Django 导出导出前的导出编辑查询集

Question

我正在尝试通过模型计算待处理金额并将结果导出为 csv。但是 csv 显示一个空列，用于待处理金额

class FinancePendingResource(resources.ModelResource):
invoiceNumber = Field(attribute='invoiceNumber', column_name='Invoice Number')
student = Field(attribute='student', column_name='Student')
Schedule = Field(attribute='Schedule', column_name='Schedule')
TotalAmount = Field(attribute='TotalAmount', column_name='Total Value(PKR ₨)')
issueDate = Field(attribute='issueDate', column_name='Issue Date')
dueDate = Field(attribute='dueDate', column_name='Due Date')
amountPaid = Field(attribute='amountPaid', column_name='Amount Paid (PKR ₨)')

class Meta:
model = FinancePending
import_id_fields = ('invoiceNumber',)
fields = ('invoiceNumber', 'student', 'amountPaid', 'issueDate', 'dueDate', 'Schedule', 'TotalAmount',
'AmountPending',)
exclude = ('id',)
skip_unchanged = True
report_skipped = True
def before_export(self, queryset, *args, **kwargs):
amount_paid = FinancePending.objects.values_list('amountPaid', flat=True)
amount_paid = list(amount_paid)
total_amount = FinancePending.objects.values_list('TotalAmount', flat=True)
total_amount = list(total_amount)
# total - paid
TotalFee = [float(s.replace(',', '')) for s in total_amount]
AmountPaid = [float(s.replace(',', '')) for s in amount_paid]
def Diff(li1, li2):
return (list(set(li1) - set(li2)))
amount_pending = Diff(TotalFee, AmountPaid)
finance_pending = FinancePending()
i = 1
while i <= len(amount_pending):
FinancePending.objects.filter(invoiceNumber=i).update(AmountPending=str(amount_pending[i]))
i = i + 1
queryset.refresh_from_db()

Answer 1

假设您已经有数据来计算数据集中的amountPending，也许您不需要从数据库中读取：您可以通过处理内存中的数据集来计算数量。 这可以after_export()完成。 然后，可以将计算列添加到数据集。

也许 tablib 的动态列可以帮助添加amountPending列：

import decimal
import tablib
headers = ('invoiceNumber', 'amountPaid', 'totalAmount')
rows = [
('inv100', '100.00', "500.00"),
('inv101', '200.00', "250.00")
]
def amount_pending(row):
return decimal.Decimal(row[2]) - decimal.Decimal(row[1])
data = tablib.Dataset(*rows, headers=headers)
data.append_col(amount_pending, header="amountPending")
print(data)

这将产生以下内容：

invoiceNumber|amountPaid|totalAmount|amountPending
-------------|----------|-----------|-------------
inv100       |100.00    |500.00     |400.00       
inv101       |200.00    |250.00     |50.00