Introducing Crystal Programming Language

require "http/server"

class InterruptTestFirst
  include HTTP::Handler

  def call(context)
    response = call_next(context)
    puts "aa"
    response
  end
end

class InterruptTestSecond
  include HTTP::Handler

  def call(context)
    response = call_next(context)
    puts "bb"
    response
  end
end

server = HTTP::Server.new([InterruptTestFirst.new, InterruptTestSecond.new]) do |context|
  context.response.content_type = "text/plain"
  context.response.print "Hello world"
end

puts "Listening on http://0.0.0.0:8080"
server.listen(8080)

bb

aa

$ crystal init app kemal-sample
$ cd kemal-sample

dependencies:
  kemal:
    github: kemalcr/kemal
    version: 0.27.0

$ shards install

require "kemal"

  get "/hello" do |env|
    hello = "Hello World"
    render "src/views/hello.ecr"
  end

Kemal.run

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8"/>
  <title>hello</title>
</head>
<body>
  <%= hello %>
</body>
</html>

get "/path" do |env|
  # 処理
end

post "/path" do |env|
  # 処理
end

$ crystal build src/kemal-sample.cr
$ ./kemal-sample

$ createdb kemal_sample_development -O your_owner

create table articles (
  id      serial primary key,
  title   text,
  content text
);

$ psql -U your_owner -d kemal_sample_development -f sql/create_articles.sql

dependencies:
  kemal:
    github: kemalcr/kemal
    version: 0.27.0
  db:
    github: crystal-lang/crystal-db
  pg:
    github: will/crystal-pg

$ shards install

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8"/>
  <title>kemal sample</title>
  <!-- bootstrapを使用する -->
  <link
   rel="stylesheet"
   href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
  <link rel="stylesheet" href="/css/custom.css">
</head>
<body>
<header class="navbar navbar-fixed-top navbar-inverse">
  <div class="container">
    <a id="logo">sample app</a>
    <nav>
      <ul class="nav navbar-nav navbar-right">
        <li><a href="/articles">ArticleList</a></li>
        <li><a href="/articles/new">新規投稿</a></li>
      </ul>
    </nav>
  </div>
</header>
  <div class="container">
    <%= content %>
  </div>
</body>
</html>

body {
  padding-top: 60px;
}

section {
  overflow: auto;
}

textarea {
  resize: vertical;
}

.center {
  text-align: center;
}

.center h1 {
  margin-bottom: 10px;
}

h1, h2, h3, h4, h5, h6 {
  line-height: 1;
}

h1 {
  font-size: 3em;
  letter-spacing: -2px;
  margin-bottom: 30px;
  text-align: center;
}

h2 {
  font-size: 1.2em;
  letter-spacing: -1px;
  margin-bottom: 30px;
  text-align: center;
  font-weight: normal;
  color: #777;
}

p {
  font-size: 1.1em;
  line-height: 1.7em;
}

#logo {
  float: left;
  margin-right: 10px;
  font-size: 1.7em;
  color: #fff;
  text-transform: uppercase;
  letter-spacing: -1px;
  padding-top: 9px;
  font-weight: bold;
}

#logo:hover {
  color: #fff;
  text-decoration: none;
}

<h2>Article List</h2>
<table class="table table-striped">
<thead>
  <tr>
    <td>title</td>
  </tr>
<tbody>
  <% articles.each do |article| %>
  <tr>
    <td>
      <a href="/articles/<%=article["id"]? %>" target="_top">
        <%=article["title"]? %>
      </a>
    </td>
  </tr>
  <% end %>
</tbody>
</table>

<h2>新規投稿</h2>
<form method="post", action="/articles">
  <input type="text" name="title" size="10" maxlength="10" />
  <br />
  <br />
  <textarea name="content" cols="40" rows="4"></textarea>
  <br />
  <br />
  <input type="submit" value="post">
</form>

<h2>Article</h2>
<% articles.each do |article| %>
  <h3><%=article["title"] %></h3>
  <p><%=article["content"] %></p>
  <!-- 更新 -->
  <a href="/articles/<%=article["id"] %>/edit" target="_top" class="btn btn-primary">edit</a>
<br />
<% end %>

require "kemal"
require "db"
require "pg"

  database_url = "postgres://localhost:5432/kemal_sample_development"
  db = DB.open(database_url)

