Question

在Python中，我正在尝试获取XML文件，对其进行处理，然后将数据输出到JSON。 XML处理工作正常，但我无法正确格式化JSON。输出文件看起来更像是一个包含字典的列表，这很有意义，因为这就是代码实际执行的操作。如何将其设为正确的JSON文件？

filename = 'data.json'

d = []

for elem in ET.fromstring(data).findall('.//table/row'):
        field1 = elem.get('field1')
        field2 = elem.get('field2')
        field3 = elem.get('field3')
        field4 = elem.get('field4')
        l = {'field1' : field1, 
             'field2' : field2, 
             'field3' : field3, 
             'field4' : field4}
        d.append(l)

f_out = open(filename, 'w')
json.dump(d, f_out)

f_out.close()

输出文件如下所示：

[{"field1": "field1", "field2": "field2", "field3": "field3", "field4": "field4"}, ... {"field1": "field1", "field2": "field2", "field3": "field3", "field4": "field4"}]

当我希望它看起来像：

{"field1": "field1", "field2": "field2", "field3": "field3", "field4": "field4"}, ... {"field1": "field1", "field2": "field2", "field3": "field3", "field4": "field4"}

Answer 1

根据the AWS docs，Redshift COPY命令在其输入文件中需要一系列JSON对象，并在其可选的JSONPath文件中需要一系列JSON对象。

要创建此类序列，请多次调用json.dump()：

from xml.etree import ElementTree as ET
import json


data = '''
<root><table>
  <row field1="a" field2="b" field3="c" field4="d"/>
  <row field1="1" field2="2" field3="3" field4="4"/>
</table></root>'''

filename = 'data.json'
f_out = open(filename, 'w')
for elem in ET.fromstring(data).findall('.//table/row'):
        field1 = elem.get('field1')
        field2 = elem.get('field2')
        field3 = elem.get('field3')
        field4 = elem.get('field4')
        l = {'field1' : field1,
             'field2' : field2,
             'field3' : field3,
             'field4' : field4}
        json.dump(l, f_out)
        f_out.write('\n')

f_out.close()

结果：

{"field2": "b", "field3": "c", "field1": "a", "field4": "d"}
{"field2": "2", "field3": "3", "field1": "1", "field4": "4"}

Answer 2

json.dump()有一个缩进和一个分隔符参数，如果你的json文件应该是人类可读的，你可能想要提供它。

示例：

json.dump({'1': 2, '3': 4}, f_out, indent=4, separators=(',', ': '))

结果：

{
    "1": 2,
    "3": 4
}

请参阅https://docs.python.org/2/library/json.html#basic-usage

将JSON写入文件 - 格式错误？

2 个答案: