如何将两个JSON对象与不同顺序的相同元素进行比较？

Question

如何在python中测试两个JSON对象是否相等,忽略列表的顺序？

例如 ...

JSON文档a:

{
    "errors": [
        {"error": "invalid", "field": "email"},
        {"error": "required", "field": "name"}
    ],
    "success": false
}

JSON文件b:

{
    "success": false,
    "errors": [
        {"error": "required", "field": "name"},
        {"error": "invalid", "field": "email"}
    ]
}

a并且b应该比较相等,即使"errors"列表的顺序不同.

Answer 1

如果你想要两个具有相同元素但顺序不同的对象进行比较,那么显而易见的事情就是比较它们的排序副本 - 例如,对于由JSON字符串表示的字典a和b:

import json

a = json.loads("""
{
    "errors": [
        {"error": "invalid", "field": "email"},
        {"error": "required", "field": "name"}
    ],
    "success": false
}
""")

b = json.loads("""
{
    "success": false,
    "errors": [
        {"error": "required", "field": "name"},
        {"error": "invalid", "field": "email"}
    ]
}
""")

>>> sorted(a.items()) == sorted(b.items())
False

...但是这不起作用,因为在每种情况下,"errors"顶级字典的项目是具有不同顺序的相同元素的列表,并且sorted()不会尝试排序除"顶部"级别之外的任何内容一个可迭代的.

为了解决这个问题,我们可以定义一个ordered函数,它会递归地对它找到的任何列表进行排序(并将字典转换为(key, value)对的列表,以便它们可以订购):

def ordered(obj):
    if isinstance(obj, dict):
        return sorted((k, ordered(v)) for k, v in obj.items())
    if isinstance(obj, list):
        return sorted(ordered(x) for x in obj)
    else:
        return obj

如果我们将此函数应用于a和b,结果比较相等:

>>> ordered(a) == ordered(b)
True

Answer 2

另一种方法是使用json.dumps(X, sort_keys=True)选项:

import json
a, b = json.dumps(a, sort_keys=True), json.dumps(b, sort_keys=True)
a == b # a normal string comparison

这适用于嵌套字典和列表.

Answer 3

解码它们并将它们作为mgilson评论进行比较.

只要键和值匹配,顺序对字典无关紧要.(字典在Python中没有顺序)

>>> {'a': 1, 'b': 2} == {'b': 2, 'a': 1}
True

但是顺序在列表中很重要; 排序将解决列表的问题.

>>> [1, 2] == [2, 1]
False
>>> [1, 2] == sorted([2, 1])
True

>>> a = '{"errors": [{"error": "invalid", "field": "email"}, {"error": "required", "field": "name"}], "success": false}'
>>> b = '{"errors": [{"error": "required", "field": "name"}, {"error": "invalid", "field": "email"}], "success": false}'
>>> a, b = json.loads(a), json.loads(b)
>>> a['errors'].sort()
>>> b['errors'].sort()
>>> a == b
True

以上示例将适用于问题中的JSON.有关一般解决方案,请参阅Zero Piraeus的答案.

Answer 4

更新：请参阅https://eggachecat.github.io/jycm-json-diff-viewer/进行现场演示！现在它有一个 JS 原生实现。

隶属关系：我是该库的作者。

是的！你可以使用jycm

from jycm.helper import make_ignore_order_func
from jycm.jycm import YouchamaJsonDiffer

a = {
    "errors": [
        {"error": "invalid", "field": "email"},
        {"error": "required", "field": "name"}
    ],
    "success": False
}
b = {
    "success": False,
    "errors": [
        {"error": "required", "field": "name"},
        {"error": "invalid", "field": "email"}
    ]
}
ycm = YouchamaJsonDiffer(a, b, ignore_order_func=make_ignore_order_func([
    "^errors",
]))
ycm.diff()
assert ycm.to_dict(no_pairs=True) == {} # aka no diff

对于更复杂的示例（深层结构中的值变化）

from jycm.helper import make_ignore_order_func
from jycm.jycm import YouchamaJsonDiffer

a = {
    "errors": [
        {"error": "invalid", "field": "email"},
        {"error": "required", "field": "name"}
    ],
    "success": True
}

b = {
    "success": False,
    "errors": [
        {"error": "required", "field": "name-1"},
        {"error": "invalid", "field": "email"}
    ]
}
ycm = YouchamaJsonDiffer(a, b, ignore_order_func=make_ignore_order_func([
    "^errors",
]))
ycm.diff()
assert ycm.to_dict() == {
    'just4vis:pairs': [
        {'left': 'invalid', 'right': 'invalid', 'left_path': 'errors->[0]->error', 'right_path': 'errors->[1]->error'},
        {'left': {'error': 'invalid', 'field': 'email'}, 'right': {'error': 'invalid', 'field': 'email'},
         'left_path': 'errors->[0]', 'right_path': 'errors->[1]'},
        {'left': 'email', 'right': 'email', 'left_path': 'errors->[0]->field', 'right_path': 'errors->[1]->field'},
        {'left': {'error': 'invalid', 'field': 'email'}, 'right': {'error': 'invalid', 'field': 'email'},
         'left_path': 'errors->[0]', 'right_path': 'errors->[1]'},
        {'left': 'required', 'right': 'required', 'left_path': 'errors->[1]->error',
         'right_path': 'errors->[0]->error'},
        {'left': {'error': 'required', 'field': 'name'}, 'right': {'error': 'required', 'field': 'name-1'},
         'left_path': 'errors->[1]', 'right_path': 'errors->[0]'},
        {'left': 'name', 'right': 'name-1', 'left_path': 'errors->[1]->field', 'right_path': 'errors->[0]->field'},
        {'left': {'error': 'required', 'field': 'name'}, 'right': {'error': 'required', 'field': 'name-1'},
         'left_path': 'errors->[1]', 'right_path': 'errors->[0]'},
        {'left': {'error': 'required', 'field': 'name'}, 'right': {'error': 'required', 'field': 'name-1'},
         'left_path': 'errors->[1]', 'right_path': 'errors->[0]'}
    ],
    'value_changes': [
        {'left': 'name', 'right': 'name-1', 'left_path': 'errors->[1]->field', 'right_path': 'errors->[0]->field',
         'old': 'name', 'new': 'name-1'},
        {'left': True, 'right': False, 'left_path': 'success', 'right_path': 'success', 'old': True, 'new': False}
    ]
}

其结果可以呈现为