Crystal RethinkDB

This is a RethinkDB Driver for the Crystal Language.

Installation

Add this to your application's shard.yml:

dependencies:
  rethinkdb:
    github: kingsleyh/crystal-rethinkdb

Usage

This library is meant to be compatible with RethinkDB's Ruby API. Thus, all official documentation should be valid here. If you find something that behaves differently, please open an issue.

require "rethinkdb"
include RethinkDB::Shortcuts

# Let’s connect and create a table:

conn = r.connect(host: "localhost")
r.db("test").table_create("tv_shows").run(conn)

# Now, let’s insert some JSON documents into the table:

r.table("tv_shows").insert([
  {name: "Star Trek TNG", episodes: 178},
  {name: "Battlestar Galactica", episodes: 75}
]).run(conn)

# We’ve just inserted two rows into the tv_shows table. Let’s verify the number of rows inserted:

pp r.table("tv_shows").count().run(conn)

# Finally, let’s do a slightly more sophisticated query. Let’s find all shows with more than 100 episodes.

p r.table("tv_shows").filter {|show| show["episodes"] > 100 }.run(conn).to_a

# As a result, we of course get the best science fiction show in existence.

Connecting as a user

If you made a user called bob with password secret in the rethinkdb system table users e.g.:

r.db('rethinkdb').table('users').insert({id: 'bob', password: 'secret'})

require "rethinkdb"
include RethinkDB::Shortcuts

conn = r.connect(host: "localhost", db: "my_database", user: "bob", password: "secret")

Read more about users and permissions here: https://rethinkdb.com/docs/permissions-and-accounts/

Useful Queries

Here are some more complex queries - mostly as a reminder to myself on how to do various more complicated things:

Something to note is that depending on the query you write you could get back one of these 3 things:

RethinkDB::QueryResult
RethinkDB:Cursor
RethinkDB::Array(RethinkDB::QueryResult)

Inserting

r.table("users").insert({
                      name: name, email: email, password: password,
                      activeChannel: {} of String => String,
                      channels: [] of String, groups: [] of String,
                      isOnline: false
                      }
                    ).run(@connection)

r.table("messages").insert({channelId: channelId, userId: userId, content: content, date: r.now.to_iso8601}).run(@connection)

Finding All

r.table("users").map{|u|
         {id: u["id"], name: u["name"], isOnline: u["isOnline"]}
      }.run(@connection) }

r.table("users").filter{|u| r.expr(u["groups"]).contains(groupId) }.map{|u|
         {id: u["id"], name: u["name"], isOnline: u["isOnline"]}
      }.run(@connection)

r.table("groups").map{|g|
         {id: g["id"], name: g["name"], landingChannel: r.table("channels").filter({isLanding: true, groupId: g["id"]})[0]["id"]}
      }.run(@connection)

r.table("users").filter({id: userId}).map{|user|
                        {
                         channels: r.table("channels").filter{|ch| ch["groupId"] == groupId}.coerce_to("array"),
                         activeChannel: r.branch(user["activeChannel"].has_fields("channelId"),
                                          {groupId: user["activeChannel"]["groupId"], channelId: user["activeChannel"]["channelId"], name: r.table("channels").get(user["activeChannel"]["channelId"])["name"]},
                                          {groupId: "", channelId: "", name: ""}),
                         groupId: r.table("groups").get(groupId)["id"],
                         name: r.table("groups").get(groupId)["name"]
                         }
                       }.run(@connection)

Finding One

r.table("users").get(userId).run(@connection)

  r.table("users").filter({id: userId}).map{|user|
                        {
                        channels: r.table("channels").filter{|ch| r.expr(user["channels"]).contains(ch["id"])}.filter{|ch| ch["groupId"] == groupId}.coerce_to("array"),
                        groups: r.table("groups").filter{|g| r.expr(user["groups"]).contains(g["id"])}.map{|g| {id: g["id"], name: g["name"], landingChannel: r.table("channels").filter({isLanding: true, groupId: g["id"]})[0]["id"]}}.coerce_to("array"),
                        messages: r.table("messages").filter{|m| m["channelId"] == channelId }.map{|m| {messageId: m["id"], userId: m["userId"], name: r.table("users").get(m["userId"])["name"], content: m["content"], date: m["date"]} }.coerce_to("array"),
                        channel: r.table("channels").get(channelId),
                        group: r.table("groups").get(groupId),
                        userIsOnline: user["isOnline"]
                        }
                      }.run(@connection).to_a.first

Updates

r.table("users").get(userId).update({isOnline: isOnline}).run(@connection)

r.table("users").get(userId).update{|u|
        {channels: u.get_field("channels").set_insert(channelId),
         groups: u.get_field("groups").set_insert(groupId),
         activeChannel: {groupId: groupId, channelId: channelId}
        }
      }.run(@connection) }

r.table("users").get(userId).update{|u| {groups: u.get_field("groups").set_insert(groupId)}}.run(@connection)

Creating a database

def recreate_database
  puts "dropping database: #{@env.database.name}"

  begin
    r.db_drop(@env.database.name).run( @connection)
  rescue ex
    puts ex.message
  end

  puts "creating database: #{@env.database.name}"
  r.db_create(@env.database.name).run(@connection)

  # add tables
  puts "adding tables: users, groups, channels, messages"
  r.db(@env.database.name).table_create("users").run(@connection)
  r.db(@env.database.name).table_create("groups").run(@connection)
  r.db(@env.database.name).table_create("channels").run(@connection)
  r.db(@env.database.name).table_create("messages").run(@connection)

  puts "done"
end