How to Avoid Panics When Using `reflect.Value.FieldByName` on Pointer Values?

Panic from Reflect.Value.FieldByName on Pointer Value

The .FieldByName method of a reflected value can cause a panic if it is called on a pointer value. The error message "panic: reflect: call of reflect.Value.FieldByName on ptr Value" indicates that the value being passed to .FieldByName is a pointer to a struct, rather than the struct itself.

To avoid this panic, it is important to ensure that the value passed to .FieldByName is the actual struct, not a pointer to it. This can be done by using the Elem() method on the reflect.Value representing the pointer to dereference it.

Example:

<code class="go">s := reflect.ValueOf(value)
if s.Kind() == reflect.Ptr {
    s = s.Elem()
}
metric := s.FieldByName(subval.Metric).Interface()</code>

In this example, the Kind() method is used to check if the value is a pointer. If it is, the Elem() method is used to dereference the pointer and obtain the underlying struct value. This dereferenced value is then passed to .FieldByName to retrieve the field with the specified name.

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