How to access deeply nested JSON data using Go (lang)?

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Most often developer needs to consume JSON data from other service and query over them. Querying JSON document is little time-consuming. For the last few days, I was working on a package for Golang to query JSON data easily. The idea and inspiration come from PHP-JSONQ by Nahid Bin Azhar.

Let's take a sample JSON data to start with:

{
   "name":"computers",
   "description":"List of computer products",
   "vendor":{
      "name":"Star Trek",
      "email":"info@example.com",
      "website":"www.example.com",
      "items":[
         {"id":1, "name":"MacBook Pro 13 inch retina","price":1350},
         {"id":2, "name":"MacBook Pro 15 inch retina", "price":1700},
         {"id":3, "name":"Sony VAIO", "price":1200},
         {"id":4, "name":"Fujitsu", "price":850},
         {"id":5, "name":"HP core i5", "price":850, "key": 2300},
         {"id":6, "name":"HP core i7", "price":950},
         {"id":null, "name":"HP core i3 SSD", "price":850}
      ],
      "prices":[
         2400,
         2100,
         1200,
         400.87,
         89.90,
         150.10
     ]
   }
}

Let's find a deeply nested property and handle error properly, in this case, we'll try to access name from the second element of items array, note: items is a property of vendor object. See the example below:

package main

import (
    "fmt"
    "log"

    "github.com/thedevsaddam/gojsonq"
)

func main() {
    jq := gojsonq.New().File("./sample-data.json")
    res := jq.Find("vendor.items.[1].name")

    if jq.Error() != nil {
        log.Fatal(jq.Errors())
    }

    fmt.Println(res)
}

Yahooooo! Very simple right? It looks like working with ORM of JSON data. Let's see some more example to query over the sample data.

Example 1

Query: select * from vendor.items where price > 1200 or id null

Using gojsonq we can do the query like:

package main

import (
    "fmt"

    "github.com/thedevsaddam/gojsonq"
)

func main() {
    jq := gojsonq.New().File("./sample-data.json")
    res := jq.From("vendor.items").Where("price", ">", 1200).OrWhere("id", "=", nil).Get()
    fmt.Println(res)
    // output: [map[price:1350 id:1 name:MacBook Pro 13 inch retina] map[id:2 name:MacBook Pro 15 inch retina price:1700] map[id:<nil> name:HP core i3 SSD price:850]]
}

Example 2

Query: select name, price from vendor.items where price > 1200 or id null

Using gojsonq we can do the query like:

package main

import (
    "fmt"

    "github.com/thedevsaddam/gojsonq"
)

func main() {
    jq := gojsonq.New().File("./sample-data.json")
    res := jq.From("vendor.items").Where("price", ">", 1200).OrWhere("id", "=", nil).Only("name", "price")
    fmt.Println(res)
    // output: [map[name:MacBook Pro 13 inch retina price:1350] map[name:MacBook Pro 15 inch retina price:1700] map[name:HP core i3 SSD price:850]]
}

Example 3

Query: select sum(price) from vendor.items where price > 1200 or id null

Using gojsonq we can do the query like:

package main

import (
    "fmt"

    "github.com/thedevsaddam/gojsonq"
)

func main() {
    jq := gojsonq.New().File("./sample-data.json")
    res := jq.From("vendor.items").Where("price", ">", 1200).OrWhere("id", "=", nil).Sum("price")
    fmt.Println(res)
    // output: 3900
}

Example 4

Query: select price from vendor.items where price > 1200

Using gojsonq we can do the query like:

package main

import (
    "fmt"

    "github.com/thedevsaddam/gojsonq"
)

func main() {
    jq := gojsonq.New().File("./sample-data.json")
    res := jq.From("vendor.items").Where("price", ">", 1200).Pluck("price")
    fmt.Println(res)
    // output: [1350 1700]
}

Example 5

Query: select * from vendor.items order by price

Using gojsonq we can do the query like:

package main

import (
    "fmt"

    "github.com/thedevsaddam/gojsonq"
)

func main() {
    jq := gojsonq.New().File("./sample-data.json")
    res := jq.From("vendor.items").SortBy("price").Get()
    fmt.Println(res)
    // output: [map[id:<nil> name:HP core i3 SSD price:850] map[id:4 name:Fujitsu price:850] map[id:5 name:HP core i5 price:850 key:2300] map[id:6 name:HP core i7 price:950] map[id:3 name:Sony VAIO price:1200] map[id:1 name:MacBook Pro 13 inch retina price:1350] map[id:2 name:MacBook Pro 15 inch retina price:1700]]
}

Example 6

Using gojsonq You can handle errors properly, see the code snippet below:

package main

import (
    "log"

    "github.com/thedevsaddam/gojsonq"
)

func main() {
    jq := gojsonq.New().File("./invalid-file.xjsn")
    err := jq.Error()
    if err != nil {
        log.Fatal(err)
        // 2018/06/25 00:48:58 gojsonq: open ./invalid-file.xjsn: no such file or directory
        // exit status 1
    }
}

Example 7

Let's assume we have a JSON document like this one

{
  "users":[
    {
      "id":1,
      "name":{
        "first":"John",
        "last":"Ramboo"
      }
    },
    {
      "id":2,
      "name":{
        "first":"Ethan",
        "last":"Hunt"
      }
    },
    {
      "id":3,
      "name":{
        "first":"John",
        "last":"Doe"
      }
    }
  ]
}

We want to run a query like this:

Query: select * from users where name.first=John

Using the package you can do the query easily, see the code snippet below:

package main

import (
    "fmt"

    "github.com/thedevsaddam/gojsonq"
)

func main() {
    jq := gojsonq.New().File("./data.json")
    res := jq.From("users").WhereEqual("name.first", "John").Get()
    fmt.Println(res) //output: [map[id:1 name:map[first:John last:Ramboo]] map[id:3 name:map[first:John last:Doe]]]
}

You can access nested level property using DOT (.) for methods like Where/GroupBy/SortBy etc

Note: There are some other useful methods to make life easier! If you like the package do not forget to share with your community and star the repository

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Email: okhotnikov@my.com