Class: SQLite3::Database

Inherits:
Object
  • Object
show all
Includes:
Fiddle, Pragmas
Defined in:
lib/sqlite3/database.rb

Defined Under Namespace

Classes: FunctionProxy

Constant Summary collapse

OPEN_READONLY =

Ok for sqlite3_open_v2()

0x00000001
OPEN_READWRITE =

Ok for sqlite3_open_v2()

0x00000002
OPEN_CREATE =

Ok for sqlite3_open_v2()

0x00000004
OPEN_DELETEONCLOSE =

VFS only

0x00000008
OPEN_EXCLUSIVE =

VFS only

0x00000010
OPEN_AUTOPROXY =

VFS only

0x00000020
OPEN_URI =

Ok for sqlite3_open_v2()

0x00000040
OPEN_MEMORY =

Ok for sqlite3_open_v2()

0x00000080
OPEN_MAIN_DB =

VFS only

0x00000100
OPEN_TEMP_DB =

VFS only

0x00000200
OPEN_TRANSIENT_DB =

VFS only

0x00000400
OPEN_MAIN_JOURNAL =

VFS only

0x00000800
OPEN_TEMP_JOURNAL =

VFS only

0x00001000
OPEN_SUBJOURNAL =

VFS only

0x00002000
OPEN_MASTER_JOURNAL =

VFS only

0x00004000
OPEN_NOMUTEX =

Ok for sqlite3_open_v2()

0x00008000
OPEN_FULLMUTEX =

Ok for sqlite3_open_v2()

0x00010000
OPEN_SHAREDCACHE =

Ok for sqlite3_open_v2()

0x00020000
OPEN_PRIVATECACHE =

Ok for sqlite3_open_v2()

0x00040000
OPEN_WAL =

VFS only

0x00080000
SQLITE_UTF8 = 
1
FUNC_PARAMS = 
[TYPE_VOIDP, TYPE_INT, TYPE_VOIDP].freeze
TRACE_PARAMS = 
[TYPE_VOIDP, TYPE_VOIDP].freeze
AUTH_PARAMS = 
[
  TYPE_VOIDP, TYPE_INT, TYPE_VOIDP, TYPE_VOIDP, TYPE_VOIDP, TYPE_VOIDP
].freeze
COLLATION_PARAMS = 
[
  TYPE_VOIDP, TYPE_INT, TYPE_VOIDP, TYPE_INT, TYPE_VOIDP
].freeze
BUSY_PARAMS = 
[TYPE_VOIDP, TYPE_INT].freeze

Constants included from Pragmas

Pragmas::SYNCHRONOUS_MODES, Pragmas::TEMP_STORE_MODES

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Pragmas

#auto_vacuum, #auto_vacuum=, #cache_size, #cache_size=, #database_list, #default_cache_size, #default_cache_size=, #default_synchronous, #default_synchronous=, #default_temp_store, #default_temp_store=, #foreign_key_list, #full_column_names, #full_column_names=, #index_info, #index_list, #integrity_check, #parser_trace, #parser_trace=, #schema_cookie, #schema_cookie=, #synchronous, #synchronous=, #table_info, #temp_store, #temp_store=, #user_cookie, #user_cookie=, #vdbe_trace, #vdbe_trace=

Constructor Details

#initialize(uri, opts = {}) ⇒ Database

Returns a new instance of Database.



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# File 'lib/sqlite3/database.rb', line 94

def initialize(uri, opts = {})
  fail TypeError, "invalid uri" unless uri.is_a? String

  @results_as_hash = opts[:results_as_hash] || false
  @functions = {}
  @collations = {}
  @authorizer = nil
  @tracefunc = nil
  @encoding = nil
  @busy_handler = nil
  @db = Pointer.malloc(SIZEOF_VOIDP)

  if uri.encoding == Encoding::UTF_16LE ||
     uri.encoding == Encoding::UTF_16BE
    check Driver.sqlite3_open16(uri, @db.ref)
  else
    if opts[:readonly]
      mode = OPEN_READONLY
    else
      mode = OPEN_READWRITE | OPEN_CREATE;
    end
    uri = uri.encode(Encoding::UTF_8)
    check Driver.sqlite3_open_v2(uri, @db.ref, mode, nil)
  end

  if block_given?
    begin
      yield self
    ensure
      close
    end
  end
end

Instance Attribute Details

#collations ⇒ Object (readonly)

Returns the value of attribute collations.



