Difference between string and text in rails?

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I'm making a new web app using Rails, and was wondering, what's the difference between string and text? And when should each be used?

9 Answers

The accepted answer is awesome, it properly explains the difference between string vs text (mostly the limit size in the database, but there are a few other gotchas), but I wanted to point out a small issue that got me through it as that answer didn't completely do it for me.

The max size :limit => 1 to 4294967296 didn't work exactly as put, I needed to go -1 from that max size. I'm storing large JSON blobs and they might be crazy huge sometimes.

Here's my migration with the larger value in place with the value MySQL doesn't complain about.

Note the 5 at the end of the limit instead of 6

class ChangeUserSyncRecordDetailsToText < ActiveRecord::Migration[5.1]
  def up
    change_column :user_sync_records, :details, :text, :limit => 4294967295
  end

  def down
    change_column :user_sync_records, :details, :string, :limit => 1000
  end
end

If you are using oracle... STRING will be created as VARCHAR(255) column and TEXT, as a CLOB.

NATIVE_DATABASE_TYPES = {
    primary_key: "NUMBER(38) NOT NULL PRIMARY KEY",
    string: { name: "VARCHAR2", limit: 255 },
    text: { name: "CLOB" },
    ntext: { name: "NCLOB" },
    integer: { name: "NUMBER", limit: 38 },
    float: { name: "BINARY_FLOAT" },
    decimal: { name: "DECIMAL" },
    datetime: { name: "TIMESTAMP" },
    timestamp: { name: "TIMESTAMP" },
    timestamptz: { name: "TIMESTAMP WITH TIME ZONE" },
    timestampltz: { name: "TIMESTAMP WITH LOCAL TIME ZONE" },
    time: { name: "TIMESTAMP" },
    date: { name: "DATE" },
    binary: { name: "BLOB" },
    boolean: { name: "NUMBER", limit: 1 },
    raw: { name: "RAW", limit: 2000 },
    bigint: { name: "NUMBER", limit: 19 }
}

https://github.com/rsim/oracle-enhanced/blob/master/lib/active_record/connection_adapters/oracle_enhanced_adapter.rb

If the attribute is matching f.text_field in form use string, if it is matching f.text_area use text.

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