如何查询JSON对象

我正在使用具有以下数据结构的json文件。如何查询JSON对象

{"students":[ 
    {"Name":"Wale", "state":"Lagos", "age":20, "hobby":"dancing"}, 
    {"Name":"Ebere", "state":"Enugu", "age":18, "hobby":"eating"}, 
    {"Name":"Musa", "state":"Kano", "age":24, "hobby":"swimming"} 
]}

我与离子框架工作，需要从三个变量的所有学生说...... 状态，年龄和爱好。如果这是一个SQL语句它看起来像.... ....

$query = "Select * from students WHERE state = 'Enugu' AND age = '20' AND hobby = 'swimming'".

所以我的问题是，我怎么能做到这一点在json？

来源

2016-09-21 Lucky Agbaroji

您正在使用什么语言来从查询'json'数据？ – ode2k

因此，数据在DB中以json格式存储？ –

请更新您的文章，并回答问题@ ode2k问题，再加上一些细节。你用什么语言查询json数据？ –

如果您正在寻找自己的特殊用途语言，请查看JSONiq，专门为JSON数据模型设计的查询语言。下面是从Wikipedia采取了一个简单的例子：

for $p in collection("persons") 
where $p.age gt 20 
let $home := $p.phoneNumber[][$$.type eq "home"].number 
group by $area := substring-before($home, " ") 
return 
{ 
    "area code" : $area, 
    "count" : count($p) 
}

如果你想类似的功能，以SQL JOIN子句，看看下面的example：

let $stores := 
[ 
    { "store number" : 1, "state" : "MA" }, 
    { "store number" : 2, "state" : "MA" }, 
    { "store number" : 3, "state" : "CA" }, 
    { "store number" : 4, "state" : "CA" } 
] 
let $sales := [ 
    { "product" : "broiler", "store number" : 1, "quantity" : 20 }, 
    { "product" : "toaster", "store number" : 2, "quantity" : 100 }, 
    { "product" : "toaster", "store number" : 2, "quantity" : 50 }, 
    { "product" : "toaster", "store number" : 3, "quantity" : 50 }, 
    { "product" : "blender", "store number" : 3, "quantity" : 100 }, 
    { "product" : "blender", "store number" : 3, "quantity" : 150 }, 
    { "product" : "socks", "store number" : 1, "quantity" : 500 }, 
    { "product" : "socks", "store number" : 2, "quantity" : 10 }, 
    { "product" : "shirt", "store number" : 3, "quantity" : 10 } 
] 
let $join := 
    for $store in $stores[], $sale in $sales[] 
    where $store."store number" = $sale."store number" 
    return { 
     "nb" : $store."store number", 
     "state" : $store.state, 
     "sold" : $sale.product 
    } 
return [$join] 
-> [ 
    { "nb" : 1, "state" : "MA", "sold" : "broiler" }, 
    { "nb" : 1, "state" : "MA", "sold" : "socks" }, 
    { "nb" : 2, "state" : "MA", "sold" : "toaster" }, 
    { "nb" : 2, "state" : "MA", "sold" : "toaster" }, 
    { "nb" : 2, "state" : "MA", "sold" : "socks" }, 
    { "nb" : 3, "state" : "CA", "sold" : "toaster" }, 
    { "nb" : 3, "state" : "CA", "sold" : "blender" }, 
    { "nb" : 3, "state" : "CA", "sold" : "blender" }, 
    { "nb" : 3, "state" : "CA", "sold" : "shirt" } 
]

来源

2016-09-21 20:19:55

你可以使用.filter()为“查询”数据组。对于您所描述的特定情况下，会：

let data = {"students":[ 
 
    {"Name":"Wale", "state":"Lagos", "age":20, "hobby":"dancing"}, 
 
    {"Name":"Ebere", "state":"Enugu", "age":18, "hobby":"eating"}, 
 
    {"Name":"Musa", "state":"Kano", "age":24, "hobby":"swimming"} 
 
]}; 
 

 
// ES6!!! 
 
function filterStudents(students, name, age, state){ 
 
    return students.filter(student => student.state === state && student.age === age && student.Name === name) 
 
} 
 

 
console.log(filterStudents(data.students, 'Musa', 24, 'Kano'))

，但我会建议你用一个库，而不是手动创建过滤的情况下去。看看是否能LIB（我的创造者）会适合于你的情况：

https://github.com/DiegoZoracKy/data-query

来源

2016-09-21 20:57:57

如何查询JSON对象

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