From 0a0ff7a0eca33fe414d61d23cb175d1ee8488dec Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=89loi=20Rivard?= <eloi.rivard@aquilenet.fr>
Date: Fri, 24 Apr 2020 12:35:45 +0200
Subject: [PATCH] Implemented MonthField

---
 CHANGES.rst                 |  7 +++++++
 docs/fields.rst             |  2 ++
 src/wtforms/fields/core.py  | 11 +++++++++++
 src/wtforms/fields/html5.py |  8 ++++++++
 tests/test_fields.py        | 24 ++++++++++++++++++++++++
 5 files changed, 52 insertions(+)

diff --git a/CHANGES.rst b/CHANGES.rst
index 5d2fff998..f7eefc420 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,5 +1,12 @@
 .. currentmodule:: wtforms
 
+Version 2.x.x
+-------------
+
+Unreleased
+
+-   Implemented :class:`~wtforms.fields.core.MonthField`. :pr:`530` :pr:`593`
+
 
 Version 3.0.0
 -------------
diff --git a/docs/fields.rst b/docs/fields.rst
index c7e3da7fa..86d30c767 100644
--- a/docs/fields.rst
+++ b/docs/fields.rst
@@ -582,6 +582,8 @@ namespace and can be overridden or modified just like any other widget.
 
 .. autoclass:: DateField(default field arguments, format='%Y-%m-%d')
 
+.. autoclass:: MonthField(default field arguments, format='%Y-%m')
+
 .. autoclass:: TimeField(default field arguments, format='%H:%M')
 
 .. autoclass:: DateTimeLocalField(default field arguments, format='%Y-%m-%d %H:%M:%S')
diff --git a/src/wtforms/fields/core.py b/src/wtforms/fields/core.py
index 9c4b46a87..a0ce0e062 100644
--- a/src/wtforms/fields/core.py
+++ b/src/wtforms/fields/core.py
@@ -26,6 +26,7 @@
     "SelectMultipleField",
     "StringField",
     "TimeField",
+    "MonthField",
 )
 
 
@@ -889,6 +890,16 @@ def process_formdata(self, valuelist):
                 raise ValueError(self.gettext("Not a valid time value"))
 
 
+class MonthField(DateField):
+    """
+    Same as DateField, except represents a month, stores a `datetime.date`
+    with `day = 1`.
+    """
+
+    def __init__(self, label=None, validators=None, format="%Y-%m", **kwargs):
+        super().__init__(label, validators, format, **kwargs)
+
+
 class FormField(Field):
     """
     Encapsulate a form as a field in another form.
diff --git a/src/wtforms/fields/html5.py b/src/wtforms/fields/html5.py
index 177001fd8..26d7efac6 100644
--- a/src/wtforms/fields/html5.py
+++ b/src/wtforms/fields/html5.py
@@ -73,6 +73,14 @@ class TimeField(core.TimeField):
     widget = widgets.TimeInput()
 
 
+class MonthField(core.MonthField):
+    """
+    Represents an ``<input type="month">``.
+    """
+
+    widget = widgets.MonthInput()
+
+
 class DateTimeLocalField(core.DateTimeField):
     """
     Represents an ``<input type="datetime-local">``.
diff --git a/tests/test_fields.py b/tests/test_fields.py
index 5cf7cd5f2..f62324edd 100644
--- a/tests/test_fields.py
+++ b/tests/test_fields.py
@@ -28,6 +28,7 @@
 from wtforms.fields import IntegerField
 from wtforms.fields import IntegerRangeField
 from wtforms.fields import Label
+from wtforms.fields import MonthField
 from wtforms.fields import MultipleFileField
 from wtforms.fields import PasswordField
 from wtforms.fields import RadioField
@@ -756,6 +757,29 @@ def test_failure(self):
         assert form.a.process_errors[0] == "Not a valid date value"
 
 
+class TestMonthField:
+    class F(Form):
+        a = MonthField()
+        b = MonthField(format="%m/%Y")
+
+    def test_basic(self):
+        d = date(2008, 5, 1)
+        form = self.F(DummyPostData(a=["2008-05"], b=["05/2008"]))
+
+        assert d == form.a.data
+        assert "2008-05" == form.a._value()
+
+        assert d == form.b.data
+
+    def test_failure(self):
+        form = self.F(DummyPostData(a=["2008-bb"]))
+
+        assert not form.validate()
+        assert 1 == len(form.a.process_errors)
+        assert 1 == len(form.a.errors)
+        assert "Not a valid date value" == form.a.process_errors[0]
+
+
 class TestTimeField:
     class F(Form):
         a = TimeField()