Cart mutation response error

[AlexanderWeb]

I have the following UI where I want to increment o decrement the quantity of a product and update the cart immediately.

I am using the following mutation:

...
const handleUpdateExistingCartLines =() =>

...

const updateCartMutation = gql`
${CART_COMMON_FIELDS}
mutation cartLinesUpdate($cartId: ID!, $lines: [CartLineInput!]!) {
cartLinesUpdate(cartId: $cartId, lines: $lines) {
cart {
...cartProducts
}
}
}
`;

const variables = {
cartId,
lines: [
{
quantity: parseInt(quantity),
id: mainId,
},
],
};

try {
return await graphQLClient.request(updateCartMutation, variables);
} catch (error: any) {
throw new Error(error);
}
}

I than use the above mutation by invoking the following function:

handleUpdateExistingCartLines({

  quantity: (el.quantity + 1).toString(),

  mainId: el.merchandise.id,

});

I would like to use the same function to increment or decrement the quantity of an existing item in the cart.

This is the variables object that is sent with the mutation:

but I get the following error:

any help would much appreciated. Thank you

[Liam · Accepted solution]

Hi Alexander,

This sounds like a variable mismatch in your code - and looks slightly similar to this GitHub issue. If you follow a similar approach to what is advised there, can you resolve this?