34、高端织物基食品安全系统案例研究

高端织物基食品安全系统案例研究

1. 食品相关功能实现

1.1 食品配料流通

该功能实现了用户（即配料卖家）之间的配料流通，并将变更记录保存到区块链。以下是具体的代码实现：

// Change in ingredients
func (c *IngredientsExchangeCC) ingredientExchange(stub shim.ChaincodeStubInterface, args []string) pb.Response {
    // Check the number of parameters
    if len(args) != 3 {
        return shim.Error("not enough args")
    }
    // Verify the correctness of the parameters
    ownerId := args[0]
    ingredientId := args[1]
    currentOwnerId := args[2]
    if ownerId == "" || ingredientId == "" || currentOwnerId == "" {
        return shim.Error("invalid args")
    }
    // Verify the existence of the data
    originOwnerBytes, err := stub.GetState(constructUserKey(ownerId))
    if err != nil || len(ori