+ 不支持的操作数类型：“int”和“unicode”

Question

我正在使用模板标签从我编写的公式中返回变量。我一直在试图找出为什么我会得到这个回溯。我已经在外壳中测试了公式，并且一切正常。我在标签和视图中做了一些打印语句。但无法弄清楚这是什么原因。

追溯：

Traceback:
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/core/handlers/base.py" in get_response
  117.                             response = middleware_method(request, e)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/core/handlers/base.py" in get_response
  111.                         response = callback(request, *callback_args, **callback_kwargs)
File "/Users/urbanrunic/developement/levelend/levelend/levelend/configs/common/../../apps/common/utils/decorators.py" in wrapper
  65.                         context_instance=RequestContext(request), mimetype=mimetype)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/shortcuts/__init__.py" in render_to_response
  20.     return HttpResponse(loader.render_to_string(*args, **kwargs), **httpresponse_kwargs)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/loader.py" in render_to_string
  188.         return t.render(context_instance)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/base.py" in render
  123.             return self._render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/base.py" in _render
  117.         return self.nodelist.render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/base.py" in render
  744.                 bits.append(self.render_node(node, context))
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/debug.py" in render_node
  73.             result = node.render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/loader_tags.py" in render
  127.         return compiled_parent._render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/base.py" in _render
  117.         return self.nodelist.render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/base.py" in render
  744.                 bits.append(self.render_node(node, context))
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/debug.py" in render_node
  73.             result = node.render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/loader_tags.py" in render
  127.         return compiled_parent._render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/base.py" in _render
  117.         return self.nodelist.render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/base.py" in render
  744.                 bits.append(self.render_node(node, context))
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/debug.py" in render_node
  73.             result = node.render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django_static/templatetags/django_static.py" in render
  108.         code = self.nodelist.render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/base.py" in render
  744.                 bits.append(self.render_node(node, context))
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/debug.py" in render_node
  73.             result = node.render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/loader_tags.py" in render
  64.             result = block.nodelist.render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/base.py" in render
  744.                 bits.append(self.render_node(node, context))
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/debug.py" in render_node
  73.             result = node.render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/loader_tags.py" in render
  64.             result = block.nodelist.render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/base.py" in render
  744.                 bits.append(self.render_node(node, context))
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/debug.py" in render_node
  73.             result = node.render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/defaulttags.py" in render
  311.             return self.nodelist_true.render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/base.py" in render
  744.                 bits.append(self.render_node(node, context))
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/debug.py" in render_node
  73.             result = node.render(context)
File "/Users/urbanrunic/.virtualenvs/levelend/lib/python2.6/site-packages/django/template/defaulttags.py" in render
  227.                 nodelist.append(node.render(context))
File "/Users/urbanrunic/developement/levelend/levelend/levelend/configs/common/../../apps/lender/templatetags/lender_tags.py" in render
  15.         context[self.min] = monthlyPayment(self.how_much, self.apr_min, self.max_repayment_length)
File "/Users/urbanrunic/developement/levelend/levelend/levelend/configs/common/../../apps/lender/utils.py" in monthlyPayment
  34.     M = P / ((1 - 1 / (1 + mi) ** n) / mi)

Exception Type: TemplateSyntaxError at /results/
Exception Value: Caught TypeError while rendering: unsupported operand type(s) for +: 'int' and 'unicode'

公式：

def monthlyPayment(P, mi, n):
    """ returns monthly payment """
    M = P / ((1 - 1 / (1 + mi) ** n) / mi)
    return M

标签：

class MinMonthlyPaymentsNode(Node):
    def __init__(self, how_much, apr_min, max_repayment_length, min):
        self.how_much, self.apr_min, self.max_repayment_length, self.min = how_much, apr_min, max_repayment_length, min

    def render(self, context):
        context[self.min] = monthlyPayment(self.how_much, self.apr_min, self.max_repayment_length)
        return ''

def do_monthly_payment(parser, token):
    """
    returns a monthly payment based on the formula with interst and amount of loan

    Example usage:
    {% min_monthly_payments how_much, apr_min, max_repayment_length as [min]%}
    """
    args = token.contents.split()
    if len(args) != 6:
        raise TemplateSyntaxError, "min_monthly_payments tag takes exactly six arguments"
    if args[4] != 'as':
        raise TemplateSyntaxError, "fourth argument to the min_monthly_payments tag must be 'as'"

    return MinMonthlyPaymentsNode(args[1], args[2], args[3], args[5])

register.tag('min_monthly_payments', do_monthly_payment)

