Here’s how to create line items and attachments while creating process request:

Request type – POST

/api/1/Purchase Order/create

{
PO No: 12345,
Total Amount: 130,
Line Item:[
  {
      Description: "hose",
      Amount: 10
  },
  {
       Description: "Pipe",
       Amount: 120
  }
],
Attachment:[
   {
       Name: "Issues.xls",
       Url: "http://s3.test.com/issues.xls"
   },
   {
         Name: "Bug.xls",
         Url: "http://s3.test.com/bug.xls"
   }
]
}

Note:
Line Item,

  1. For updating a Line Item, pass the unique UUID “Id” with other parameters
  2. For deleting a Line Item, use the child table delete API (Child Table API)

Attachment:

  1. For deleting a Attachment, use attachment delete API (Attachment API)
  2. No updation for attachment
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