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# File 'lib/sqlite3/database.rb', line 128

def collations
  @collations
end

#results_as_hash ⇒ Object

A boolean that indicates whether rows in result sets should be returned as hashes or not. By default, rows are returned as arrays.



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# File 'lib/sqlite3/database.rb', line 132

def results_as_hash
  @results_as_hash
end

Class Method Details

.quote(string) ⇒ Object

Quotes the given string, making it safe to use in an SQL statement. It replaces all instances of the single-quote character with two single-quote characters. The modified string is returned.



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# File 'lib/sqlite3/database.rb', line 88

def quote( string )
  string.gsub( /'/, "''" )
end

Instance Method Details

#authorizer(&block) ⇒ Object 



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# File 'lib/sqlite3/database.rb', line 224

def authorizer(&block)
  self.authorizer = block if block_given?
  @authorizer
end

#authorizer=(handler) ⇒ Object

call-seq: set_authorizer = auth

Set the authorizer for this database. auth must respond to call, and call must take 5 arguments.

Installs (or removes) a block that will be invoked for every access to the database. If the block returns 0 (or true), the statement is allowed to proceed. Returning 1 or false causes an authorization error to occur, and returning 2 or nil causes the access to be silently denied.



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# File 'lib/sqlite3/database.rb', line 197

def authorizer=(handler)
  must_be_open!
  @authorizer = handler

  if handler
    auth = Closure::BlockCaller.new(TYPE_VOIDP, AUTH_PARAMS) do |*args|
      args.shift # remove nil
      ruby_args = [args.shift]
      args.each do |ptr|
        ruby_args << ptr.null? ? nil : ptr.to_s
      end
      ret = @authorizer.call(*ruby_args)
      if ret.is_a? Fixnum
        ret
      elsif ret == false || ret == true
        ret == true ? OK : DENY
      else
        IGNORE
      end
    end
  else
    auth = nil
  end

  check Driver.sqlite3_set_authorizer(@db, auth, nil)
end

#busy_handler(handler = nil, &block) ⇒ Object 



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# File 'lib/sqlite3/database.rb', line 153

def busy_handler(handler = nil, &block)
  must_be_open!
  if handler.nil? and block_given?
    @busy_handler = block
  else
    @busy_handler = nil
  end

  cb = Closure::BlockCaller.new(TYPE_INT, BUSY_PARAMS) do |_, count|
    @busy_handler.call(self, count) ? 1 : 0
  end if @busy_handler

  check Driver.sqlite3_busy_handler(@db, cb, nil)
end

#busy_timeout(ms) ⇒ Object 



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# File 'lib/sqlite3/database.rb', line 229

def busy_timeout(ms)
  must_be_open!
  Driver.sqlite3_busy_timeout(@db, ms)
end

#changes ⇒ Object 



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# File 'lib/sqlite3/database.rb', line 586

def changes
  must_be_open!
  Driver.sqlite3_changes(@db)
end

#check(error_code) ⇒ Object 



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# File 'lib/sqlite3/database.rb', line 772

def check(error_code)
  if error_code != SQLITE_OK
    ptr = Driver.sqlite3_errmsg(@db)
    fail(ERR_EXEPTION_MAPPING[error_code] || RuntimeError, ptr.to_s)
  end
  error_code
end

#close ⇒ Object 



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# File 'lib/sqlite3/database.rb', line 134

def close
  must_be_open!
  check Driver.sqlite3_close(@db)
  @db = nil
end

#closed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/sqlite3/database.rb', line 140

def closed?
  @db.nil?
end

#collation(name, comparator) ⇒ Object

call-seq: db.collation(name, comparator)

Add a collation with name name, and a comparator object. The comparator object should implement a method called “compare” that takes two parameters and returns an integer less than, equal to, or greater than 0.



