feat: Add support for custom DialInfo (#12, #15)

* Add support for custom DialInfo

Lets users provide their own DialInfo if they need to specify more configuration than mongodm's config allows

* Fix minor syntax error

* chore: Update readme for custom dialinfo and add test

* chore: Add reference link to mgo.DialInfo

README.md

@@ -89,6 +89,42 @@ Load your localisation file and parse it until you get a `map[string]string` typ
 		DatabaseName: "mongodm_sample",
 		DatabaseUser: "admin",
 		DatabasePassword: "admin",
+		// The option `DatabaseSource` is the database used to establish 
+		// credentials and privileges with a MongoDB server. Defaults to the value
+		// of `DatabaseName`, if that is set, or "admin" otherwise.
+		DatabaseSource: "admin",
+		Locals:       localMap["en-US"],
+	}
+
+	connection, err := mongodm.Connect(dbConfig)
+
+	if err != nil {
+		fmt.Println("Database connection error: %v", err)
+	}
+```
+
+You can also pass a custom DialInfo from mgo ([`*mgo.DialInfo`](https://godoc.org/labix.org/v2/mgo#DialInfo)). If used, all config attributes starting with `Database` will be ignored:
+
+```go
+	file, err := ioutil.ReadFile("locals.json")
+
+	if err != nil {
+		fmt.Printf("File error: %v\n", err)
+		os.Exit(1)
+	}
+
+	var localMap map[string]map[string]string
+	json.Unmarshal(file, &localMap)
+
+	dbConfig := &mongodm.Config{
+		DialInfo: &mgo.DialInfo{
+			Addrs:    []string{"127.0.0.1"},
+			Timeout:  3 * time.Second,
+			Database: "mongodm_sample",
+			Username: "admin",
+			Password: "admin",
+			Source:   "admin",
+		},
 		Locals:       localMap["en-US"],
 	}
 

mongodm.go

@@ -102,7 +102,8 @@ type (
 		DatabaseName     string
 		DatabaseUser     string
 		DatabasePassword string
-		Source string
+		DatabaseSource   string
+		DialInfo         *mgo.DialInfo
 		Locals           map[string]string
 	}
 
@@ -295,13 +296,19 @@ func (self *Connection) Open() (err error) {
 		}
 	}()
 
-	info := &mgo.DialInfo{
-		Addrs:    self.Config.DatabaseHosts,
-		Timeout:  3 * time.Second,
-		Database: self.Config.DatabaseName,
-		Username: self.Config.DatabaseUser,
-		Password: self.Config.DatabasePassword,
-		Source: self.Config.Source,
+	var info *mgo.DialInfo
+
+	if self.Config.DialInfo == info {
+		info = &mgo.DialInfo{
+			Addrs:    self.Config.DatabaseHosts,
+			Timeout:  3 * time.Second,
+			Database: self.Config.DatabaseName,
+			Username: self.Config.DatabaseUser,
+			Password: self.Config.DatabasePassword,
+			Source:   self.Config.DatabaseSource,
+		}
+	} else {
+		info = self.Config.DialInfo
 	}
 
 	session, err := mgo.DialWithInfo(info)

mongodm_test.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"testing"
 
+	mgo "gopkg.in/mgo.v2"
 	"gopkg.in/mgo.v2/bson"
 )
 
@@ -16,6 +17,7 @@ const (
 	DBName              string = "mongodm_test"
 	DBUser              string = "admin"
 	DBPass              string = "admin"
+	DBSource            string = "admin"
 	DBTestCollection    string = "_testCollection"
 	DBTestRelCollection string = "_testRelationCollection"
 )
@@ -76,8 +78,8 @@ func TestConnection(t *testing.T) {
 		// with a MongoDB server. Defaults to the value of Database, if that is
 		// set, or "admin" otherwise.
 		// see https://godoc.org/labix.org/v2/mgo#DialInfo
-		Source:           "admin",
-		Locals:           localMap["en-US"],
+		DatabaseSource: "admin",
+		Locals:         localMap["en-US"],
 	}
 
 	db, err := Connect(dbConfig)
@@ -101,6 +103,31 @@ func TestConnection(t *testing.T) {
 	}
 }
 
+func TestConnectionWithCustomDialInfo(t *testing.T) {
+
+	var localMap map[string]map[string]string
+	json.Unmarshal(localsFile, &localMap)
+
+	dbConfig := &Config{
+		DialInfo: &mgo.DialInfo{
+			Addrs:    []string{DBHost},
+			Database: DBName,
+			Username: DBUser,
+			Password: DBPass,
+			Source:   DBSource,
+		},
+		Locals: localMap["en-US"],
+	}
+
+	_, err := Connect(dbConfig)
+
+	if err != nil {
+
+		t.Error("DB: Connection error", err)
+
+	}
+}
+
 func TestConnectionWithoutExtendedConfig(t *testing.T) {
 
 	dbConfig := &Config{