Mysql2::Error: Incorrect string value

Question

I have a rails application running on production mode, but all of the sudden this error came up today when a user tried to save a record.

Answer 1

I managed to store emojis (which take up 4 bytes) by following this blog post:

Rails 4, MySQL, and Emoji (Mysql2::Error: Incorrect string value error.)

You might think that you’re safe inserting most utf8 data in to mysql when you’ve specified that the charset is utf-8. Sadly, however, you’d be wrong. The problem is that the utf8 character set takes up 3 bytes when stored in a VARCHAR column. Emoji characters, on the other hand, take up 4 bytes.

The solution is in 2 parts:

Change the encoding of your table and fields:

ALTER TABLE `[table]` 
  CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_bin,
MODIFY [column] VARCHAR(250)
    CHARACTER SET utf8mb4 COLLATE utf8mb4_bin

Tell the mysql2 adapter about it:

development:
  adapter: mysql2
  database: db
  username: 
  password:
  encoding: utf8mb4
  collation: utf8mb4_unicode_ci

Hope this helps someone!

Then I had to restart my app and it worked. Please note that some emojis will work without this fix, while some won't:

• ➡️ Did work