An error occurred in the free course of RubyOnRails Udemy, solved it, and went through to the end

An error occurred in the free course of RubyOnRails Udemy, solved it, and went through to the end

For those of you who have just started learning RubyOnRails and have taken the following free Udemy courses, but have stumbled on an error and couldn't complete it to the end, we will share the errors and solutions we have experienced.

[You can do it in as little as 30 minutes!] Introduction to Ruby on Rails: Easy for beginners! Browser

When the error occurs-1

1. Course of "14. Addition of image files and addition of editing functions"

2. An error occurred in the terminal when I typed "rake db: migrate" in the terminal.

3. I also got the error "ActiveRecord :: PendingMigrationError" on localhost: 3000.

Cause, solution-1

The reason is that'paperclip' depends on the version of rails. After careful confirmation, it was stated that the course was based on Ruby on Rails 5.2. For me, PaizaCloud was based on Ruby on Rails 6 at the moment.

1. Hit "gem list rails" in the terminal to check the rails version.

• The version in my case is 　6.0.2.1, 　5.0.7.2, 　5.0.6 was.

2. Create a new project.

• As a course, let's return to "9. Creating a project".

3. In the terminal, type "rails _ (version) _ new boardgame-app --database = mysql" to create a project that uses RubyOnRails 5 series.

• In my case, I used RubyOnRails 5.0.7.2.

Operation check-1

1. Let's proceed according to the course.

2. When I checked the operation in the course of "14. Adding image files and adding editing functions", it proceeded without any error. There is no problem with localhost: 3000.

When the error occurs-2

1. Course of "14. Addition of image files and addition of editing functions"

Cause, solution-2

The cause is unknown, but unlike the others, it seems that the cause is using "<% = from ...".

1. Rewrite "<% = from ..." to "<% = f ...".

Operation check-2

1. It was displayed without any problem on localhost: 3000.

** I think Laravel is the same, but there were many unexpected deficiencies depending on the version (the description method was different, the package could not be used, etc.). If you encounter an error, don't be frustrated, and I hope everyone will work together to resolve it. ** **

Free courses may not allow you to ask questions to the instructor even if you encounter an error. I hope this post will be a driving force for those who are starting to learn Ruby On Rails to go through to the end without giving up.