jsqr

Query or evaluate JSON values.

Install

go get github.com/ofabricio/jsqr

Example

(Playground)

package main

import "github.com/ofabricio/jsqr"

func main() {

    j := []byte(`
        {
            "data": { "store": "Grocery" },
            "tags": [
                { "name": "Fruit", "items": [{ "name": "Apple" }] },
                { "name": "Snack", "items": [{ "name": "Chips" }] },
                { "name": "Drink", "items": [{ "name": "Water" }, { "name": "Wine" }] }
            ]
        }
    `)

    a := jsqr.Get(j, `.data.store`)
    b := jsqr.Get(j, `.tags.[1].name == "Snack"`)
    c := jsqr.Get(j, `.tags.[ .name == "Drink" ].items.[0].name.(upper)`)

    fmt.Println(a) // "Grocery"
    fmt.Println(b) // true
    fmt.Println(c) // "WATER"
}

Also works with Go types:

(Playground)

package main

import "github.com/ofabricio/jsqr"

func main() {

    s := Store{
        Data: Data{
            Name: "Grocery",
        },
        Tags: []Tags{
            {Name: "Fruit", Items: []Item{{Name: "Apple"}}},
            {Name: "Snack", Items: []Item{{Name: "Chips"}}},
            {Name: "Drink", Items: []Item{{Name: "Water"}, {Name: "Wine"}}},
        },
    }

    a := jsqr.GetStruct(s, `.Data.Name`)
    b := jsqr.GetStruct(s, `.Tags.[1].Name == "Snack"`)
    c := jsqr.GetStruct(s, `.Tags.[ .Name == "Drink" ].Items.[0].Name.(upper)`)

    fmt.Println(a) // "Grocery"
    fmt.Println(b) // true
    fmt.Println(c) // "WATER"
}

Note that jsqr.Get*(v, expr) compiles the expression each time it is called. Avoid it with jsqr.Compile(expr).

Documentation

Expression	Description
.	Returns the current context.
.a	Returns a key value. For keys with characters other than [a-zA-Z0-9_] use ."a".
.a == 100	Boolean expression that returns either true or false.
.[0]	Returns the array item at the index.
.[ .a > .b ]	Returns the array item that matches the filter expression.
== != >= > <= <	Comparison operators.
eq ne	Case insensitive comparison operators.
& |	Logical operators: .a == .b & .c == 100 | .d == true.
.(func)	Calls a function. See below.

Functions

Function	Description
upper	Converts a string to uppercase.
lower	Converts a string to lowercase.
exists	Tells if a context exists.