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Core Flatmaperr

docs/data/core-flatmaperr.md

1.53.0770 B
Original Source

Manipulates a slice and transforms and flattens it to a slice of another type using a function that can return an error. Stops iteration immediately when an error is encountered.

go
// Error case - stops on first error
result, err := lo.FlatMapErr([]int64{0, 1, 2, 3}, func(x int64, _ int) ([]string, error) {
    if x == 2 {
        return nil, fmt.Errorf("number 2 is not allowed")
    }
    return []string{strconv.FormatInt(x, 10), strconv.FormatInt(x, 10)}, nil
})
// []string(nil), error("number 2 is not allowed")
go
// Success case
result, err := lo.FlatMapErr([]int64{0, 1, 2}, func(x int64, _ int) ([]string, error) {
    return []string{strconv.FormatInt(x, 10), strconv.FormatInt(x, 10)}, nil
})
// []string{"0", "0", "1", "1", "2", "2"}, nil