API仅返回嵌套结构的最后一行

I have built a Golang REST API. Other HTTP verbs works well except the GET that fetches everything from the database.

I have a nested struct for the model as shown below:

type Config struct {
    ID   int    `json:"id"`
    Name string `json:"name,omitempty"`
    Data *Data  `json:"data,omitempty"`
}

type Data struct {
    Host     string `json:"host,omitempty"`
    Database string `json:"database,omitempty"`
    Password string `json:"password,omitempty"`
    Username string `json:"username,omitempty"`
    Engine   string `json:"engine,omitempty"`
}

I do JSON unmarshal against the Data. See the code below:

model.go

func List(db *sql.DB, start, count int) ([]Config, error) {
    var dt string
    var c Config
    rows, err := db.Query(
        "SELECT * FROM configs LIMIT $1 OFFSET $2",
        count, start)

    if err != nil {
        return nil, err
    }

    defer rows.Close()

    configs := []Config{}

    for rows.Next() {
        //var c Config
        if err := rows.Scan(&c.ID, &c.Name, &dt); err != nil {
            return nil, err
        }
        json.Unmarshal([]byte(dt), &c.Data)
        // for _, p := range c.Data {
        //  configs = append(configs, c)
        // }
        configs = append(configs, c)
    }

    return configs, nil
}

controller.go

func (a *App) getConfigs(w http.ResponseWriter, r *http.Request) {
    count, _ := strconv.Atoi(r.FormValue("count"))
    start, _ := strconv.Atoi(r.FormValue("start"))

    if count > 10 || count < 1 {
        count = 10
    }
    if start < 0 {
        start = 0
    }

    configs, err := List(a.DB, start, count)
    fmt.Print(configs)

    if err != nil {
        fatalError(w, http.StatusInternalServerError, err.Error())
        return
    }

    jsonResponse(w, http.StatusOK, configs)
}

When I hit the get endpoint, I get the following:

[
    {
        "id": 2,
        "name": "test2",
        "data": {
            "host": "newhosty",
            "database": "locau",
            "password": "poy",
            "username": "psq",
            "engine": "dgnewy"
        }
    },
    {
        "id": 3,
        "name": "test3",
        "data": {
            "host": "newhosty",
            "database": "locau",
            "password": "poy",
            "username": "psq",
            "engine": "dgnewy"
        }
    },
    {
        "id": 4,
        "name": "test39",
        "data": {
            "host": "newhosty",
            "database": "locau",
            "password": "poy",
            "username": "psq",
            "engine": "dgnewy"
        }
    }
]

As you can see, the data part of the json is duplicated for all the id. Only name and id work as expected. I expected each data to be different as it is in the db. Looks like it only picks the last row for the data part.

Anything I'm doing wrong?

I fixed this by replacing Data *Data with Data Data. The problem was When json.Unmarshal fills c.Data it sees that there is already a struct in it and overwrites it.