Core Mapentrieserr - Lo

Transforms both keys and values using an predicate function. Returns an error if the iteratee function fails, stopping iteration immediately.

in := map[string]int{"foo": 1, "bar": 2, "baz": 3}
out, err := lo.MapEntriesErr(in, func(k string, v int) (int, string, error) {
    if k == "bar" {
        return 0, "", fmt.Errorf("bar not allowed")
    }
    return v, k, nil
})
// map[int]string(nil), error("bar not allowed")

in := map[string]int{"foo": 1, "bar": 2}
out, err := lo.MapEntriesErr(in, func(k string, v int) (int, string, error) {
    return v, k, nil
})
// map[int]string{1:"foo", 2:"bar"}, nil