型号：

class Lender(TitleAndSlugModel):
    """
    A lender
    """

    DISBURSED_TYPES = get_namedtuple_choices('DISBURSED_TYPES', (
        (0, 'DIRECT_TO_SCHOOL', 'Directly to School'),
        (1, 'SENT_TO_YOU', 'Sent to You'),
    ))
    SUITABILITY_TYPES = get_namedtuple_choices('SUITABILITY_TYPES', (
        (0, 'UNDERGRADUATE', 'Undergraduate'),
        (1, 'GRADUATE', 'Graduate'),
        (2, 'LAW', 'Law'),
        (3, 'MEDICAL', 'Medical'),
        (4, 'PARENTS', 'Parents'),
    ))

    # Financial summary
    apr_min = models.DecimalField(max_digits=5, decimal_places=2)
    apr_max = models.DecimalField(max_digits=5, decimal_places=2)

    # Borrower rewards
    auto_debit_discount = models.DecimalField(max_digits=5, decimal_places=2)
    auto_debit_discount_note = models.CharField(max_length=250, null=True, blank=True)
    additional_rewards_1 = models.DecimalField(max_digits=5, decimal_places=2, null=True, blank=True)
    additional_rewards_1_note = models.CharField(max_length=250, null=True, blank=True)
    additional_rewards_2 = models.DecimalField(max_digits=5, decimal_places=2, null=True, blank=True)
    additional_rewards_2_note = models.CharField(max_length=250, null=True, blank=True)

    # General info
    loan_name = models.CharField(max_length=250)
    loan_services_by = models.CharField(max_length=250)
    funds_disbursed = models.PositiveIntegerField(choices=DISBURSED_TYPES.get_choices(), default=0)
    co_signer_release_available = models.IntegerField(null=True, blank=True, help_text="Please enter in months")
    suitable_for = MultiSelectField(max_length=50, choices=SUITABILITY_TYPES.get_choices())
    external_url = models.URLField(max_length=250)
    lender_logo = FileBrowseField("Image", max_length=200, directory="uploads/", extensions=[".jpg"], blank=True, null=True)
    schools = models.ManyToManyField(School)

    # Repayment
    max_repayment_length = models.IntegerField(null=True, blank=True, help_text="Please enter in years")
    max_deferral_length = models.IntegerField(null=True, blank=True, help_text="Enter as X months after graduation")

    # Rates
    interest_rate_index = models.DecimalField(max_digits=5, decimal_places=2)
    interest_rate_index_note = models.CharField(max_length=250, null=True, blank=True)
    min_repayment_rate = models.DecimalField(max_digits=5, decimal_places=2)
    min_repayment_rate_note = models.CharField(max_length=250, null=True, blank=True)
    max_repayment_rate = models.DecimalField(max_digits=5, decimal_places=2)
    max_repayment_rate_note = models.CharField(max_length=250, null=True, blank=True)

    # Fees
    origination_fee = models.DecimalField(max_digits=5, decimal_places=2, null=True, blank=True)
    guarantee_fee = models.DecimalField(max_digits=5, decimal_places=2, null=True, blank=True)

    # Notes
    notes = models.TextField(null=True, blank=True)

    def get_absolute_url(self):
        return reverse("results_detail", args=[self.slug])

    def __unicode__(self):
        return "%s" % (self.title)

再次感谢任何帮助，即使它是朝着正确方向发展的一点。谢谢！

Answer 1

回溯表明公式中的“mi”参数是 unicode 字符串，而不是数字（整数或浮点数）。我不知道 Django，但也许 token.contents.split() 正在返回一个字符串列表，你必须转换它；您可以自行检查，在您的每月付款功能中添加一些调试打印。

Answer 2

假设args 是一个字符串数组，通常情况下，您将字符串值传递到您想要数字的函数中。

return MinMonthlyPaymentsNode(args[1], args[2], args[3], args[5])

然后尝试对它们进行数学运算，但这不起作用，因为 Python 不会自动转换它们。如果所有这些参数都应该是浮点数，我会将上面的行替换为

return MinMonthlyPaymentsNode(float(args[1]), float(args[2]), float(args[3]), float(args[5]))