App rolling back transactions and I don't know why - sql

Question

I am curious as to why my Rails app is rolling back transactions to DB without it being asked to.
Puma log:
Started POST "/posts" for 127.0.0.1 at 2019-01-05 00:32:32 -0500
Processing by PostsController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"1AlwhyE0VY87oSyCyjmrzgxinJ7+t1TfoYYEDXvfl0pGd4DKE842KXHroFWgtXeusOgt+ZApHmB+e40qliTPjQ==", "post"=>{"title"=>"test", "category_id"=>"4", "body"=>"test"}, "commit"=>"Create Post"}
User Load (0.3ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT ? [["id", 12], ["LIMIT", 1]]
↳ app/controllers/application_controller.rb:7
(0.2ms) begin transaction
↳ app/controllers/posts_controller.rb:14
Category Load (0.2ms) SELECT "categories".* FROM "categories" WHERE "categories"."id" = ? LIMIT ? [["id", 4], ["LIMIT", 1]]
↳ app/controllers/posts_controller.rb:14
(0.1ms) rollback transaction
↳ app/controllers/posts_controller.rb:14
Redirected to http://localhost:3000/posts
Completed 302 Found in 18ms (ActiveRecord: 0.8ms)
Post controller:
class PostsController < ApplicationController
before_action :require_user
def index
#posts = Post.all
end
def new
#post = Post.new
#categories = Category.all
end
def create
#post = Post.new(post_params)
if #post.save(post_params)
#post.author = current_user.username
flash[:success] = "Post created."
redirect_to post_path(#post.id)
else
flash[:danger] = "Post not created. Redirecting to main page....."
redirect_to posts_path
end
end
View:
<%= form_for #post do |f| %>
<%= f.label :title, "Title of Post" %>
<%= f.text_field :title, class: "form-control" %>
<%= f.label :body, "Post Text" %>
<%= f.text_area :body, class: "form-control" %>
<%= f.submit "Create Post", class: "btn btn-info"%>
<% end %>

Answer 1

You're likely to have validation of the presence of the author field. Since it's set incorrectly in the create method, you have the transaction rolled back:
class PostsController < ApplicationController
...
def create
#post = Post.new(post_params)
if #post.save(post_params)
#post.author = current_user.username
flash[:success] = "Post created."
redirect_to post_path(#post.id)
...
end
In order to have author assigned and saved in the db, you need to assign the author before the saving:
class PostsController < ApplicationController
...
def create
#post = Post.new(post_params)
#post.author = current_user.username
if #post.save(post_params)
flash[:success] = "Post created."
redirect_to post_path(#post.id)
...
end

Answer 2

Depending on the version of Rails you have, and if you are using Strong Parameters, you must whitelist your parameters in the controller.
Example from docs:
private
# Using a private method to encapsulate the permissible parameters
# is just a good pattern since you'll be able to reuse the same
# permit list between create and update. Also, you can specialize
# this method with per-user checking of permissible attributes.
def person_params
params.require(:person).permit(:name, :age)
end