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
304 def initialize(h=OPTS)
305   @columns = h[:columns]
306   @column_converters = h[:column_converters]
307   @column_oids = h[:column_oids]
308   @converter = h[:converter]
309   @typecaster = h[:typecaster]
310   @oid = h[:oid]
311 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
315 def call(s)
316   convert(convert_format(convert_columns(Splitter.new(s).parse)))
317 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
323 def typecast(obj)
324   case obj 
325   when Array
326     _typecast(convert_format(obj))
327   when Hash
328     unless @columns
329       raise Error, 'PGRow::Parser without columns cannot typecast from a hash'
330     end
331     _typecast(obj)
332   else
333     raise Error, 'PGRow::Parser can only typecast arrays and hashes'
334   end
335 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
341 def _typecast(obj)
342   if t = @typecaster
343     t.call(obj)
344   else
345     obj
346   end
347 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
374 def convert(obj)
375   if c = @converter
376     c.call(obj)
377   else
378     obj
379   end
380 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
352 def convert_columns(arr)
353   if ccs = @column_converters
354     arr.zip(ccs).map{|v, pr| (v && pr) ? pr.call(v) : v}
355   else
356     arr 
357   end
358 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
362 def convert_format(arr)
363   if cs = @columns
364     h = {}
365     arr.zip(cs).each{|v, c| h[c] = v}
366     h
367   else
368     arr
369   end
370 end