Add default __repr__ for Model class

flask_sqlalchemy/__init__.py

@@ -30,7 +30,7 @@
 from sqlalchemy.orm.exc import UnmappedClassError
 from sqlalchemy.orm.session import Session as SessionBase
 
-from ._compat import itervalues, string_types, xrange
+from ._compat import itervalues, string_types, xrange, to_str
 
 __version__ = '2.2.1'
 
@@ -662,6 +662,10 @@ class Model(object):
     #: Equivalent to ``db.session.query(Model)`` unless :attr:`query_class` has been changed.
     query = None
 
+    def __repr__(self):
+        pk = ', '.join(to_str(value) for value in inspect(self).identity)
+        return '<{0} {1}>'.format(type(self).__name__, pk)
+
 
 class SQLAlchemy(object):
     """This class is used to control the SQLAlchemy integration to one

flask_sqlalchemy/_compat.py

@@ -10,7 +10,6 @@
 """
 import sys
 
-
 PY2 = sys.version_info[0] == 2
 
 
@@ -25,6 +24,15 @@ def itervalues(d):
 
     string_types = (unicode, bytes)
 
+    def to_str(x, charset='utf8', errors='strict'):
+        if x is None or isinstance(x, str):
+            return x
+
+        if isinstance(x, unicode):
+            return x.encode(charset, errors)
+
+        return str(x)
+
 else:
     def iteritems(d):
         return iter(d.items())
@@ -34,4 +42,13 @@ def itervalues(d):
 
     xrange = range
 
-    string_types = (str, )
+    string_types = (str,)
+
+    def to_str(x, charset='utf8', errors='strict'):
+        if x is None or isinstance(x, str):
+            return x
+
+        if isinstance(x, bytes):
+            return x.decode(charset, errors)
+
+        return str(x)

tests/test_model_class.py

@@ -1,4 +1,6 @@
+# coding=utf8
 import flask_sqlalchemy as fsa
+from flask_sqlalchemy._compat import to_str
 
 
 def test_custom_query_class(app):
@@ -11,3 +13,32 @@ class SomeModel(db.Model):
         id = db.Column(db.Integer, primary_key=True)
 
     assert isinstance(SomeModel(), CustomModelClass)
+
+
+def test_repr(db):
+    class User(db.Model):
+        name = db.Column(db.String, primary_key=True)
+
+    class Report(db.Model):
+        id = db.Column(db.Integer, primary_key=True, autoincrement=False)
+        user_name = db.Column(db.ForeignKey(User.name), primary_key=True)
+
+    db.create_all()
+
+    u = User(name='test')
+    db.session.add(u)
+    db.session.flush()
+    assert repr(u) == '<User test>'
+    assert repr(u) == str(u)
+
+    u2 = User(name=u'🐍')
+    db.session.add(u2)
+    db.session.flush()
+    assert repr(u2) == to_str(u'<User 🐍>')
+    assert repr(u2) == str(u2)
+
+    r = Report(id=2, user_name=u.name)
+    db.session.add(r)
+    db.session.flush()
+    assert repr(r) == '<Report 2, test>'
+    assert repr(u) == str(u)