Module: Sequel::Litedb::DatasetMethods

Includes:
Dataset::Replace, UnmodifiedIdentifiers::DatasetMethods
Defined in:
lib/sequel/adapters/shared/litedb.rb

Constant Summary collapse

INSERT_CONFLICT_RESOLUTIONS =

The allowed values for insert_conflict

%w[ROLLBACK ABORT FAIL IGNORE REPLACE].each(&:freeze).freeze
CONSTANT_MAP = 
{CURRENT_DATE: "date(CURRENT_TIMESTAMP, 'localtime')", CURRENT_TIMESTAMP: "datetime(CURRENT_TIMESTAMP, 'localtime')", CURRENT_TIME: "time(CURRENT_TIMESTAMP, 'localtime')"}.freeze
EXTRACT_MAP = 
{year: "'%Y'", month: "'%m'", day: "'%d'", hour: "'%H'", minute: "'%M'", second: "'%f'"}.freeze

Instance Method Summary collapse

Instance Method Details

#cast_sql_append(sql, expr, type) ⇒ Object 



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# File 'lib/sequel/adapters/shared/litedb.rb', line 584

def cast_sql_append(sql, expr, type)
  if type == Time || type == DateTime
    sql << "datetime("
    literal_append(sql, expr)
    sql << ")"
  elsif type == Date
    sql << "date("
    literal_append(sql, expr)
    sql << ")"
  else
    super
  end
end

#complex_expression_sql_append(sql, op, args) ⇒ Object

SQLite doesn’t support a NOT LIKE b, you need to use NOT (a LIKE b). It doesn’t support xor, power, or the extract function natively, so those have to be emulated.



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# File 'lib/sequel/adapters/shared/litedb.rb', line 600

def complex_expression_sql_append(sql, op, args)
  case op
  when :"NOT LIKE", :"NOT ILIKE"
    sql << "NOT "
    complex_expression_sql_append(sql, ((op == :"NOT ILIKE") ? :ILIKE : :LIKE), args)
  when :^
    complex_expression_arg_pairs_append(sql, args) { |a, b| Sequel.lit(["((~(", " & ", ")) & (", " | ", "))"], a, b, a, b) }
  when :**
    unless (exp = args[1]).is_a?(Integer)
      raise(Sequel::Error, "can only emulate exponentiation on SQLite if exponent is an integer, given #{exp.inspect}")
    end
    case exp
    when 0
      sql << "1"
    else
      sql << "("
      arg = args[0]
      if exp < 0
        invert = true
        exp = exp.abs
        sql << "(1.0 / ("
      end
      (exp - 1).times do
        literal_append(sql, arg)
        sql << " * "
      end
      literal_append(sql, arg)
      sql << ")"
      if invert
        sql << "))"
      end
    end
  when :extract
    part = args[0]
    raise(Sequel::Error, "unsupported extract argument: #{part.inspect}") unless (format = EXTRACT_MAP[part])
    sql << "CAST(strftime(" << format << ", "
    literal_append(sql, args[1])
    sql << ") AS " << ((part == :second) ? "NUMERIC" : "INTEGER") << ")"
  else
    super
  end
end

#constant_sql_append(sql, constant) ⇒ Object

SQLite has CURRENT_TIMESTAMP and related constants in UTC instead of in localtime, so convert those constants to local time.



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# File 'lib/sequel/adapters/shared/litedb.rb', line 645

def constant_sql_append(sql, constant)
  if (c = CONSTANT_MAP[constant]) && !db.current_timestamp_utc
    sql << c
  else
    super
  end
end

#delete(&block) ⇒ Object

SQLite performs a TRUNCATE style DELETE if no filter is specified. Since we want to always return the count of records, add a condition that is always true and then delete.



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# File 'lib/sequel/adapters/shared/litedb.rb', line 656

def delete(&block)
  @opts[:where] ? super : where(1 => 1).delete(&block)
end

#empty? ⇒ Boolean

Always return false when using VALUES

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 661

def empty?
  return false if @opts[:values]
  super
end

#explain(opts = nil) ⇒ Object

Return an array of strings specifying a query explanation for a SELECT of the current dataset. Currently, the options are ignored, but it accepts options to be compatible with other adapters.



