templatetags: manage decimals on mathematics filters (#41868)

combo/public/templatetags/combo.py

@@ -18,6 +18,8 @@ from __future__ import absolute_import
 
 import datetime
 from decimal import Decimal
+from decimal import InvalidOperation as DecimalInvalidOperation
+from decimal import DivisionByZero as DecimalDivisionByZero
 import json
 import time
 
@@ -441,20 +443,55 @@ def age_in_months(value, today=None):
         return ''
     return years * 12 + months
 
+def parse_decimal(value, default=Decimal(0)):
+    if isinstance(value, six.string_types):
+        # replace , by . for French users comfort
+        value = value.replace(',', '.')
+    try:
+        return Decimal(value).quantize(Decimal('1.0000')).normalize()
+    except (ArithmeticError, TypeError):
+        return default
+
 @register.filter(is_safe=False)
 def decimal(value, arg=None):
     if not isinstance(value, Decimal):
-        if isinstance(value, six.string_types):
-            # replace , by . for French users comfort
-            value = value.replace(',', '.')
-        try:
-            value = Decimal(value).quantize(Decimal('1.0000')).normalize()
-        except (ArithmeticError, TypeError):
-            value = Decimal(0)
+        value = parse_decimal(value)
     if arg is None:
         return value
     return defaultfilters.floatformat(value, arg=arg)
 
+@register.filter
+def add(term1, term2):
+    '''replace the "add" native django filter'''
+
+    term1_decimal = parse_decimal(term1, default=None)
+    term2_decimal = parse_decimal(term2, default=None)
+
+    if term1_decimal is not None and term2_decimal is not None:
+        return term1_decimal + term2_decimal
+    if not term1 and term2_decimal is not None:
+        return term2_decimal
+    if not term2 and term1_decimal is not None:
+        return term1_decimal
+    return defaultfilters.add(term1, term2)
+
+@register.filter
+def subtract(term1, term2):
+    return parse_decimal(term1) - parse_decimal(term2)
+
+@register.filter
+def multiply(term1, term2):
+    return parse_decimal(term1) * parse_decimal(term2)
+
+@register.filter
+def divide(term1, term2):
+    try:
+        return parse_decimal(term1) / parse_decimal(term2)
+    except DecimalInvalidOperation:
+        return ''
+    except DecimalDivisionByZero:
+        return ''
+
 
 _json_script_escapes = {
     ord('>'): '\\u003E',

tests/test_public_templatetags.py

@@ -544,6 +544,86 @@ def test_decimal_templatetag():
     assert tmpl.render(Context()) == 'hello'
 
