How to increase/decrease items quantity of product in cart using REST API in magento 2?

Question

How to increase/decrease items quantity of product in cart using REST API in magento 2

• Hitesh Vaghasiya: magento.stackexchange.com/questions/163048/… call this api on one product update.
• Gagan: Using this api update product in quantity not increasing quantity of existing product, Any option to decrease product in cart

Answer 1

You can use Update cart API [updates the specified item to the specified cart.]

PUT /V1/carts/{cartId}/items/{itemId}

$body data

{
 "cartItem": {
 "itemId": 0,
 "sku": "string",
 "qty": 0,
 "name": "string",
 "price": 0,
 "productType": "string",
 "quoteId": "string",
 "productOption": {
 "extensionAttributes": {
 "customOptions": [
 {
 "optionId": "string",
 "optionValue": "string",
 "extensionAttributes": {
 "fileInfo": {
 "base64EncodedData": "string",
 "type": "string",
 "name": "string"
 }
 }
 }
 ],
 "downloadableOption": {
 "downloadableLinks": [
 0
 ]
 },
 "giftcardItemOption": {
 "giftcardAmount": 0,
 "customGiftcardAmount": 0,
 "giftcardSenderName": "string",
 "giftcardRecipientName": "string",
 "giftcardSenderEmail": "string",
 "giftcardRecipientEmail": "string",
 "giftcardMessage": "string",
 "extensionAttributes": {}
 },
 "configurableItemOptions": [
 {
 "optionId": "string",
 "optionValue": 0,
 "extensionAttributes": {}
 }
 ],
 "bundleOptions": [
 {
 "optionId": 0,
 "optionQty": 0,
 "optionSelections": [
 0
 ],
 "extensionAttributes": {}
 }
 ]
 }
 },
 "extensionAttributes": {}
 }
}