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# File 'lib/sequel/adapters/shared/litedb.rb', line 669

def explain(opts = nil)
  # Load the PrettyTable class, needed for explain output
  Sequel.extension(:_pretty_table) unless defined?(Sequel::PrettyTable)

  ds = db.send(:metadata_dataset).clone(sql: "EXPLAIN #{select_sql}")
  rows = ds.all
  Sequel::PrettyTable.string(rows, ds.columns)
end

#having(*cond) ⇒ Object

HAVING requires GROUP BY on SQLite

Raises:

  • (InvalidOperation) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 679

def having(*cond)
  raise(InvalidOperation, "Can only specify a HAVING clause on a grouped dataset") if !@opts[:group] && db.sqlite_version < 33900
  super
end

#insert_conflict(opts = :ignore) ⇒ Object

Handle uniqueness violations when inserting, by using a specified resolution algorithm. With no options, uses INSERT OR REPLACE. SQLite supports the following conflict resolution algorithms: ROLLBACK, ABORT, FAIL, IGNORE and REPLACE.

On SQLite 3.24.0+, you can pass a hash to use an ON CONFLICT clause. With out :update option, uses ON CONFLICT DO NOTHING. Options:

:conflict_where

The index filter, when using a partial index to determine uniqueness.

:target

The column name or expression to handle uniqueness violations on.

:update

A hash of columns and values to set. Uses ON CONFLICT DO UPDATE.

:update_where

A WHERE condition to use for the update.

Examples:

DB[:table].insert_conflict.insert(a: 1, b: 2)
# INSERT OR IGNORE INTO TABLE (a, b) VALUES (1, 2)

DB[:table].insert_conflict(:replace).insert(a: 1, b: 2)
# INSERT OR REPLACE INTO TABLE (a, b) VALUES (1, 2)

DB[:table].insert_conflict({}).insert(a: 1, b: 2)
# INSERT INTO TABLE (a, b) VALUES (1, 2)
# ON CONFLICT DO NOTHING

DB[:table].insert_conflict(target: :a).insert(a: 1, b: 2)
# INSERT INTO TABLE (a, b) VALUES (1, 2)
# ON CONFLICT (a) DO NOTHING

DB[:table].insert_conflict(target: :a, conflict_where: {c: true}).insert(a: 1, b: 2)
# INSERT INTO TABLE (a, b) VALUES (1, 2)
# ON CONFLICT (a) WHERE (c IS TRUE) DO NOTHING

DB[:table].insert_conflict(target: :a, update: {b: Sequel[:excluded][:b]}).insert(a: 1, b: 2)
# INSERT INTO TABLE (a, b) VALUES (1, 2)
# ON CONFLICT (a) DO UPDATE SET b = excluded.b

DB[:table].insert_conflict(target: :a,
  update: {b: Sequel[:excluded][:b]}, update_where: {Sequel[:table][:status_id] => 1}).insert(a: 1, b: 2)
# INSERT INTO TABLE (a, b) VALUES (1, 2)
# ON CONFLICT (a) DO UPDATE SET b = excluded.b WHERE (table.status_id = 1)



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# File 'lib/sequel/adapters/shared/litedb.rb', line 757

def insert_conflict(opts = :ignore)
  case opts
  when Symbol, String
    unless INSERT_CONFLICT_RESOLUTIONS.include?(opts.to_s.upcase)
      raise Error, "Invalid symbol or string passed to Dataset#insert_conflict: #{opts.inspect}.  The allowed values are: :rollback, :abort, :fail, :ignore, or :replace"
    end
    clone(insert_conflict: opts)
  when Hash
    clone(insert_on_conflict: opts)
  else
    raise Error, "Invalid value passed to Dataset#insert_conflict: #{opts.inspect}, should use a symbol or a hash"
  end
end

#insert_ignore ⇒ Object

Ignore uniqueness/exclusion violations when inserting, using INSERT OR IGNORE. Exists mostly for compatibility to MySQL’s insert_ignore. Example:

DB[:table].insert_ignore.insert(a: 1, b: 2)
# INSERT OR IGNORE INTO TABLE (a, b) VALUES (1, 2)



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# File 'lib/sequel/adapters/shared/litedb.rb', line 776

def insert_ignore
  insert_conflict(:ignore)
end

#insert_select(*values) ⇒ Object

Support insert select for associations, so that the model code can use returning instead of a separate query.



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# File 'lib/sequel/adapters/shared/litedb.rb', line 686

def insert_select(*values)
  return unless supports_insert_select?
  # Handle case where query does not return a row
  server?(:default).with_sql_first(insert_select_sql(*values)) || false
end

#insert_select_sql(*values) ⇒ Object

The SQL to use for an insert_select, adds a RETURNING clause to the insert unless the RETURNING clause is already present.



