How to Avoid \'reflect: Call with too few input arguments\' Error When Using .Call in Go?

Proper Utilization of Reflect Package's .Call Method

In working with the reflect package's .Call function, developers often encounter the error "reflect: Call with too few input arguments." This issue stems from the need to populate the "in" parameter with the appropriate value representing the function's input.

Constructing the "in" Argument

To resolve this issue, the "in" argument must be a slice of reflect.Value objects, where each value represents the expected type of the corresponding function parameter. In the provided example, the method requires a single parameter of type map[string][]string.

To create the slice containing the input parameter, the correct approach is to use:

<code class="go">in := []reflect.Value{reflect.ValueOf(params)}</code>

where "params" is the map you wish to pass to the function.

Example Usage

For the example method:

<code class="go">func (c *Controller) Root(params map[string][]string) map[string] string{}</code>

The correct call using .Call would be:

<code class="go">params := map[string][]string{"foo": []string{"bar"}}
in := []reflect.Value{reflect.ValueOf(params)}
return_values := reflect.ValueOf(&controller_ref).MethodByName(action_name).Call(in)</code>

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