Add model interface (#1808)

model/model.go

@@ -0,0 +1,51 @@
+// Package model is an interface for data modelling
+package model
+
+import (
+	"github.com/micro/go-micro/v2/store"
+	"github.com/micro/go-micro/v2/sync"
+)
+
+// Model provides an interface for data modelling
+type Model interface {
+	// Initialise options
+	Init(...Option) error
+	// NewEntity creates a new entity to store or access
+	NewEntity(name string, value interface{}) Entity
+	// Create a value
+	Create(Entity) error
+	// Read values
+	Read(...ReadOption) ([]Entity, error)
+	// Update the value
+	Update(Entity) error
+	// Delete an entity
+	Delete(...DeleteOption) error
+	// Implementation of the model
+	String() string
+}
+
+type Entity interface {
+	// Unique id of the entity
+	Id() string
+	// The value associated with the entity
+	Value() interface{}
+	// Attributes of the enity
+	Attributes() map[string]interface{}
+}
+
+type Options struct {
+	// for locking
+	Sync sync.Sync
+	// for storage
+	Store store.Store
+}
+
+type Option func(o *Options)
+
+type ReadOptions struct{}
+
+type ReadOption func(o *ReadOptions)
+
+type DeleteOptions struct{}
+
+type DeleteOption func(o *DeleteOptions)