将值附加到切片的切片

Question

consider this piece of code:

func main() {
    items := func1()

    for _, v := range items {
        v.Status = append(v.Status, false)
    }

    fmt.Println(items)

}

//TestCaseItem represents the test case
type TestCaseItem struct {
    Actual   []string
    Expected []string
    Status   []bool
}

func func1() []TestCaseItem {
    var tc = make([]TestCaseItem, 0)

    var item = &TestCaseItem{}
    item.Actual = append(item.Actual, "test1")
    item.Actual = append(item.Actual, "test2")

    tc = append(tc, *item)

    return tc
}

i have an slice of type TestCaseItem struct. In that struct i have slice of string and bool properties. first i call func1 function to grab some data and then iterate over that slice and try to append more data insdide, but the output of this code is [{[test1 test2] [] []}] where are the booleans ?

i feel like the problem is []TestCaseItem cuz its a slice that holds values rather than pointers and maybe i'll miss sth. can anybody explain this?

Answer 1

You're appending the bool values to copies of your TestCaseItems.

You either need to use a pointer to the items:

func func1() []*TestCaseItem {
    var tc = make([]*TestCaseItem, 0)

    var item = &TestCaseItem{}
    item.Actual = append(item.Actual, "test1")
    item.Actual = append(item.Actual, "test2")

    tc = append(tc, item)

    return tc
}

Or you need to append to the Status field of the TestCaseItem value that's in the slice.

for i := range items {
    items[i].Status = append(items[i].Status, false)
}