yanunon yanunon - 4 months ago 30
JSON Question

How to decode JSON with type convert from string to float64 in Golang?

I need to decode a JSON string with the float number like:

{"name":"Galaxy Nexus", "price":"3460.00"}


I use the Golang code below:

package main

import (
"encoding/json"
"fmt"
)

type Product struct {
Name string
Price float64
}

func main() {
s := `{"name":"Galaxy Nexus", "price":"3460.00"}`
var pro Product
err := json.Unmarshal([]byte(s), &pro)
if err == nil {
fmt.Printf("%+v\n", pro)
} else {
fmt.Println(err)
fmt.Printf("%+v\n", pro)
}
}


When I run it, get the result:

json: cannot unmarshal string into Go value of type float64
{Name:Galaxy Nexus Price:0}


I want to know how to decode the JSON string with type convert.

Answer

The answer is considerably less complicated. Just add tell the JSON interpeter it's a string encoded float64 with ,string (note that I only changed the Price definition):

package main

import (
    "encoding/json"
    "fmt"
)

type Product struct {
    Name  string
    Price float64 `json:",string"`
}

func main() {
    s := `{"name":"Galaxy Nexus", "price":"3460.00"}`
    var pro Product
    err := json.Unmarshal([]byte(s), &pro)
    if err == nil {
        fmt.Printf("%+v\n", pro)
    } else {
        fmt.Println(err)
        fmt.Printf("%+v\n", pro)
    }
}
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