class Sequel::Postgres::PGRow::Parser

The Parser is responsible for taking the input string from PostgreSQL, and returning an appropriate ruby object that the type represents, such as an ArrayRow or HashRow.

Attributes

column_converters[R]

Converters for each member in the composite type. If not present, no conversion will be done, so values will remain strings. If present, should be an array of callable objects.

column_oids[R]

The OIDs for each member in the composite type. Not currently used, but made available for user code.

columns[R]

The columns for the parser, if any. If the parser has no columns, it will treat the input as an array. If it has columns, it will treat the input as a hash. If present, should be an array of strings.

converter[R]

A converter for the object as a whole. Used to wrap the returned array/hash in another object, such as an ArrayRow or HashRow. If present, should be callable.

oid[R]

The oid for the composite type itself.

typecaster[R]

A callable object used for typecasting the object. This is similar to the converter, but it is called by the typecasting code, which has different assumptions than the converter. For instance, the converter should be called with all of the member values already typecast, but the typecaster may not be.

Public Class Methods

new(h=OPTS) click to toggle source

Sets each of the parser's attributes, using options with the same name (e.g. :columns sets the columns attribute).

# File lib/sequel/extensions/pg_row.rb, line 296
def initialize(h=OPTS)
  @columns = h[:columns]
  @column_converters = h[:column_converters]
  @column_oids = h[:column_oids]
  @converter = h[:converter]
  @typecaster = h[:typecaster]
  @oid = h[:oid]
end

Public Instance Methods

call(s) click to toggle source

Convert the PostgreSQL composite type input format into an appropriate ruby object.

# File lib/sequel/extensions/pg_row.rb, line 307
def call(s)
  convert(convert_format(convert_columns(Splitter.new(s).parse)))
end
typecast(obj) click to toggle source

Typecast the given object to the appropriate type using the typecaster. Note that this does not conversion for the members of the composite type, since those conversion expect strings and strings may not be provided.

# File lib/sequel/extensions/pg_row.rb, line 315
def typecast(obj)
  case obj 
  when Array
    _typecast(convert_format(obj))
  when Hash
    unless @columns
      raise Error, 'PGRow::Parser without columns cannot typecast from a hash'
    end
    _typecast(obj)
  else
    raise Error, 'PGRow::Parser can only typecast arrays and hashes'
  end
end

Private Instance Methods

_typecast(obj) click to toggle source

If the parser has a typecaster, call it with the object, otherwise return the object as is.

# File lib/sequel/extensions/pg_row.rb, line 333
def _typecast(obj)
  if t = @typecaster
    t.call(obj)
  else
    obj
  end
end
convert(obj) click to toggle source

If the parser has a converter, call it with the object, otherwise return the object as is.

# File lib/sequel/extensions/pg_row.rb, line 366
def convert(obj)
  if c = @converter
    c.call(obj)
  else
    obj
  end
end
convert_columns(arr) click to toggle source

If the parser has column converters, map the array of strings input to a array of appropriate ruby objects, one for each converter.

# File lib/sequel/extensions/pg_row.rb, line 344
def convert_columns(arr)
  if ccs = @column_converters
    arr.zip(ccs).map{|v, pr| (v && pr) ? pr.call(v) : v}
  else
    arr 
  end
end
convert_format(arr) click to toggle source

If the parser has columns, return a hash assuming that the array is ordered by the columns.

# File lib/sequel/extensions/pg_row.rb, line 354
def convert_format(arr)
  if cs = @columns
    h = {}
    arr.zip(cs).each{|v, c| h[c] = v}
    h
  else
    arr
  end
end