which is itself at the root of this database.



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# File 'lib/utils/store/datastore.rb', line 229

def get_entry( dictionary_name, key_name )

  return self[ dictionary_name ][ key_name ]

end

#has_entry?(dictionary_name, key_name) ⇒ Boolean

Does this database have an entry in the root dictionary named with the key_name parameter?

Parameters:

  • dictionary_name (String) —

    immediately return false if a dictionary with this name does not exist at the root of this database.

  • key_name (String) —

    test whether a key/value pair answering to this name exists inside the specified dictionary at the root of this database.

Returns:

  • (Boolean) 


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# File 'lib/utils/store/datastore.rb', line 199

def has_entry?( dictionary_name, key_name )

  KeyError.not_new( dictionary_name, self )
  KeyError.not_new( key_name, self )

  return false unless self.has_key?( dictionary_name )
  return self[ dictionary_name ].has_key?( key_name )

end

#set(key_name, key_value) ⇒ Object

Stash the setting directive and its value into the configuration file using the default settings group.

Parameters:

  • key_name (String) —

    the name of the key whose value is to be written

  • key_value (String) —

    the data item value of the key specified

Raises:

  • (ArgumentError) 


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# File 'lib/utils/store/datastore.rb', line 88

def set key_name, key_value
  raise ArgumentError, "Cannot set a Nil (section)" if @section.nil?
  raise ArgumentError, "Cannot set a Nil key name." if key_name.nil?
  raise ArgumentError, "Cannot set a Nil key value" if key_value.nil?
  create_entry( @section, key_name, key_value )
end

#use(section) ⇒ Object

Set the section to use for future data exchanges via the ubiquitous get and #set methods as well as the query contains key method.

Parameters:

  • section (String) —

    the non-nil and non whitespace only section name that will lead a set of key-value pairs in the INI formatted file.

Raises:

  • (ArgumentError) 


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# File 'lib/utils/store/datastore.rb', line 77

def use section
  raise ArgumentError, "Cannot use a Nil section." if section.nil?
  @section = section
end