Read PostgreSQL Bytea column in Ruby

Question

I am trying to read a bytea column from PostgreSQL using Ruby. The problem is that it returns the hex encoded string of the bytea value. I would like it to return exactly the same as if I would open a binary file with the same content with File.read().

The following gives me the hex encoded value:

require 'pg'

conn = PG.connect(...)
res  = conn.exec('SELECT bytea_column FROM some_table')
res.each do |r|
    raw = r['bytea_column']
    puts "#{raw}"
end

I think I need to use PG::TextDecoder::Bytea to decode the bytea column correctly. Is this correct? And if so, how exactly is it supposed to be used?

max · Accepted Answer · 2017-06-26 15:31:46Z

5

Thanks everyone but I figured it out. The answer is PG::Connection.unescape_bytea:

require 'pg'

conn = PG.connect(...)
res  = conn.exec('SELECT bytea_column FROM some_table')  
res.each do |r|
    raw = r['bytea_column']
    binary_data = PG::Connection.unescape_bytea(raw)
    puts "#{binary_data}"
end

answered Jun 26, 2017 at 15:31

max

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1 Comment

tadman Over a year ago

One thing to avoid in Ruby is doing "#{x}" instead of x. There's no reason to surround something in quotes like that. puts will convert to a string if it feels it's necessary.

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