From ab23a8067c34c10d764c67b45f08347e9550176f Mon Sep 17 00:00:00 2001
From: Lance Edgar <ledgar@sacfoodcoop.com>
Date: Mon, 20 Jul 2015 12:47:37 -0500
Subject: [PATCH] Add `DecimalFieldRenderer`.

---
 tailbone/forms/renderers/__init__.py |  1 +
 tailbone/forms/renderers/common.py   | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/tailbone/forms/renderers/__init__.py b/tailbone/forms/renderers/__init__.py
index 77645e73..084933dc 100644
--- a/tailbone/forms/renderers/__init__.py
+++ b/tailbone/forms/renderers/__init__.py
@@ -27,6 +27,7 @@ FormAlchemy Field Renderers
 from tailbone.forms.renderers.common import (
     AutocompleteFieldRenderer,
     DateTimeFieldRenderer,
+    DecimalFieldRenderer,
     EnumFieldRenderer,
     YesNoFieldRenderer,
     )
diff --git a/tailbone/forms/renderers/common.py b/tailbone/forms/renderers/common.py
index bf34d9c4..1638ece1 100644
--- a/tailbone/forms/renderers/common.py
+++ b/tailbone/forms/renderers/common.py
@@ -124,6 +124,29 @@ class EnumFieldRenderer(SelectFieldRenderer):
         return SelectFieldRenderer.render(self, opts, **kwargs)
 
 
+class DecimalFieldRenderer(formalchemy.FieldRenderer):
+    """
+    Sort of generic field renderer for decimal values.  You must provide the
+    number of places after the decimal (scale).  Note that this in turn relies
+    on simple string formatting; the renderer does not attempt any mathematics
+    of its own.
+    """
+
+    def __init__(self, scale):
+        self.scale = scale
+
+    def __call__(self, field):
+        super(DecimalFieldRenderer, self).__init__(field)
+        return self
+
+    def render_readonly(self, **kwargs):
+        value = self.raw_value
+        if value is None:
+            return ''
+        fmt = '{{0:0.{0}f}}'.format(self.scale)
+        return fmt.format(value)
+
+
 class YesNoFieldRenderer(CheckBoxFieldRenderer):
 
     def render_readonly(self, **kwargs):