db.Query with sql join error Scan error on column

Question

error!!!

Scan error on column index 1, name "url": unsupported Scan, storing driver.Value type []uint8 into type *[]handle.Movie

https://gyazo.com/7532a1c3793c892e721054998865609d

https://gyazo.com/278066e6da16f13cd9c56874beb71026

type Movie struct {
    ID         int
    Url        string
    CategoryID uint
}

type Category struct {
    ID     int
    Name   string
    Movies []Movie
}


func Connected() []Category { 
    db := ConnectDB()
    defer db.Close()

    //sql
    query := `SELECT c.name,m.url FROM categories c left join movies m on c.id = m.category_id`

    rows, err := db.Query(query)
    if err != nil {
        log.Fatal(err)
    }

    var sli []Category
    var v1 Category   
    for rows.Next() {

        if err := rows.Scan(&v1.Name, &v1.Movies); err != nil {
            log.Fatal(err)
        }

        sli = append(sli, v1)
    }
    fmt.Println(sli[0].Movies)
    return sli
}

I want to achieve this result!!!

[{1 aaa [https//you...,https//you...],2 bbb [https/you...]}]

I want to get a movie that is linked by category association by slice

-----------------------------PS ---------------------------------

This is what I wanted to do!!!

func Connected() []Category {
    db := ConnectDB()
    defer db.Close()

    //sql
    query := `SELECT c.id, c.name, m.id, m.url FROM categories c left join movies m on c.id = m.category_id ORDER BY c.id ASC`
    rows, err := db.Query(query)
    if err != nil {
        log.Fatal(err)
    }

    var sli []Category
    var c Category 

    var m Movie

    for rows.Next() {
        if err := rows.Scan(&c.ID, &c.Name, &m.ID, &m.Url); err != nil {

            log.Fatal(err)
        }
        m.CategoryID = c.ID
        l := len(sli)
        if l > 0 && sli[l-1].ID == c.ID {
            sli[l-1].Movies = append(sli[l-1].Movies, m)

        } else {
            if len(c.Movies) != 0 {
                c.Movies = remove(c.Movies, c.Movies[0])
            }

            c.Movies = append(c.Movies, m)
            sli = append(sli, c) 


        }
    }
    return sli
}



func remove(ints []Movie, search Movie) []Movie {
    result := []Movie{}
    for _, v := range ints {
        if v != search {
            result = append(result, v)
        }
    }
    return result
}

Thanks everyone

Answer 1

well as I see you are trying to store a single URL into an array of Movie struct which is impossible. your query may return all URLs for each category but each URL is in a single row and you should aggregate them your self. and as I know you should scan data into Golang default types, not your custom structs. mapping your data into your custom struct is a different thing.

this is a sample code but I don't have access to your database so I can't test it but it should work as you want.

type Movie struct {
ID         int
Url        string
CategoryID uint
}

type Category struct {
ID     int
Name   string
Movies []Movie
}


func Connected() []Category { 
db := ConnectDB()
defer db.Close()

//sql
query := `SELECT c.id, c.name, m.id, m.url FROM categories c left join movies m on c.id = m.category_id 
ORDER BY c.id ASC`

rows, err := db.Query(query)
if err != nil {
    log.Fatal(err)
}

var sli []Category
var v1 Category
var m Movie
for rows.Next() {
    if err := rows.Scan(&v1.ID, &v1.Name, &m.ID, &m.Url); err != nil {
        log.Fatal(err)
    }
    m.CategoryID = v1.ID
    l := len(sli)
    if l > 0 && sli[l - 1].ID == v1.ID {
        sli[l - 1].Movies = append(sli[l - 1].Movies, m)
    } else {
        v1.Movies = append(v1.Movies, m)
        sli = append(sli, v1)
    }
}
fmt.Println(sli[0].Movies)
return sli
}