title: upload a file(.pdf, .jpg etc) using rails active storage via API through postman? (not through rails views)
body: <p>I saw <strong>N</strong> number of tutorials on uploading a file to active storage locally, to S3 etc using <strong>rails view</strong>. But I cannot find a legit source on how to upload a file to an active storage through API Say via postman, like what are prerequisites required to pass an attachment through API via postman?</p>
  
  <p>Let me detail it.</p>
  
  <p><em>Step 1:</em> Through React or any frontend framework, I will choose a file to upload(a .PDF file), ultimately it should be saved somewhere.</p>
  
  <p><em>Step 2:</em> This chosen file should be passed through as API to the backend service where the storage of the chosen file to be saved in a storage like AWS S3.</p>
  
  <p>How will the API request be sent to store the file? Can someone help me out with it?</p>