How do you access the bit mysql data type in ruby on rails 2?

Question

I have a field of type bit in a MySQL database, but I'm not sure how to access the value.

The ruby debug method gives me (note the spaces, they are probably invisible characters stored in binary form):

--- &id001 !ruby/object:Room 
attributes: 
  bit_field_false: !binary |
    AA==

  bit_field_true: !binary |
    AQ==

bit_field_false and bit_field_true should be false and true respectively. I've also noticed some weird properties:

When I convert them to integers, they both show as 0
When I extract truth values, ie, <%= @room.bit_field_true ? "true" : "false" %> and <%= @room.bit_field_false ? "true" : "false" %>, they both yield true
When I show them as strings they show as empty strings

How to I get their respective values? Do the binary values mean anything?

The end goal is to show them in a checkbox, and I have something like:

<% form_for(@room) do |room_f| %>
  <%= check_box_tag :room_bit_field_false %><br/>
  <%= check_box_tag :room_bit_field_true %><br/>
<% end %>

but it always shows as unchecked. I'm not certain this is how to create checkboxes for this set up, so this could be wrong as well, but regardless I want to know how to extract the bit values in code.

For reference, I'm using Ruby on Rails 2.3.2, with the mysql adapter and mysql Ver 14.14 Distrib 5.5.10, for osx10.6 (i386).

Community · Accepted Answer · 2017-05-23 12:16:44Z

2

I discovered something a lot simpler than bitfields as suggested by https://stackoverflow.com/a/11394467/111884 (which I couldn't get working - maybe it was rails 2 or something) - the method getbyte.

You can get the first bit with:

bit_field_false.getbyte(0)  # Returns `0`
bit_field_true.getbyte(0)   # Returns `1`

Also found that you can do this:

bit_field_false == "\0"  # Returns `true`
bit_field_false == "\1"  # Returns `false`

bit_field_true == "\0"   # Returns `false`
bit_field_true == "\1"   # Returns `true`

edited May 23, 2017 at 12:16

CommunityBot

11 silver badge

answered Jul 9, 2012 at 14:30

zlog

3,3165 gold badges44 silver badges83 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

mylescarrick · Accepted Answer · 2012-07-09 11:51:46Z

0

If you're just using the bit field to store boolean values I'd suggest you're making your life a lot harder than it needs to be.

Use boolean fields here and it'll all be far simpler. Working hard like this is usually an indicator that you're working against Rails, not with it.

... having said that, I've worked with bit fields and Redis a bit (for storing permissions). If you want to do it in ActiveRecord, a plugin like https://github.com/grosser/bitfields seems like a much nicer way to do it.

answered Jul 9, 2012 at 11:51

mylescarrick

1,6808 silver badges10 bronze badges

2 Comments

zlog Over a year ago

I'm working with an existing database, and the rails site is more of a wrapper around the data, which is generated elsewhere. So it would be easier to get the bit datatype working, than modify the database. Thanks for the tip on bitfields plugin - I'll give it a go.

GoinAum Over a year ago

When you said 'boolean' in the 2nd paragraph, I think you meant an alternative, such as an integer. If I remember correctly, unless you're piling up bitfields into larger quantities (some quantity of 8, because of how they get stored) you don't really get any space savings. Unless you have a serious space constraint, the native integer speed, plus the ease of dealing with Rails, would make an alternative a better choice.

Collectives™ on Stack Overflow

How do you access the bit mysql data type in ruby on rails 2?

2 Answers 2

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related