How to obtain generic results using the following function?

[xiusin]

Describe the bug

I want to obtain the mapping relationship between ID and object through a function, but I am currently unable to achieve the expected result

Reproduction Steps

pub fn records_to_map[K, T](records []T, field_ string) map[K]T {
	mut result := map[K]T{}

	$for field in T.fields {
		for _, record in records {
			if field.name == field_ {
				result[record.$(field.name)] = record
			}
		}
	}
	return result
}



// test 

struct TestStruct {
pub mut:
	id i64
	name string
}

fn test_records_to_map () {
	mut records := []TestStruct{}
	records << TestStruct{
		id: 1
		name: 'aa'
	}
	records << TestStruct{
		id: 2
		name: 'bb'
	}

	records_to_map[i64, TestStruct](records, "id")
}

Expected Behavior

map[i64]TestStruct{1: {}, 2: {}}

Current Behavior

src/core/internal/fn.v:10:11: error: invalid key: expected `i64`, not `string`
    8 |         for _, record in records {
    9 |             if field.name == field_ {
   10 |                 result[record.$(field.name)] = record
      |                       ~~~~~~~~~~~~~~~~~~~~~~
   11 |             }
   12 |         }
checker summary: 1 V errors, 0 V warnings, 0 V notices

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.6 304aa9f

Environment details (OS name and version, etc.)

V full version: V 0.4.6 a1bb84f.304aa9f
OS: macos, macOS, 13.5, 22G74
Processor: 8 cpus, 64bit, little endian, Apple M2

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[felipensp]

In this case you need to check for the field type to use it as index key.

pub fn records_to_map[K, T](records []T, field_ string) map[K]T {
	mut result := map[K]T{}

	$for field in T.fields {
		for _, record in records {
			if field.name == field_ {
				$if field.typ is K {
					result[record.$(field.name)] = record
				}
			}
		}
	}
	return result
}

So

dump(records_to_map[int, TestStruct](records, "id"))
dump(records_to_map[string, TestStruct](records, "name"))

[xiusin]

@felipensp Okay, thank you. Do you need me to close this issue?