Railsのエラー『ActionController::ParameterMissing: param is missing or the value is empty』の解決方法

# app/controllers/posts_controller.rb
class PostsController < ApplicationController
  def create
    @post = Post.new(post_params)
    if @post.save
      render json: @post, status: :created
    else
      render json: @post.errors, status: :unprocessable_entity
    end
  end

  private

  def post_params
    params.require(:post).permit(:title, :content)
  end
end

# 正しいリクエスト例
{
  "post": {
    "title": "Hello World",
    "content": "This is a sample post."
  }
}

# app/views/posts/new.html.erb
<%= form_with model: @post do |form| %>
  <%= form.text_field :title %>
  <%= form.text_area :content %>
  <%= form.submit %>
<% end %>

# 正しいAPIリクエスト例
{
  "post": {
    "title": "Hello World",
    "content": "This is a sample post."
  }
}

# app/controllers/application_controller.rb
class ApplicationController < ActionController::Base
  rescue_from ActionController::ParameterMissing, with: :handle_parameter_missing

  private

  def handle_parameter_missing(exception)
    render json: { error: exception.message }, status: :bad_request
  end
end

require 'logger'

logger = Logger.new("parameter_missing_errors.log")

begin
  # リクエスト処理
rescue ActionController::ParameterMissing => e
  logger.error("ParameterMissing: #{e.message}")
end

# app/controllers/posts_controller.rb
class PostsController < ApplicationController
  def create
    @post = Post.new(post_params)
    if @post.save
      render json: @post, status: :created
    else
      render json: @post.errors, status: :unprocessable_entity
    end
  end

  private

  def post_params
    params.fetch(:post, {}).permit(:title, :content)
  end
end