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# File 'lib/sequel/adapters/shared/litedb.rb', line 694

def insert_select_sql(*values)
  ds = opts[:returning] ? self : returning
  ds.insert_sql(*values)
end

#quoted_identifier_append(sql, c) ⇒ Object

SQLite uses the nonstandard ‘ (backtick) for quoting identifiers.



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# File 'lib/sequel/adapters/shared/litedb.rb', line 700

def quoted_identifier_append(sql, c)
  sql << "`" << c.to_s.gsub("`", "``") << "`"
end

#returning(*values) ⇒ Object

Automatically add aliases to RETURNING values to work around SQLite bug.

Raises:

  • (Error) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 781

def returning(*values)
  return super if values.empty?
  raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert)
  clone(returning: _returning_values(values).freeze)
end

#select(*cols) ⇒ Object

When a qualified column is selected on SQLite and the qualifier is a subselect, the column name used is the full qualified name (including the qualifier) instead of just the column name. To get correct column names, you must use an alias.



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# File 'lib/sequel/adapters/shared/litedb.rb', line 708

def select(*cols)
  if ((f = @opts[:from]) && f.any? { |t| t.is_a?(Dataset) || (t.is_a?(SQL::AliasedExpression) && t.expression.is_a?(Dataset)) }) || ((j = @opts[:join]) && j.any? { |t| t.table.is_a?(Dataset) })
    super(*cols.map { |c| alias_qualified_column(c) })
  else
    super
  end
end

#supports_cte?(type = :select) ⇒ Boolean

SQLite 3.8.3+ supports common table expressions.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 788

def supports_cte?(type = :select)
  db.sqlite_version >= 30803
end

#supports_cte_in_subqueries? ⇒ Boolean

SQLite supports CTEs in subqueries if it supports CTEs.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 793

def supports_cte_in_subqueries?
  supports_cte?
end

#supports_deleting_joins? ⇒ Boolean

SQLite does not support deleting from a joined dataset

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 803

def supports_deleting_joins?
  false
end

#supports_derived_column_lists? ⇒ Boolean

SQLite does not support table aliases with column aliases

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 798

def supports_derived_column_lists?
  false
end

#supports_intersect_except_all? ⇒ Boolean

SQLite does not support INTERSECT ALL or EXCEPT ALL

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 808

def supports_intersect_except_all?
  false
end

#supports_is_true? ⇒ Boolean

SQLite does not support IS TRUE

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 813

def supports_is_true?
  false
end

#supports_modifying_joins? ⇒ Boolean

SQLite 3.33.0 supports modifying joined datasets

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 818

def supports_modifying_joins?
  db.sqlite_version >= 33300
end

#supports_multiple_column_in? ⇒ Boolean

SQLite does not support multiple columns for the IN/NOT IN operators

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 823

def supports_multiple_column_in?
  false
end

#supports_returning?(_) ⇒ Boolean

SQLite 3.35.0 supports RETURNING on INSERT/UPDATE/DELETE.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 828

def supports_returning?(_)
  db.sqlite_version >= 33500
end

#supports_timestamp_timezones? ⇒ Boolean

SQLite supports timezones in literal timestamps, since it stores them as text. But using timezones in timestamps breaks SQLite datetime functions, so we allow the user to override the default per database.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 835

def supports_timestamp_timezones?
  db.use_timestamp_timezones?
end

#supports_where_true? ⇒ Boolean

SQLite cannot use WHERE ‘t’.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 840

def supports_where_true?
  false
end

#supports_window_clause? ⇒ Boolean

SQLite 3.28+ supports the WINDOW clause.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 845

def supports_window_clause?
  db.sqlite_version >= 32800
end

#supports_window_function_frame_option?(option) ⇒ Boolean

SQLite 3.28.0+ supports all window frame options that Sequel supports

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 858

def supports_window_function_frame_option?(option)
  (db.sqlite_version >= 32800) ? true : super
end

#supports_window_functions? ⇒ Boolean

SQLite 3.25+ supports window functions. However, support is only enabled on SQLite 3.26.0+ because internal Sequel usage of window functions to implement eager loading of limited associations triggers an SQLite crash bug in versions 3.25.0-3.25.3.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/litedb.rb', line 853

def supports_window_functions?
  db.sqlite_version >= 32600
end