diff --git a/crud.go b/crud.go
index a7f7ac4..67fb175 100644
--- a/crud.go
+++ b/crud.go
@@ -27,7 +27,7 @@ func (e *ErrorWithStack) Stack() string {
 }
 
 // CreateDocument creates a document from specified model
-func CreateDocument(db *Database, m ModelInterface) error {
+func (db *Database) CreateDocument(m ModelInterface) error {
 	m.PrepareInsert()
 
 	c := db.C(GetCollectionName(m))
@@ -37,7 +37,7 @@ func CreateDocument(db *Database, m ModelInterface) error {
 }
 
 // ReadDocument gets one document via its id
-func ReadDocument(db *Database, m ModelInterface, selector bson.M) error {
+func (db *Database) ReadDocument(m ModelInterface, selector bson.M) error {
 	c := db.C(GetCollectionName(m))
 
 	q := c.FindId(m.GetID())
@@ -136,7 +136,7 @@ func idToObjectID(filter interface{}) {
 }
 
 // ReadCollection gets the filtered collection of the model
-func ReadCollection(db *Database, results interface{}, filter bson.M, selector bson.M, offset int, limit int, sort []string, pipelineModifier PipelineModifierFunction) (err error) {
+func (db *Database) ReadCollection(results interface{}, filter bson.M, selector bson.M, offset int, limit int, sort []string, pipelineModifier PipelineModifierFunction) (err error) {
 	defer func() {
 		if r := recover(); r != nil {
 			err = &ErrorWithStack{Message: fmt.Sprintf("%v", r), StackTrace: string(debug.Stack())}
@@ -243,7 +243,7 @@ func ReadCollection(db *Database, results interface{}, filter bson.M, selector b
 }
 
 // ReadCollectionCount gets the count of elements in filtered collection
-func ReadCollectionCount(db *Database, m ModelInterface, filter bson.M) (count int, err error) {
+func (db *Database) ReadCollectionCount(m ModelInterface, filter bson.M) (count int, err error) {
 	defer func() {
 		if r := recover(); r != nil {
 			err = fmt.Errorf("%v", r)
@@ -255,7 +255,7 @@ func ReadCollectionCount(db *Database, m ModelInterface, filter bson.M) (count i
 }
 
 // UpdateDocument updates a document from specified model
-func UpdateDocument(db *Database, m ModelInterface, changes bson.M) error {
+func (db *Database) UpdateDocument(m ModelInterface, changes bson.M) error {
 	m.PrepareUpdate()
 	changes["updateTime"] = time.Now()
 
@@ -266,7 +266,7 @@ func UpdateDocument(db *Database, m ModelInterface, changes bson.M) error {
 }
 
 // UpsertDocument updates a document from specified model or inserts it, of not found
-func UpsertDocument(db *Database, m ModelInterface, changes bson.M) error {
+func (db *Database) UpsertDocument(m ModelInterface, changes bson.M) error {
 	m.PrepareUpdate()
 	changes["updateTime"] = time.Now()
 
@@ -277,7 +277,7 @@ func UpsertDocument(db *Database, m ModelInterface, changes bson.M) error {
 }
 
 // DeleteDocument deletes one document via its id
-func DeleteDocument(db *Database, m ModelInterface) error {
+func (db *Database) DeleteDocument(m ModelInterface) error {
 	c := db.C(GetCollectionName(m))
 
 	err := c.RemoveId(m.GetID())
@@ -286,7 +286,7 @@ func DeleteDocument(db *Database, m ModelInterface) error {
 }
 
 // DeleteDocuments deletes documents found by filter
-func DeleteDocuments(db *Database, m ModelInterface, filter bson.M) (removed int, err error) {
+func (db *Database) DeleteDocuments(m ModelInterface, filter bson.M) (removed int, err error) {
 	c := db.C(GetCollectionName(m))
 
 	info, err := c.RemoveAll(filter)
diff --git a/lookup.go b/lookup.go
index a118993..e1fed59 100644
--- a/lookup.go
+++ b/lookup.go
@@ -8,7 +8,7 @@ import (
 )
 
 // Lookup extends results with data for inline structs
-func Lookup(db *Database, structField string, results interface{}, selector bson.M) error {
+func (db *Database) Lookup(structField string, results interface{}, selector bson.M) error {
 
 	t := reflect.TypeOf(results)
 	v := reflect.ValueOf(results)
@@ -122,7 +122,7 @@ func Lookup(db *Database, structField string, results interface{}, selector bson
 		return fmt.Errorf("ID type in objects struct %+v is not bson.ObjectId", fieldType)
 	}
 
-	err := ReadCollection(db, objectResults, sQuery, selector, 0, 0, nil, nil)
+	err := db.ReadCollection(objectResults, sQuery, selector, 0, 0, nil, nil)
 	if err != nil {
 		panic(err)
 	}
diff --git a/setup.go b/setup.go
index 878c8c9..1df161a 100644
--- a/setup.go
+++ b/setup.go
@@ -9,7 +9,7 @@ import (
 )
 
 // EnsureIndex ensured mongodb index reflecting model struct index tag
-func EnsureIndex(db *Database, m ModelInterface) error {
+func (db *Database) EnsureIndex(m ModelInterface) error {
 	colName := GetCollectionName(m)
 	col := db.C(colName)
 
diff --git a/validator.go b/validator.go
index e9f321f..1ac7e5d 100644
--- a/validator.go
+++ b/validator.go
@@ -6,7 +6,7 @@ import (
 )
 
 // ValidateObject validates object via validator tag and custom method
-func ValidateObject(db *Database, m ModelInterface, changes bson.M) error {
+func (db *Database) ValidateObject(m ModelInterface, changes bson.M) error {
 	// first validate via struct tag
 	validator := validator.New(&validator.Config{
 		TagName: "validator",