  ["/", "/articles"].each do |path|
    get path do |env|
      articles = [] of Hash(String, String | Int32)
      db.query("select id, title, content from articles") do |rs|
        rs.each do
          article = {} of String => String | Int32
          article["id"] = rs.read(Int32)
          article["title"] = rs.read(String)
          article["content"] = rs.read(String)
          articles << article
        end
      end
      db.close
      render "src/views/index.ecr", "src/views/application.ecr"
    end
  end

  get "/articles/new" do |env|
    render "src/views/articles/new.ecr", "src/views/application.ecr"
  end

  post "/articles" do |env|
    # env.params.bodyでformのvalueを取得できます
    title_param = env.params.body["title"]
    content_param = env.params.body["content"]
    params = [] of String
    params << title_param
    params << content_param
    # update, insert, deleteは以下のようにexecでアップデートを実行します
    db.exec("insert into articles(title, content) values($1::text, $2::text)", params)
    db.close
    env.redirect "/"
  end

  get "/articles/:id" do |env|
    articles = [] of Hash(String, String | Int32)
    article = {} of String => String | Int32
    id = env.params.url["id"].to_i32
    params = [] of Int32
    params << id
    sql = "select id, title, content from articles where id = $1::int8"
    article["id"], article["title"], article["content"] =
      db.query_one(sql, params, as: {Int32, String, String})
    articles << article
    db.close
    render "src/views/articles/show.ecr", "src/views/application.ecr"
  end

      db.query("select id, title, content from articles") do |rs|
        rs.each do
          article = {} of String => String | Int32
          article["id"] = rs.read(Int32)
          article["title"] = rs.read(String)
          article["content"] = rs.read(String)
          articles << article
        end
      end

  sql = "select id, title, body from articles where id = $1::int8"
  article["id"], article["title"], article["body"] =
    db.query_one(sql, params, as: {Int32, String, String})

$1::int8

db.exec("insert into articles(title, content) values($1::text, $2::text)", params)

render "src/views/articles/show.ecr", "src/views/application.ecr"

<h2>投稿編集</h2>
<% articles.each do |article| %>
<form method="post", action="/articles/<%=article["id"] %>">
  <!--
   hiddenフィールドにname="_method"、
   valueにputを設定する。
  -->
  <input type="hidden", name="_method", value="put" />
  <input type="text" name="title" size="10" maxlength="10" value="<%=article["title"] %>" />
  <br />
  <br />
  <textarea name="content" cols="40" rows="4"><%=article["content"] %></textarea>
  <br />
  <br />
  <input type="submit" value="edit" class="btn btn-primary">
</form>
<% end %>

  get "/articles/:id/edit" do |env|
    articles = [] of Hash(String, String | Int32)
    article = {} of String => String | Int32
    id = env.params.url["id"].to_i32
    params = [] of Int32
    params << id
    sql = "select id, title, content from articles where id = $1::int8"
    article["id"], article["title"], article["content"] =
      db.query_one(sql, params, as: {Int32, String, String})
    articles << article
    db.close
    render "src/views/articles/edit.ecr", "src/views/application.ecr"
  end

  put "/articles/:id" do |env|
    id = env.params.url["id"].to_i32
    title_param = env.params.body["title"]
    content_param = env.params.body["content"]
    params = [] of String | Int32
    params << title_param
    params << content_param
    params << id
    db.exec("update articles set title = $1::text, content = $2::text where id = $3::int8", params)
    db.close
    env.redirect "/articles/#{id}"
  end

delete "/articles/:id" do |env|
  id = env.params.url["id"].to_i32
  params = [] of Int32
  params << id
  db.exec("delete from articles where id = $1::int8", params)
  db.close
  env.redirect "/"
end

database_url = "postgres://localhost:5432/kemal_sample_development"
db = DB.open(database_url)
db.transaction do |tx|
  result = tx.connection.exec("insert into articles(title, content) values('hoge', 'huga')")
  # エラー時
  if !result
    tx.rollback
  else
    tx.commit
  end
end

dependencies:
  mysql:
    github: crystal-lang/crystal-mysql

require "db"
require "mysql"

DB.open "mysql://root@localhost/test" do |db|
  # 実行系
  db.exec "insert into contacts values (?, ?)", "John", 30
end