 
+def test_mathematics_templatetag():
+    tmpl = Template('{{ term1|add:term2 }}')
+
+    # using strings
+    assert tmpl.render(Context({'term1': '1.1', 'term2': 0})) == '1.1'
+    assert tmpl.render(Context({'term1': 'not a number', 'term2': 1.2})) == ''
+    assert tmpl.render(Context({'term1': 0.3, 'term2': "1"})) == '1.3'
+    assert tmpl.render(Context({'term1': 1.4, 'term2': "not a number"})) == ''
+
+    # add
+    assert tmpl.render(Context({'term1': 4, 'term2': -0.9})) == '3.1'
+    assert tmpl.render(Context({'term1': '4', 'term2': -0.8})) == '3.2'
+    assert tmpl.render(Context({'term1': 4, 'term2': '-0.7'})) == '3.3'
+    assert tmpl.render(Context({'term1': '4', 'term2': '-0.6'})) == '3.4'
+    assert tmpl.render(Context({'term1': '', 'term2': 3.5})) == '3.5'
+    assert tmpl.render(Context({'term1': None, 'term2': 3.5})) == '3.5'
+    assert tmpl.render(Context({'term1': 3.6, 'term2': ''})) == '3.6'
+    assert tmpl.render(Context({'term1': '', 'term2': ''})) == ''
+    assert tmpl.render(Context({'term1': 3.6, 'term2': None})) == '3.6'
+    assert tmpl.render(Context({'term1': 0, 'term2': ''})) == '0'
+    assert tmpl.render(Context({'term1': '', 'term2': 0})) == '0'
+    assert tmpl.render(Context({'term1': 0, 'term2': 0})) == '0'
+
+    # add using ',' instead of '.' decimal separator
+    assert tmpl.render(Context({'term1': '1,1', 'term2': '2,2'})) == '3.3'
+    assert tmpl.render(Context({'term1': '1,1', 'term2': '2.2'})) == '3.3'
+    assert tmpl.render(Context({'term1': '1,1', 'term2': 2.2})) == '3.3'
+    assert tmpl.render(Context({'term1': '1,1', 'term2': 0})) == '1.1'
+    assert tmpl.render(Context({'term1': '1,1', 'term2': ''})) == '1.1'
+    assert tmpl.render(Context({'term1': '1,1', 'term2': None})) == '1.1'
+    assert tmpl.render(Context({'term1': '1.1', 'term2': '2,2'})) == '3.3'
+    assert tmpl.render(Context({'term1': 1.1, 'term2': '2,2'})) == '3.3'
+    assert tmpl.render(Context({'term1': 0, 'term2': '2,2'})) == '2.2'
+    assert tmpl.render(Context({'term1': '', 'term2': '2,2'})) == '2.2'
+    assert tmpl.render(Context({'term1': None, 'term2': '2,2'})) == '2.2'
+
+    # subtract
+    tmpl = Template('{{ term1|subtract:term2 }}')
+    assert tmpl.render(Context({'term1': 5.1, 'term2': 1})) == '4.1'
+    assert tmpl.render(Context({'term1': '5.2', 'term2': 1})) == '4.2'
+    assert tmpl.render(Context({'term1': 5.3, 'term2': '1'})) == '4.3'
+    assert tmpl.render(Context({'term1': '5.4', 'term2': '1'})) == '4.4'
+    assert tmpl.render(Context({'term1': '', 'term2': -4.5})) == '4.5'
+    assert tmpl.render(Context({'term1': 4.6, 'term2': ''})) == '4.6'
+    assert tmpl.render(Context({'term1': '', 'term2': ''})) == '0'
+    assert tmpl.render(Context({'term1': 0, 'term2': ''})) == '0'
+    assert tmpl.render(Context({'term1': '', 'term2': 0})) == '0'
+    assert tmpl.render(Context({'term1': 0, 'term2': 0})) == '0'
+
+    # multiply
+    tmpl = Template('{{ term1|multiply:term2 }}')
+    assert tmpl.render(Context({'term1': '3', 'term2': '2'})) == '6'
+    assert tmpl.render(Context({'term1': 2.5, 'term2': 2})) == '5.0'
+    assert tmpl.render(Context({'term1': '2.5', 'term2': 2})) == '5.0'
+    assert tmpl.render(Context({'term1': 2.5, 'term2': '2'})) == '5.0'
+    assert tmpl.render(Context({'term1': '2.5', 'term2': '2'})) == '5.0'
+    assert tmpl.render(Context({'term1': '', 'term2': '2'})) == '0'
+    assert tmpl.render(Context({'term1': 2.5, 'term2': ''})) == '0.0'
+    assert tmpl.render(Context({'term1': '', 'term2': ''})) == '0'
+    assert tmpl.render(Context({'term1': 0, 'term2': ''})) == '0'
+    assert tmpl.render(Context({'term1': '', 'term2': 0})) == '0'
+    assert tmpl.render(Context({'term1': 0, 'term2': 0})) == '0'
+
+    # divide
+    tmpl = Template('{{ term1|divide:term2 }}')
+    assert tmpl.render(Context({'term1': 16, 'term2': 2})) == '8'
+    assert tmpl.render(Context({'term1': 6, 'term2': 0.75})) == '8'
+    assert tmpl.render(Context({'term1': '6', 'term2': 0.75})) == '8'
+    assert tmpl.render(Context({'term1': 6, 'term2': '0.75'})) == '8'
+    assert tmpl.render(Context({'term1': '6', 'term2': '0.75'})) == '8'
+    assert tmpl.render(Context({'term1': '', 'term2': '2'})) == '0'
+    assert tmpl.render(Context({'term1': 6, 'term2': ''})) == ''
+    assert tmpl.render(Context({'term1': '', 'term2': ''})) == ''
+    assert tmpl.render(Context({'term1': 0, 'term2': ''})) == ''
+    assert tmpl.render(Context({'term1': '', 'term2': 0})) == ''
+    assert tmpl.render(Context({'term1': 0, 'term2': 0})) == ''
+    tmpl = Template('{{ term1|divide:term2|decimal:2 }}')
+    assert tmpl.render(Context({'term1': 2, 'term2': 3})) == '0.67'
+
+
 def test_json_script():
     tmpl = Template('{{ plop|json_script:"toto" }}')
     assert tmpl.render(Context({'plop': {'a': 'b'}})) == '<script id="toto" type="application/json">{"a": "b"}</script>'