Rails seed.db syntax - ruby-on-rails

Question

I have this code. The first and second command for rails work good, but "project.todos << todo" part ruby interpreter treats like error.
NoMethodError: undefined method `todos' for nil:NilClass
How can i fix it? When i put in seeds.rb text like this, all good, but with code it not work:
#work
project = Project.create title: "Family"
todo = Todo.create text: "Buy milk", isCompleted: true
project.todos << todo
#code
require 'yaml'
yhash = YAML.load_file(File.open("#{Rails.root}/db/seeds.yml"))
yhash.each do |key, value|
value.each do |k, v|
k.each do |ke, proj|
if proj.class.name == 'String'
project = Project.create title: proj
elsif proj.class.name == 'Array'
proj.each do |todo|
i = 0
tmp = ''
todo.each do |to|
to.each do |t|
if i == 0
i = 1
elsif i == 2
i = 3
elsif i == 1
tmp = t
i = 2
elsif i == 3
if t == false
bool = 'false'
else
bool = 'true'
end
todo = Todo.create text: tmp, isCompleted: bool
project.todos << todo
i = 0
tmp = ''
end
end
end
end
end
end
end
end

Answer 1

Short answer
You really should change your YAML structure, it would make everything much easier.
---
projects:
- title: Family
todos:
- text: Buy milk
is_completed: true
- text: Todo2
is_completed: false
- title: Project2
todos:
- text: Todo3
is_completed: true
- text: Todo4
is_completed: false
You could parse it in a few lines :
yaml = YAML.load(File.read('test.yaml'))
yaml['projects'].each do |project|
title = project['title']
p title
# Create project here
project['todos'].each do |todo|
p todo
# Create todo here
# Add todo to project
end
end
NoMethodError
NoMethodError: undefined method 'todos' for nil:NilClass
means that the object on which todos is called (project) isn't defined.
Indeed, project isn't defined, but proj is, so you should create a Project called project first.
Naming objects
To avoid confusion :
project_name could be a string containing the project name
project_names could be an array of project names
project could be a Project object
todos could be an Array of Todos
Your code indicates that proj is used for different purposes :
project = Project.create title: proj
proj.each do |todo|
Those 2 projs should be different objects with different variable names, and should be initialized separately.
It's easy to write nested hashes in YAML, one hash could represent Projects, the other could represent Todos.
Block variables
If you create a Project instance called project inside a loop during the first iteration, it will not be available to the next iterations :
[1, 2, 3].each do |i|
if i==1
project = "my project"
end
p i
p project
end
# 1
# "my project"
# 2
# nil
# 3
# nil
If you want a project variable to be available to all iterations, you should create it outside of the loop :
project = "my project"
[1, 2, 3].each do |i|
p i
p project
end
# 1
# "my project"
# 2
# "my project"
# 3
# "my project"
Another possibility would be to use #project instead of project :
[1,2,3].each do |i|
if i==1
#project = "my project"
end
p i
p #project
end
# 1
# "my project"
# 2
# "my project"
# 3
# "my project"
case
Instead of :
if proj.class.name == 'String'
project = Project.create title: proj
elsif proj.class.name == 'Array'
You could use :
case proj
when String
# proj is a String
when Array
# proj is an Array
end