Question

我read the documentation，我无法弄清楚如何使用JsonPath执行子过滤器。这是一个例子......

鉴于以下JSON，如何检索地址为Sydney的人员列表？

我尝试了$.people[?(@.addresses[*].city=="Sydney")]的变体无济于事。 e.g。

$.people[?(@.addresses[*].city=="Sydney")]
$.people[?(@.addresses.city=="Sydney")]
$.people[?(@..city=="Sydney")]

JSON

{
    "people": [{
            "name": "George",
            "addresses": [{
                "city": "Sydney"
            }]
        },
        {
            "name": "Jane",
            "addresses": [{
                "city": "Brisbane"
            }]
        },
        {
            "name": "Fred",
            "addresses": [{
                    "city": "Perth"
                },
                {
                    "city": "Sydney"
                }
            ]
        }
    ]
}

首选输出

{
    "people": [{
            "name": "George",
            "addresses": [{
                "city": "Sydney"
            }]
        },
        {
            "name": "Fred",
            "addresses": [{
                    "city": "Perth"
                },
                {
                    "city": "Sydney"
                }
            ]
        }
    ]
}

我正在使用以下Java库：com.jayway.jsonpath:json-path:2.2.0

我正在使用http://jsonpath.com/在浏览器中测试我的jsonpath（也许这就是问题？）。

Answer 1

问题是@.addresses[*].city是一个集合。它不是该人的任何城市，也不是该人的唯一城市。

如果您正在寻找在悉尼拥有某些地址的人，则查询应为：

"$.people[?(\"Sydney\" in @.addresses[*].city)]"

示例：

String filter = "$.people[?(\"Sydney\" in @.addresses[*].city)]";
ReadContext ctx = JsonPath.parse(json);
List<Map<String, Object>> rez = ctx.read(filter, List.class);

如果您正在寻找悉尼所有地址的人，我不知道正确的查询。可以使用Predicate，但代码非常复杂。

仅供参考：

List<Map<String, Object>> rez = JsonPath.parse(json).read(
                "$.people[?]",
                List.class,
                new Predicate() {
            @Override
            public boolean apply(PredicateContext ctx) {
                Map<String, Object> map = ctx.item(Map.class);
                ReadContext readContext = JsonPath.parse(JSONObject.toJSONString(map));
                List<String> allAddresses = readContext.read("$.addresses[*].city");
                List<String> sydneyAddresses = readContext.read("$.addresses[?(@.city=='Sydney')].city");
                return allAddresses.size() == sydneyAddresses.size();
            }
        });

Answer 2

首先创建一个过滤器

String jsonData = "{
    "people": [{
            "name": "George",
            "addresses": [{
                "city": "Sydney"
            }]
        },
        {
            "name": "Jane",
            "addresses": [{
                "city": "Brisbane"
            }]
        },
        {
            "name": "Fred",
            "addresses": [{
                    "city": "Perth"
                },
                {
                    "city": "Sydney"
                }
            ]
        }
    ]
}"
Filter expensiveFilter = Filter.filter(Criteria.where(['people'][*]['address']['city'].eq("Sydney"));

现在您可以在JsonPath中添加它

String peoples = JsonPath.parse(jsonData).read("$['people'][?]", expensiveFilter).toString();

如何使用JsonPath执行子过滤器？

JSON

首选输出

2 个答案: