[RUBY] [Rails / Heroku] Error resolution procedure after push

Status

• Additional implementation in application in development environment (implementation of comment function)

• Push to Heroku where you deploy

• Error when trying to post a comment on the Heroku app

environment

• macOS Catalina 10.15.6

• ruby 2.6.5

• Rails 6.0.3.4

• MySQL : 5.6.47

Action procedure

1. Check the log in the terminal

When you operate the app on Heroku, you can check the log by typing the command in the terminal.

terminal

% heroku logs --tail --app app name

# --tail is an option to display the last 10 lines

Here is an excerpt of the error part after execution.

Next, we will deepen the error part.

2. Read the error

The reason for the error is written in the image above.

1. Completed 500 Internal Server Error

2. ActiveRecord::StatementInvalid (Mysql2::Error: Table 'heroku_***.comments' doesn't exist):

1 indicates that the error is a server-side error. This '500' is called "HTTP status code" and expresses the meaning of the response in HTTP communication. To introduce some ...

--200: Normal response

--302: Perform redirect

--404: Request to a non-existent URL

2 is a hint to solve this error.

--ActiveRecord :: StatementInvalid: Error when using Active Record

--Table'*** .comments' doesn't exist: comments The table does not exist

The comment feature worked fine in the development environment, and I got an error when trying to post a comment on Heroku. And looking at this error statement, the following are possible causes of the error:

I haven't created a comment table on Heroku </ b>.

(Control +After exiting the log screen with C)

% heroku run rails db:migrate