50 lines
1.4 KiB
Go
50 lines
1.4 KiB
Go
package utils
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import "reflect"
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// ReplaceEmptySlicesWithNil takes a pointer to any struct (or struct-like type)
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// and replaces all empty slices with nil, traversing nested fields recursively.
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func ReplaceEmptySlicesWithNil(v interface{}) {
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// Must be a pointer so we can set fields
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rv := reflect.ValueOf(v)
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if rv.Kind() != reflect.Ptr {
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panic("ReplaceEmptySlicesWithNil expects a pointer to a struct")
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}
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replaceEmptySlices(rv.Elem())
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}
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// replaceEmptySlices is the recursive helper that does the actual reflection work.
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func replaceEmptySlices(v reflect.Value) {
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switch v.Kind() {
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case reflect.Ptr:
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// If it is a pointer, recurse on the element it points to.
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if !v.IsNil() {
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replaceEmptySlices(v.Elem())
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}
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case reflect.Struct:
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// For a struct, iterate each field and process it.
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for i := 0; i < v.NumField(); i++ {
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fieldVal := v.Field(i)
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if !fieldVal.CanSet() {
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// If we can't set the field (e.g. unexported), skip it
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continue
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}
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replaceEmptySlices(fieldVal)
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}
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case reflect.Slice:
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// If it is a slice, check if it's empty; if it is, set it to nil.
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if v.Len() == 0 && v.CanSet() {
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// v.Set(reflect.Zero(v.Type())) sets slice to nil
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v.Set(reflect.Zero(v.Type()))
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} else {
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// If not empty, we should recurse on each element in case it's a struct.
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for i := 0; i < v.Len(); i++ {
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replaceEmptySlices(v.Index(i))
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}
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}
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}
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}
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