Dj/271 maintain one database connection (#274)

* fix multiple connection issue #271

* create a single connection per registered adapter

shard.yml

@@ -2,7 +2,7 @@ name: granite
 
 version: 0.13.0
 
-crystal: 0.25.1
+crystal: 0.26.0
 
 authors:
   - drujensen <drujensen@gmail.com>

spec/adapter/adapters_spec.cr

@@ -16,7 +16,7 @@ describe Granite::Adapters do
 
     it "should disallow multiple adapters with the same name" do
       expect_raises(Exception, "Adapter with name 'mysql' has already been registered.") do
-        Granite::Adapters << Granite::Adapter::Pg.new({name: "mysql", url: "PG_DATABASE_URL"})
+        Granite::Adapters << Granite::Adapter::Pg.new({name: "mysql", url: ENV["PG_DATABASE_URL"]})
       end
     end
 

spec/spec_helper.cr

@@ -1,9 +1,12 @@
+require "spec"
+require "mysql"
+require "pg"
+require "sqlite3"
+
 Granite::Adapters << Granite::Adapter::Mysql.new({name: "mysql", url: ENV["MYSQL_DATABASE_URL"]})
 Granite::Adapters << Granite::Adapter::Pg.new({name: "pg", url: ENV["PG_DATABASE_URL"]})
 Granite::Adapters << Granite::Adapter::Sqlite.new({name: "sqlite", url: ENV["SQLITE_DATABASE_URL"]})
 
-require "spec"
-
 module GraniteExample
   ADAPTERS = ["pg", "mysql", "sqlite"]
 end

src/adapter/base.cr

@@ -7,14 +7,16 @@ require "db"
 abstract class Granite::Adapter::Base
   getter name : String
   getter url : String
+  private property database : DB::Database
 
   def initialize(connection_hash : NamedTuple(url: String, name: String))
     @name = connection_hash[:name]
     @url = connection_hash[:url]
+    @database = DB.open(@url)
   end
 
   def open(&block)
-    yield DB.open(@url)
+    yield database
   end
 
   def log(query : String, params = [] of String) : Nil