1. Load the decimal package go get github.com/shopspring/decimal
2. Structure Definition

Note: It is recommended to use json.Unmarshal(xx, &buyGoods{}) when the front-end parameter is converted into a structure containing decimal

import (
“github.com/shopspring/decimal”
)
// buy item
type buyGoods struct {
Num int json:"num" // number’,
Price decimal.Decimal json:"price" // unit price’
}

3. Logic use

// First convert int to string and then convert to decimal type for operation
sellNum, _ := decimal.NewFromString(strconv.Itoa(e.Num))
totalMoney := MulDecimal(e.Price, sellNum)

Fourth, the operation method corresponding to decimal
import "github.com/shopspring/decimal"
// Mainly used to handle floating point data precision
// addition
func AddDecimal(d1 decimal.Decimal, d2 decimal.Decimal) decimal.Decimal {
     return d1.Add(d2)
}
// subtract
func SubDecimal(d1 decimal.Decimal, d2 decimal.Decimal) decimal.Decimal {
     return d1.Sub(d2)
}
// multiply
func MulDecimal(d1 decimal.Decimal, d2 decimal.Decimal) decimal.Decimal {
     return d1.Mul(d2)
}
// division
func DivDecimal(d1 decimal.Decimal, d2 decimal.Decimal) decimal.Decimal {
     return d1.Div(d2)
}
// int
func IntDecimal(d decimal.Decimal) int64 {
     return d.IntPart()
}
// float
func FloatDecimal(d decimal.Decimal) float64 {
    f, exact := d.Float64()
    if !exact {
        return f
    }
    return 0
}