I'm working with a json file that has the following data structure.
{"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"}
]}
I'm working with the ionic framework and need to select all students from three variables say... state, age and hobby. If this was an sql statement it would look something like....
$query = "Select * from students WHERE state = 'Enugu' AND age = '20' AND hobby = 'swimming'".
So my question is, how can I do this in json?
If you are looking for a special purpose language of its own, take a look at JSONiq , a query language specifically designed for JSON data model. Here's a simple example taken from Wikipedia :
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)
}
If you want functionality similar to SQL join clause, take a look at the example below:
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" }
]
You could use .filter()
to "query" your data set. For the specific case that you described, would be:
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'))
But i would suggest you to go with a library instead of creating your filtering cases manually. See if that lib (i'm the creator) will suit to your case:
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