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# File 'lib/sqlite3/database.rb', line 174

def collation(name, comparator)
  must_be_open!
  cb = Closure::BlockCaller.new(TYPE_INT, COLLATION_PARAMS) do |_, aenc, astr, benc, bstr|
    target = Encoding.default_internal || Encoding::UTF_8
    comparator.compare(sqlite_encoding(astr.to_s, aenc).encode(target),
                       sqlite_encoding(bstr.to_s, benc).encode(target)).to_i
  end if comparator
  @collations[name] = comparator

  check Driver.sqlite3_create_collation(@db, name,
        Constants::TextRep::UTF8, nil, cb);
end

#commit ⇒ Object

Commits the current transaction. If there is no current transaction, this will cause an error to be raised. This returns true, in order to allow it to be used in idioms like abort? and rollback or commit.



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# File 'lib/sqlite3/database.rb', line 758

def commit
  execute "commit transaction"
  true
end

#complete?(sql) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/sqlite3/database.rb', line 582

def complete?(sql)
  Driver.sqlite3_complete(sql.to_s) == 1
end

#create_aggregate(name, arity, step = nil, finalize = nil, text_rep = Constants::TextRep::ANY, &block) ⇒ Object

Creates a new aggregate function for use in SQL statements. Aggregate functions are functions that apply over every row in the result set, instead of over just a single row. (A very common aggregate function is the “count” function, for determining the number of rows that match a query.)

The new function will be added as name, with the given arity. (For variable arity functions, use -1 for the arity.)

The step parameter must be a proc object that accepts as its first parameter a FunctionProxy instance (representing the function invocation), with any subsequent parameters (up to the function’s arity). The step callback will be invoked once for each row of the result set.

The finalize parameter must be a proc object that accepts only a single parameter, the FunctionProxy instance representing the current function invocation. It should invoke FunctionProxy#result= to store the result of the function.

Example:

db.create_aggregate( "lengths", 1 ) do
  step do |func, value|
    func[ :total ] ||= 0
    func[ :total ] += ( value ? value.length : 0 )
  end

  finalize do |func|
    func.result = func[ :total ] || 0
  end
end

puts db.get_first_value( "select lengths(name) from table" )

See also #create_aggregate_handler for a more object-oriented approach to aggregate functions.



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# File 'lib/sqlite3/database.rb', line 308

def create_aggregate( name, arity, step=nil, finalize=nil,
  text_rep=Constants::TextRep::ANY, &block )

  factory = Class.new do
    def self.step( &block )
      define_method(:step, &block)
    end

    def self.finalize( &block )
      define_method(:finalize, &block)
    end
  end

  if block_given?
    factory.instance_eval(&block)
  else
    factory.class_eval do
      define_method(:step, step)
      define_method(:finalize, finalize)
    end
  end

  proxy = factory.new
  proxy.extend(Module.new {
    attr_accessor :ctx

    def step( *args )
      super(@ctx, *args)
    end

    def finalize
      super(@ctx)
    end
  })
  proxy.ctx = FunctionProxy.new
  define_aggregator(name, proxy)
end

#create_aggregate_handler(handler) ⇒ Object

This is another approach to creating an aggregate function (see #create_aggregate). Instead of explicitly specifying the name, callbacks, arity, and type, you specify a factory object (the “handler”) that knows how to obtain all of that information. The handler should respond to the following messages:

arity

corresponds to the arity parameter of #create_aggregate. This message is optional, and if the handler does not respond to it, the function will have an arity of -1.

name

this is the name of the function. The handler must implement this message.

new

this must be implemented by the handler. It should return a new instance of the object that will handle a specific invocation of the function.

The handler instance (the object returned by the new message, described above), must respond to the following messages:

step

this is the method that will be called for each step of the aggregate function’s evaluation. It should implement the same signature as the step callback for #create_aggregate.

finalize

this is the method that will be called to finalize the aggregate function’s evaluation. It should implement the same signature as the finalize callback for #create_aggregate.

