P5-6517 add market resource (#32)

api/models/market.py

@@ -2,6 +2,7 @@
 
 from api.extensions import db
 from .product import Currencies
+from sqlalchemy.orm import validates
 
 
 class Market(db.Model):
@@ -10,6 +11,16 @@ class Market(db.Model):
     id = db.Column(db.Integer, primary_key=True)
     name = db.Column(db.String(255))
 
+    @validates("name")
+    def validate_name(self, key, value):
+        raise ValueError("Name can not be modified")
+
+    def to_json(self):
+        return {
+            "id": self.id,
+            "name": self.name,
+        }
+
 
 class PriceAdjustments(db.Model):