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
306 def initialize(h=OPTS)
307   @columns = h[:columns]
308   @column_converters = h[:column_converters]
309   @column_oids = h[:column_oids]
310   @converter = h[:converter]
311   @typecaster = h[:typecaster]
312   @oid = h[:oid]
313 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
317 def call(s)
318   convert(convert_format(convert_columns(Splitter.new(s).parse)))
319 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
325 def typecast(obj)
326   case obj 
327   when Array
328     _typecast(convert_format(obj))
329   when Hash
330     unless @columns
331       raise Error, 'PGRow::Parser without columns cannot typecast from a hash'
332     end
333     _typecast(obj)
334   else
335     raise Error, 'PGRow::Parser can only typecast arrays and hashes'
336   end
337 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
343 def _typecast(obj)
344   if t = @typecaster
345     t.call(obj)
346   else
347     obj
348   end
349 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
376 def convert(obj)
377   if c = @converter
378     c.call(obj)
379   else
380     obj
381   end
382 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
354 def convert_columns(arr)
355   if ccs = @column_converters
356     arr.zip(ccs).map{|v, pr| (v && pr) ? pr.call(v) : v}
357   else
358     arr 
359   end
360 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
364 def convert_format(arr)
365   if cs = @columns
366     h = {}
367     arr.zip(cs).each{|v, c| h[c] = v}
368     h
369   else
370     arr
371   end
372 end