CODEWITHSUNDEEP
gogo-gin
Neung Kittipong
Neung Kittipong

Reputation: 95

How to use golang create nest json array object

I try to query database and use query result to create json like these

[ {"TransID": "Transaction ID1",ProductID": ["ProID1","ProID2","ProID3","ProID4" ]},

{"TransID": "Transaction ID2","ProductID": ["ProID5","ProID6" ]} ]

so I create type struct from

type DataRecent []struct {
 TransID   string   `json:"transID"`
 ProductID []string `json:"productID"`}

and golang code is

var dataRecent DataRecent
var recent [5]string
for _, Trans := range recent {

    if Trans != "" {
        var TransID, ProductID string

        selectTrans, err := db.Query("select transaction_id, product_id from detail where transaction_id = ?", Trans)

        var arr []string
        for selectTrans.Next() {
            if err != nil {
                panic(err.Error())
            }
            errTrans := selectTrans.Scan(&TransID, &ProductID)
            if errTrans != nil {
                panic(errTrans.Error())
            }
            arr = append(arr, ProductID)
        }
    }
        dataRecent.TransID = Trans
        dataRecent.ProductID = arr

}
    c.JSON(http.StatusOK, gin.H{"status": "success", "message": "Find transactions success", "recent_trans": dataRecent})


defer db.Close()

but I can't build the code and got error

dataRecent.TransID undefined (type DataRecent has no field or method TransID) dataRecent.ProductID undefined (type DataRecent has no field or method ProductID)

I don't know what to do and stuck with these for a week. I am new programmer for golang. Help me pleae, Thank you

Upvotes: 0

Views: 228

Answers (2)

Alon
Alon

Reputation: 107

looks like dataRecent isn't initialized. I suggest you use dataRecent := DataRecent{} instead of var dataRecent DataRecent.

some other insights: I'm not sure if you've omitted the usage of make of the recent string array, or you're not aware you need to make() it. Anyway, arrays are values in Go, and if you're new to Go I strongly suggest you use slices instead. https://blog.golang.org/go-slices-usage-and-internals

Also, I'm not sure why you have to panic() in case you've found an error (in the words of Dave Cheney, panic means "game over man" - https://dave.cheney.net/tag/panic)

Upvotes: 0

Black_Dreams
Black_Dreams

Reputation: 610

Just remove the array when you create the struct

type DataRecent struct {
 TransID   string   `json:"transID"`
 ProductID []string `json:"productID"`
}

and do

var dataRecent []DataRecent

it will works for you.

Upvotes: 2

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