通过python的dynamodb行数，boto查询 [英] dynamodb row count via python, boto query

问题描述

各位，我正在尝试让以下代码工作以返回表中的行数:

Folks, Am trying to get the following bit of code working to return the row count in a table:

import boto
import boto.dynamodb2
from boto.dynamodb2.table import Table
from boto.dynamodb2.fields import HashKey, RangeKey

drivers = Table('current_fhv_drivers')
rowcountquery = drivers.query(
   number = 'blah',
   expiration = 'foo',
   count=True,
  )
for x in rowcountquery:
 print x['Count']

我看到的错误是:

boto.dynamodb2.exceptions.UnknownFilterTypeError: Operator 'count' from 'count' is not recognized.

获取行数的正确语法是什么:)

Whats the correct syntaxt to get row count :)

谢谢！

推荐答案

那个异常基本上是在告诉你操作符'count'不被boto识别.

That exception is basically telling you that the operator 'count' is not recognized by boto.

如果您阅读 http://boto.readthedocs.org 上的第二段/en/latest/dynamodb2_tut.html#querying 你会看到:

If you read the second paragraph on http://boto.readthedocs.org/en/latest/dynamodb2_tut.html#querying you'll see that:

过滤器参数作为 kwargs &使用 __ 将字段名与用于过滤值的运算符分开.

Filter parameters are passed as kwargs & use a __ to separate the fieldname from the operator being used to filter the value.

所以我会将您的代码更改为:

So I would change your code to:

import boto
import boto.dynamodb2
from boto.dynamodb2.table import Table
from boto.dynamodb2.fields import HashKey, RangeKey

drivers = Table('current_fhv_drivers')
rowcountquery = drivers.query(
   number__eq = 'blah',
   expiration__eq = 'foo',
   count__eq = True,
  )
for x in rowcountquery:
 print x['Count']

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