How to get all metafields despite if they have a value or not using Rest API

[TestT1232]

I am trying to retrieve all metafields when the OwnerResource is set to 'Product', but the API only returns metafields that have a value. Metafields without a value are not included in the response.

Example:

Product 1:

• metafield1 = 4
• metafield2

Using the REST API, only metafield1 is returned. Metafield2 is not returned in response because it does not have a value.

Can you have a look at this?

[Ahsan-ah-med]

Can you explain where you use fetch API 

[TestT1232]

I am using endpoints from shopify official documentation below.

Metafield (shopify.dev) 

[Ahsan-ah-med]

This is an admin API, and my question is: where do you use these endpoints, on the admin App or the storefront?