Retrieving MySQL BLOB field with Ruby/Rails

Question

I make this simple MySQL query using ActiveRecord::Base

sql = "SELECT * FROM schedules WHERE id = 1"
schedule = (ActiveRecord::Base.connection.select_rows sql)[0]

It happens that schedule[9] is BLOB data, but it gets retrieved as a ruby String object. Is that normal? How are BLOB objects represented in ruby? Coming from the Objective-C world, BLOB data is usually represented by NSData objects. Is there some kind of equivalent in Ruby?

If you can, use p schedule and visually inspect the array. An array of bytes, perhaps? — thisfeller
– thisfeller, Commented Jul 6, 2012 at 21:05

Frederick Cheung · Accepted Answer · 2012-07-06 21:18:32Z

1

Strings in ruby are just a sequence of arbitrary bytes - there is no separate data type.

Strings can be given an encoding which tells ruby to interpret the bytes as utf-8, utf-16, ISO-latin etc. when doing various operations on them but there's also the ASCII-8bit encoding (bit of a misnomer) which just means arbitrary bytes.

answered Jul 6, 2012 at 21:18

Frederick Cheung

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James Daniels · Accepted Answer · 2012-07-06 21:02:53Z

0

If it isn't a serialized record in your model than a Blob is nothing other than a string which doesn't have size constraints. Strings are the base "data" object in Ruby.

answered Jul 6, 2012 at 21:02

James Daniels

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