Class: LiveJournal::Database

Inherits:
Object
  • Object
show all
Defined in:
lib/livejournal/database.rb

Overview

An interface for an SQLite database dump.

Defined Under Namespace

Classes: Error

Constant Summary collapse

EXPECTED_DATABASE_VERSION = 
"3"
SCHEMA = 
%q{
CREATE TABLE meta (
  key TEXT PRIMARY KEY,
  value TEXT
);
CREATE TABLE entry (
  itemid INTEGER PRIMARY KEY,
  anum INTEGER,
  subject TEXT,
  event TEXT,
  moodid INTEGER, mood TEXT, music TEXT, location TEXT, taglist TEXT,
  pickeyword TEXT, preformatted INTEGER, backdated INTEGER,
  comments INTEGER, year INTEGER, month INTEGER, day INTEGER,
  timestamp INTEGER, security INTEGER
);
CREATE INDEX dateindex ON entry (year, month, day);
CREATE INDEX timeindex ON entry (timestamp);
CREATE TABLE comment (
  commentid INTEGER PRIMARY KEY,
  posterid INTEGER,
  itemid INTEGER,
  parentid INTEGER,
  state TEXT,  -- screened/deleted/frozen/active
  subject TEXT,
  body TEXT,
  timestamp INTEGER  -- unix timestamp
);
CREATE INDEX commententry ON comment (itemid);
CREATE TABLE users (
  userid INTEGER PRIMARY KEY,
  username TEXT
);
CREATE TABLE commentprop (
  commentid INTEGER,  -- not primary key 'cause non-unique
  key TEXT,
  value TEXT
);
}.gsub(/^      /, '')

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(filename, create_if_necessary = false) ⇒ Database

Returns a new instance of Database.

Raises:

  • (Errno::ENOENT) 


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# File 'lib/livejournal/database.rb', line 82

def initialize(filename, create_if_necessary=false)
  exists = FileTest::exists? filename
  raise Errno::ENOENT if not create_if_necessary and not exists
  @db = SQLite3::Database.new(filename)

  # We'd like to use type translation, but it unfortunately fails on MAX()
  # queries.
  # @db.type_translation = true

  if exists
    # Existing database!
    version = self.version
    unless version == EXPECTED_DATABASE_VERSION
      raise Error, "Database version mismatch -- db has #{version.inspect}, expected #{EXPECTED_DATABASE_VERSION.inspect}"
    end
  end

  if create_if_necessary and not exists
    # New database!  Initialize it.
    transaction do
      @db.execute_batch(SCHEMA)
    end
    self.version = EXPECTED_DATABASE_VERSION
  end
end

Instance Attribute Details

#db ⇒ Object (readonly)

The underlying SQLite3 database.



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# File 'lib/livejournal/database.rb', line 80

def db
  @db
end

Class Method Details

.db_value(name, sym) ⇒ Object

:nodoc:



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# File 'lib/livejournal/database.rb', line 125

def self.db_value(name, sym)  # :nodoc:
  class_eval %{def #{sym}; get_meta(#{name.inspect}); end}
  class_eval %{def #{sym}=(v); set_meta(#{name.inspect}, v); end}
end

.optional_to_i(x) ⇒ Object

:nodoc:



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# File 'lib/livejournal/database.rb', line 74

def self.optional_to_i(x) # :nodoc:
  return nil if x.nil?
  return x.to_i
end

Instance Method Details

#close ⇒ Object

Close the underlying database. (Is this necessary? Not sure.)



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# File 'lib/livejournal/database.rb', line 115

def close
  @db.close
end

#each_entry(where = nil, &block) ⇒ Object

Yield a set of entries, ordered by ascending itemid (first to last).



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# File 'lib/livejournal/database.rb', line 167

def each_entry(where=nil, &block)
  sql = 'SELECT * FROM entry'
  sql += " WHERE #{where}" if where
  sql += ' ORDER BY itemid ASC'
  query_entries sql, &block
end

#get_entry(itemid) ⇒ Object

Fetch a specific itemid.



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# File 'lib/livejournal/database.rb', line 149

def get_entry(itemid)
  query_entry("select * from entry where itemid=?", itemid)
end

#get_meta(key) ⇒ Object

:nodoc:



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# File 'lib/livejournal/database.rb', line 119

def get_meta key # :nodoc:
  return @db.get_first_value('SELECT value FROM meta WHERE key=?', key)
end

#journal ⇒ Object

The the actual journal stored by this Database. (This is different than simply the username when usejournal is specified.)



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# File 'lib/livejournal/database.rb', line 137

def journal
  usejournal || username
end

#last_comment_full ⇒ Object

Used for Sync::Comments.



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# File 'lib/livejournal/database.rb', line 191

def last_comment_full
  Database::optional_to_i(
      @db.get_first_value('SELECT MAX(commentid) FROM comment ' +
                          'WHERE body IS NOT NULL'))
end

#last_comment_meta ⇒ Object

Used for Sync::Comments.



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# File 'lib/livejournal/database.rb', line 186

def last_comment_meta
  Database::optional_to_i(
      @db.get_first_value('SELECT MAX(commentid) FROM comment'))
end

#query_entries(sql, *sqlargs) ⇒ Object

Given SQL that selects some entries, yield each Entry.



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# File 'lib/livejournal/database.rb', line 160

def query_entries(sql, *sqlargs) # :yields: entry
  @db.execute(sql, *sqlargs) do |row|
    yield Entry.new.load_from_database_row(row)
  end
end

#query_entry(sql, *sqlargs) ⇒ Object

Given SQL that selects an entry, return that Entry.



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# File 'lib/livejournal/database.rb', line 154

def query_entry(sql, *sqlargs)
  row = @db.get_first_row(sql, *sqlargs)
  return Entry.new.load_from_database_row(row)
end

#set_meta(key, value) ⇒ Object

:nodoc:



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# File 'lib/livejournal/database.rb', line 122

def set_meta key, value  # :nodoc:
  @db.execute('INSERT OR REPLACE INTO meta VALUES (?, ?)', key, value)
end

#store_comments_full(comments) ⇒ Object

Used for Sync::Comments.



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# File 'lib/livejournal/database.rb', line 202

def store_comments_full(comments)
  store_comments(comments, false)
end

#store_comments_meta(comments) ⇒ Object

Used for Sync::Comments.



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# File 'lib/livejournal/database.rb', line 198

def store_comments_meta(comments)
  store_comments(comments, true)
end

#store_entry(entry) ⇒ Object

Store an Entry.



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# File 'lib/livejournal/database.rb', line 180

def store_entry entry
  sql = 'INSERT OR REPLACE INTO entry VALUES (' + ("?, " * 17) + '?)'
  @db.execute(sql, *entry.to_database_row)
end

#store_usermap(usermap) ⇒ Object

Used for Sync::Comments.



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# File 'lib/livejournal/database.rb', line 207

def store_usermap(usermap)
  transaction do
    sql = "INSERT OR REPLACE INTO users VALUES (?, ?)"
    @db.prepare(sql) do |stmt|
      usermap.each do |id, user|
        stmt.execute(id, user)
      end
    end
  end
end

#total_entry_count ⇒ Object

Return the total number of entries.



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# File 'lib/livejournal/database.rb', line 175

def total_entry_count
  @db.get_first_value('SELECT COUNT(*) FROM entry').to_i
end

#trace! ⇒ Object

Turn tracing on. Mostly useful for debugging.



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# File 'lib/livejournal/database.rb', line 142

def trace!
  @db.trace() do |data, sql|
    puts "SQL> #{sql.inspect}"
  end
end

#transaction ⇒ Object

Run a block within a single database transaction. Useful for bulk inserts.



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# File 'lib/livejournal/database.rb', line 110

def transaction
  @db.transaction { yield }
end