Rails serializing cannot insert value

Question

I created migration

add_column :users, :read_post_id, :integer

Added to the user model

serialize :read_post_id  , Array

Edit: if I use

<%=  User.find(current_user.id).read_post_id << 3 %>

I get an output [3]. But this value is only temporary and is not saved. How to save it ? I read Rails serialized integer attribute in params, but not saving into model instance which says serialized attributes cannot be integer. Changed it to text. After

<%=  User.find(current_user.id).read_post_id << ["3","5"] %>
<%=  User.find(current_user.id).read_post_id.count %>
<%=  User.find(current_user.id).save %>

I do receive an ouput [["3", "5"]] 0 true

So basicly nothing has changed

e_a_o · Accepted Answer · 2017-11-26 22:10:55Z

1

You will need to change the data type of read_post_id column to :text instead of :integer.

Why? Because Active Record serializes any object in text columns using YAML, not integer columns. The serialized data need to go into a text column not integer column. See AR doc: Saving arrays, hashes, and other non-mappable objects in text columns

To change the column type, create a new migration file that looks like this:

class ChangeReadPostIdColumnType < ActiveRecord::Migration
  def change
    change_column :users, :read_post_id, :text
  end
end

A quick unsolicited suggestion, if read_post_id is going to be serialized into an array of ids, why don't you name it read_post_ids for easy readability?

You can use the snippet below to change the column name and the column type in one migration file:

class ChangeReadPostIdColumnNameAndType < ActiveRecord::Migration
  def change
    change_column :users, :read_post_id, :text
    rename_column :users, :read_post_id, :read_post_ids
  end
end

answered Nov 26, 2017 at 22:10

e_a_o

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6 Comments

John Over a year ago

You may have not seen my post edit, but I did the migration from integer to text and it is still not working @esther

e_a_o Over a year ago

@John okay, just seeing the updated posted. Can you use the = operator instead of the << operator? Also can you update the post to show the full console logs? Lastly, you can just make use of current_user.read_post_id instead of User.find(current_user.id).read_post_id

John Over a year ago

Tried = and it does same as <<. Also tried current_user - undefined method `read_post_id=' And probably this is the problem. Do I have to specify read_post_id somewhere else i.e in the controller ? @esther

e_a_o Over a year ago

@John Oh, have you tried updating the user object in the controller or model instead of in the views/erb file? <%= ideally should only be used for display. What does your current_user method look like? I assumed that this returns a user object?

John Over a year ago

def current_user login_from_session || login_from_basic_auth end @esther

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