JavaScript - 循环 JSON 数组并匹配子数组中的字符串答案

【问题标题】：JavaScript - Loop JSON array and match string in subarrayJavaScript - 循环 JSON 数组并匹配子数组中的字符串
【发布时间】：2015-04-05 09:48:42
【问题描述】：

我有带有子数组的 JSON 数组，我想循环它并查找用户的用户名是否为例如“admin”。如果是这样，则创建 JSON 数组包含属于用户“管理员”（地区、运动、城市等）的数据。我不知道如何在循环中找到它然后对其进行切片。对于愚蠢的问题，我很抱歉，但我有点迷茫。

这是具有我所拥有的结构的 JSON 数组：

[
    {
        "_id": "5520f52e2c0a22541541bde1",
        "region": {
            "_id": "551e6779d8f1afa01bd86529",
            "name": "region_name"
        },
        "user": {
            "_id": "551a938af056a7fc099879c1",
            "firstName": "John",
            "lastName": "Boo",
            "username": "admin",
            "id": "551a938af056a7fc099879c1"
        },
        "__v": 0,
        "sport": [
            {
                "_id": "551e69c6d8f1afa01bd86533",
                "name": "Running"
            }
        ],
        "city": "some_city",
        "advert": "some_advert",
        "title": "I want to run!",
        "created": "2015-04-05T08:41:18.173Z"
    },
    {
        "_id": "552010740628cab002b3a700",
        "region": {
            "_id": "551e67b6d8f1afa01bd8652f",
            "name": "region_name"
        },
        "user": {
            "_id": "551a938af056a7fc099879c1",
            "firstName": "Bill",
            "lastName": "Foo",
            "username": "bill_foo",
            "id": "551a938af056a7fc099879c1"
        },
        "__v": 0,
        "sport": [
            {
                "_id": "551e5e01abb74a8423410b88",
                "nazev": "Hockey"
            }
        ],
        "city": "some_city",
        "advert": "some_advert",
        "title": "some_title",
        "created": "2015-04-04T16:25:24.733Z"
    }
]

编辑：用户 'admin' 的预期结果是：

[
    {
        "_id": "5520f52e2c0a22541541bde1",
        "region": {
            "_id": "551e6779d8f1afa01bd86529",
            "name": "region_name"
        },
        "user": {
            "_id": "551a938af056a7fc099879c1",
            "firstName": "John",
            "lastName": "Boo",
            "username": "admin",
            "id": "551a938af056a7fc099879c1"
        },
        "__v": 0,
        "sport": [
            {
                "_id": "551e69c6d8f1afa01bd86533",
                "name": "Running"
            }
        ],
        "city": "some_city",
        "advert": "some_advert",
        "title": "I want to run!",
        "created": "2015-04-05T08:41:18.173Z"
}]

【问题讨论】：

请包括预期的输出。
显示你尝试过的一些代码
使用 jquery .each 等：[使用 $.each 对 Json 数据进行 jquery 循环][1] [1]：stackoverflow.com/questions/2342371/…
如果您的数据确实是 JSON，那么您需要首先使用 JSON.parse，因为 [...]JSON is a 100% textual data interchange format originally inspired by JavaScript objects[...]，但不是允许您直接访问任何元素的数据结构。否则，您可以使用Matt Ellen 的答案中的 for 循环。

标签： javascript json loops arrays

【解决方案1】：

遍历数组，取出用户名为admin的用户的每一项：

var result = [];
var nameToSearchFor = 'admin';

for(var index = 0; index < arr.length; index++)
{
    var item = arr[index];
    if(item.user.username === nameToSearchFor)
    {
        result.push(item);
    }
}

【讨论】：

【解决方案2】：

您的问题的一个解决方案是搜索驻留在admin 用户名的索引。在您的情况下，位于提供的 json 数组的 0 索引处。所以你可以通过索引获取整个对象，像这样：

var i = 0;
for(; i< json.length; i++){
  if(json[i].user.username === "admin") break;
}

现在您可以使用admin 数据获取对象。像这样：

json[i].user.firstName

检查这个垃圾here

编辑如果您只想将该切片放入一个新数组中，那么您可以直接切片该 json 数组，因为您已经有了索引。

var newArray = json.slice(i, i+1);

【讨论】：

【解决方案3】：

您可以使用像 jinqJs 这样的开源项目对数组执行类似 SQL 的查询。

var data = [
    {
        "_id": "5520f52e2c0a22541541bde1",
        "region": {
            "_id": "551e6779d8f1afa01bd86529",
            "name": "region_name"
        },
        "user": {
            "_id": "551a938af056a7fc099879c1",
            "firstName": "John",
            "lastName": "Boo",
            "username": "admin",
            "id": "551a938af056a7fc099879c1"
        },
        "__v": 0,
        "sport": [
            {
                "_id": "551e69c6d8f1afa01bd86533",
                "name": "Running"
            }
        ],
        "city": "some_city",
        "advert": "some_advert",
        "title": "I want to run!",
        "created": "2015-04-05T08:41:18.173Z"
    },
    {
        "_id": "552010740628cab002b3a700",
        "region": {
            "_id": "551e67b6d8f1afa01bd8652f",
            "name": "region_name"
        },
        "user": {
            "_id": "551a938af056a7fc099879c1",
            "firstName": "Bill",
            "lastName": "Foo",
            "username": "bill_foo",
            "id": "551a938af056a7fc099879c1"
        },
        "__v": 0,
        "sport": [
            {
                "_id": "551e5e01abb74a8423410b88",
                "nazev": "Hockey"
            }
        ],
        "city": "some_city",
        "advert": "some_advert",
        "title": "some_title",
        "created": "2015-04-04T16:25:24.733Z"
    }
];

var result = jinqJs()
                .from(data)
                .where(function(row){return row.user.username==='admin';})
                .select();

document.body.innerHTML = '<pre>' + JSON.stringify(result, null, 4) + '</pre><br><br>';

&lt;script src="https://rawgit.com/fordth/jinqJs/master/jinqjs.js"&gt;&lt;/script&gt;

【讨论】：