Example:

class LengthsAggregateHandler
  def self.arity; 1; end
  def self.name; 'lengths'; end

  def initialize
    @total = 0
  end

  def step( ctx, name )
    @total += ( name ? name.length : 0 )
  end

  def finalize( ctx )
    ctx.result = @total
  end
end

db.create_aggregate_handler( LengthsAggregateHandler )
puts db.get_first_value( "select lengths(name) from A" )



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# File 'lib/sqlite3/database.rb', line 393

def create_aggregate_handler( handler )
  proxy = Class.new do
    def initialize klass
      @klass = klass
      @fp    = FunctionProxy.new
    end

    def step( *args )
      instance.step(@fp, *args)
    end

    def finalize
      instance.finalize @fp
      @instance = nil
      @fp.result
    end

    private

    def instance
      @instance ||= @klass.new
    end
  end
  define_aggregator(handler.name, proxy.new(handler))
  self
end

#create_function(name, arity, text_rep = Constants::TextRep::ANY, &handler) ⇒ Object

Creates a new function for use in SQL statements. It will be added as name, with the given arity. (For variable arity functions, use -1 for the arity.)

The block should accept at least one parameter–the FunctionProxy instance that wraps this function invocation–and any other arguments it needs (up to its arity).

The block does not return a value directly. Instead, it will invoke the FunctionProxy#result= method on the func parameter and indicate the return value that way.

Example:

db.create_function( "maim", 1 ) do |func, value|
  if value.nil?
    func.result = nil
  else
    func.result = value.split(//).sort.join
  end
end

puts db.get_first_value( "select maim(name) from table" )



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# File 'lib/sqlite3/database.rb', line 443

def create_function(name, arity, text_rep=Constants::TextRep::ANY, &handler)
  must_be_open!
  @functions[name] = handler
  check Driver.sqlite3_create_function(@db, name, arity,
    text_rep, nil, compile_function(FunctionProxy.proxy(handler)), nil, nil)
end

#define_aggregator(name, aggregator) ⇒ Object

call-seq: define_aggregator(name, aggregator)

Define an aggregate function named name using the object aggregator. aggregator must respond to step and finalize. step will be called with row information and finalize must return the return value for the aggregator function.



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# File 'lib/sqlite3/database.rb', line 253

def define_aggregator(name, aggregator)
  must_be_open!
  @functions[name] = aggregator

  step = Closure::BlockCaller.new(TYPE_VOIDP, FUNC_PARAMS) do |_, argc, argv|
    aggregator.step(*native_to_ruby_args(argc, argv))
    0 # return something
  end

  fin = Closure::BlockCaller.new(TYPE_VOIDP, FUNC_PARAMS) do |ctx, _, _|
    Driver.set_context_result(ctx, aggregator.finalize())
    0 # return something
  end

check Driver.sqlite3_create_function(@db, name,
    aggregator.method(:step).arity,
    Constants::TextRep::UTF8, nil, nil, step, fin)
end

#define_function(name, &handler) ⇒ Object

call-seq: define_function(name) { |args,…| }

Define a function named name with args. The arity of the block will be used as the arity for the function defined.



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# File 'lib/sqlite3/database.rb', line 239

def define_function(name, &handler)
  must_be_open!
  @functions[name] = handler
  check Driver.sqlite3_create_function(@db, name, handler.arity,
    Constants::TextRep::UTF8, nil, compile_function(handler), nil, nil)
end

#encoding ⇒ Object 



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# File 'lib/sqlite3/database.rb', line 720

def encoding
  @encoding = Encoding.find(get_first_value('PRAGMA encoding'))
end

#errcode ⇒ Object 



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# File 'lib/sqlite3/database.rb', line 591

def errcode
  must_be_open!
  Driver.sqlite3_errcode(@db)
end

#errmsg ⇒ Object 



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# File 'lib/sqlite3/database.rb', line 596

def errmsg
  must_be_open!
  Driver.sqlite3_errmsg(@db).to_s
end

#execute(sql, bind_vars = [], *args, &block) ⇒ Object Also known as: exec

Executes the given SQL statement. If additional parameters are given, they are treated as bind variables, and are bound to the placeholders in the query.

Note that if any of the values passed to this are hashes, then the key/value pairs are each bound separately, with the key being used as the name of the placeholder to bind the value to.

The block is optional. If given, it will be invoked for each row returned by the query. Otherwise, any results are accumulated into an array and returned wholesale.

See also #execute2, #query, and #execute_batch for additional ways of executing statements.



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# File 'lib/sqlite3/database.rb', line 486

def execute sql, bind_vars = [], *args, &block
  if bind_vars.nil? || !args.empty?
    if args.empty?
      bind_vars = []
    else
      bind_vars = [bind_vars] + args
    end
  end

  prepare( sql ) do |stmt|
    stmt.bind_params(bind_vars)
    columns = stmt.columns

    if block_given?
      stmt.each do |row|
        if @results_as_hash
          yield ordered_map_for(columns, row)
        else
          yield row
        end
      end
    else
      if @results_as_hash
        stmt.map { |row| ordered_map_for(columns, row) }
      else
        stmt.to_a
      end
    end
  end
end

#execute2(sql, *bind_vars) ⇒ Object

Executes the given SQL statement, exactly as with #execute. However, the first row returned (either via the block, or in the returned array) is always the names of the columns. Subsequent rows correspond to the data from the result set.

Thus, even if the query itself returns no rows, this method will always return at least one row–the names of the columns.

See also #execute, #query, and #execute_batch for additional ways of executing statements.



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# File 'lib/sqlite3/database.rb', line 527

def execute2( sql, *bind_vars )
  prepare( sql ) do |stmt|
    result = stmt.execute( *bind_vars )
    if block_given?
      yield stmt.columns
      result.each { |row| yield row }
    else
      return result.inject( [ stmt.columns ] ) { |arr,row|
        arr << row; arr }
    end
  end
end

#execute_batch(sql, bind_vars = [], *args) ⇒ Object Also known as: batch

Executes all SQL statements in the given string. By contrast, the other means of executing queries will only execute the first statement in the string, ignoring all subsequent statements. This will execute each one in turn. The same bind parameters, if given, will be applied to each statement.

This always returns nil, making it unsuitable for queries that return rows.



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# File 'lib/sqlite3/database.rb', line 548

def execute_batch( sql, bind_vars = [], *args )
  # FIXME: remove this stuff later
  unless [Array, Hash].include?(bind_vars.class)
    bind_vars = [bind_vars]
  end

  # FIXME: remove this stuff later
  if bind_vars.nil? || !args.empty?
    if args.empty?
      bind_vars = []
    else
      bind_vars = [nil] + args
    end
  end
  sql = sql.strip
  until sql.empty? do
    prepare( sql ) do |stmt|
      unless stmt.closed?
        # FIXME: this should probably use sqlite3's api for batch execution
        # This implementation requires stepping over the results.
        if bind_vars.length == stmt.bind_parameter_count
          stmt.bind_params(bind_vars)
        end
        stmt.step
      end
      sql = stmt.remainder.strip
    end
  end
  # FIXME: we should not return `nil` as a success return value
  nil
end

#get_first_row(sql, *bind_vars) ⇒ Object

A convenience method for obtaining the first row of a result set, and discarding all others. It is otherwise identical to #execute.

See also #get_first_value.



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# File 'lib/sqlite3/database.rb', line 667

def get_first_row( sql, *bind_vars )
  execute( sql, *bind_vars ).first
end

#get_first_value(sql, *bind_vars) ⇒ Object

A convenience method for obtaining the first value of the first row of a result set, and discarding all other values and rows. It is otherwise identical to #execute.

See also #get_first_row.



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# File 'lib/sqlite3/database.rb', line 676

def get_first_value( sql, *bind_vars )
  execute( sql, *bind_vars ) { |row| return row[0] }
  nil
end

#handle ⇒ Object 



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# File 'lib/sqlite3/database.rb', line 144

def handle
  @db
end

#interrupt ⇒ Object 



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# File 'lib/sqlite3/database.rb', line 148

def interrupt
  must_be_open!
  Driver.sqlite3_interrupt(@db)
end

#last_insert_row_id ⇒ Object 



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# File 'lib/sqlite3/database.rb', line 606

def last_insert_row_id
  must_be_open!
  Driver.sqlite3_last_insert_rowid(@db)
end

#prepare(sql) ⇒ Object

Returns a Statement object representing the given SQL. This does not execute the statement; it merely prepares the statement for execution.

The Statement can then be executed using Statement#execute.



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# File 'lib/sqlite3/database.rb', line 651

def prepare sql
  must_be_open!
  stmt = SQLite3::Statement.new(self, sql)
  return stmt unless block_given?

  begin
    yield stmt
  ensure
    stmt.close unless stmt.closed?
  end
end

#query(sql, bind_vars = [], *args) ⇒ Object

This is a convenience method for creating a statement, binding paramters to it, and calling execute:

result = db.query( "select * from foo where a=?", [5])
# is the same as
result = db.prepare( "select * from foo where a=?" ).execute( 5 )

You must be sure to call close on the ResultSet instance that is returned, or you could have problems with locks on the table. If called with a block, close will be invoked implicitly when the block terminates.



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# File 'lib/sqlite3/database.rb', line 622

def query( sql, bind_vars = [], *args )

  if bind_vars.nil? || !args.empty?
    if args.empty?
      bind_vars = []
    else
      bind_vars = [bind_vars] + args
    end
  end

  result = prepare( sql ).execute( bind_vars )
  if block_given?
    begin
      yield result
    ensure
      result.close
    end
  else
    return result
  end
end

#readonly?(db = 'main') ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/sqlite3/database.rb', line 749

def readonly?(db = 'main')
  must_be_open!
  Driver.sqlite3_db_readonly(@db, db.to_s) == 1
end

#rollback ⇒ Object

Rolls the current transaction back. If there is no current transaction, this will cause an error to be raised. This returns true, in order to allow it to be used in idioms like abort? and rollback or commit.



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# File 'lib/sqlite3/database.rb', line 767

def rollback
  execute "rollback transaction"
  true
end

#total_changes ⇒ Object 



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# File 'lib/sqlite3/database.rb', line 601

def total_changes
  must_be_open!
  Driver.sqlite3_total_changes(@db)
end

#trace(tracer = nil, &block) ⇒ Object

call-seq:

trace { |sql| ... }
trace(Class.new { def call sql; end }.new)

Installs (or removes) a block that will be invoked for every SQL statement executed. The block receives one parameter: the SQL statement executed. If the block is nil, any existing tracer will be uninstalled.



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# File 'lib/sqlite3/database.rb', line 732

def trace(tracer = nil, &block)
  must_be_open!

  tracer = block if block_given?
  @tracefunc = tracer

  if tracer
    cb = Closure::BlockCaller.new(TYPE_VOIDP, TRACE_PARAMS) do |_, sql|
      tracer.call(sql.to_s)
      0 # return something
    end
  end

  Driver.sqlite3_trace(@db, cb, nil)
  @tracefunc
end

#transaction(mode = :deferred) ⇒ Object

Begins a new transaction. Note that nested transactions are not allowed by SQLite, so attempting to nest a transaction will result in a runtime exception.

The mode parameter may be either :deferred (the default), :immediate, or :exclusive.

If a block is given, the database instance is yielded to it, and the transaction is committed when the block terminates. If the block raises an exception, a rollback will be performed instead. Note that if a block is given, #commit and #rollback should never be called explicitly or you’ll get an error when the block terminates.

If a block is not given, it is the caller’s responsibility to end the transaction explicitly, either by calling #commit, or by calling #rollback.



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# File 'lib/sqlite3/database.rb', line 697

def transaction( mode = :deferred )
  execute "begin #{mode.to_s} transaction"

  if block_given?
    abort = false
    begin
      yield self
    rescue ::Object
      abort = true
      raise
    ensure
      abort and rollback or commit
    end
  end

  true
end

#transaction_active? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/sqlite3/database.rb', line 715

def transaction_active?
  must_be_open!
  Driver.sqlite3_get_autocommit(@db) != 1
end