On my website I have a form with the fields: full name, email, phone #, and message (image below).

After someone fills out the form, I want to query my table to see if there are any items with the same email address, or phone # that the user gave to the form. If there IS an item with the same email/phone # then I want to retrieve that item’s "sharedID", then create a new item in the table with the submitted form information as well as the retrieved id.

Currently, I’m performing a dynamoDB query to achieve this (code below). However, I believe that I need to include the primary key (id) in the query. However, this is a problem because there’s no way of knowing an item’s id when querying (being that the id’s are randomly generated).

const checkForSameEmailOrPhone = () => {

const params = {
 TableName: "customers",
 ProjectionExpression: "sharedID",
 FilterExpression: "email_address = :givenEmail or phone_number = :givenNumber",
 ExpressionAttributeValues: {
     ":givenEmail": "xample@example.com",
     ":givenNumber": '7777777'
 }
};

docClient.query(params, function(err, data){
   if (err) {
     console.error('Error in GetItem', err);
   } else {
     console.log('data', data);
     function createItem() {
       const uniqueId = nanoid();
         let params = {
             TableName :"customers",
             ConditionExpression: "attribute_not_exists(z)",
             Item:{
               "id": uniqueId,
               "email_address": "address@email.com",
               "full_name": "a name",
               "phone_number": "822222222",
               "message": "different",
               "sharedId": data?.Items[0]?.id || uniqueId
             }
         };
         docClient.put(params, function(err, data) {
             if (err) {
               console.error('sdk ERROR', err);
             } else {
               console.log('success');
             }
         });
     };
     createItem();
   }
});
};

That being said, I was wondering if anyone could help me find a cost effective/efficient solution to retrieve the id of an item which contains the same email and phone # the user gave on the form.