lo/docs/data/core-keybyerr.md

name, slug, sourceRef, category, subCategory, signatures, variantHelpers, similarHelpers, position

name	slug	sourceRef	category	subCategory	signatures	variantHelpers	similarHelpers	position
KeyByErr	keybyerr	slice.go#L576	core	slice	func KeyByErr[K comparable, V any](collection []V, iteratee func(item V) (K, error)) (map[K]V, error)	core#slice#keybyerr	core#slice#keyby core#slice#groupby core#slice#groupbyerr core#slice#partitionby core#map#associate core#slice#keyify	231

Transforms a slice to a map using a pivot callback to compute keys. Stops iteration immediately when an error is encountered.

// Error case - stops on first error
result, err := lo.KeyByErr([]string{"a", "aa", "aaa", ""}, func(str string) (int, error) {
    if str == "" {
        return 0, fmt.Errorf("empty string not allowed")
    }
    return len(str), nil
})
// map[int]string(nil), error("empty string not allowed")

// Success case
result, err := lo.KeyByErr([]string{"a", "aa", "aaa"}, func(str string) (int, error) {
    if str == "" {
        return 0, fmt.Errorf("empty string not allowed")
    }
    return len(str), nil
})
// map[int]string{1: "a", 2: "aa", 3: "aaa"}, nil