Preventing Duplicate Form Submissions

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1

Hi!
I am creating a PTO tracking website for our employees. I have written code to prevent duplicate requests for the same dates off using this example: https://www.wix.com/code/home/forum/wix-tips-and-updates/example-no-database-duplicates
but it does not work on my page. This is my written code:

import wixData from ‘wix-data’ ;

export function searchForDuplicates ( value , info ) {
// info contains the hook context
// use the collectionName property to use function for multiple collections
return wixData . query ( “Employees” )
. eq ( “startDate” , value . startDate )
. find ()
. then (( results ) => {
return results . items . length ;
})
. catch (( err ) => {
let errorMsg = err ;
})
}
export function Employees_beforeUpdate ( item , context ) {
// Calls routine to check if value already exists in the collection.
// If value not found, then save record.
// Else, if value is found, then reject this insert to prevent duplicate values.
// Note: concurrent inserts may result in duplicates.
// Pass context to searchForDuplicates to use for multiple collections.
return searchForDuplicates ( item , context ). then (( res ) => {
if ( res > 0 ) {
return Promise . reject ( ‘This item already exists’ );
}
return item ;
});
}
The database is named “Employees” and ideally the code will search for both start and end date of the PTO request. The dates are entered into two date pickers: “Start Date” and “End Date”.

2

Hi, first of all your code disallows form permission for the same data even if it’s different member. If you want to make it per member, change your query.
Second , you used beforeUpdate instead of beforeInsert.
Third (optional), another thing you can do to make sure there’re no duplicates is to create the _id value based on concatenation of the member._id and the current date (after converting it to string). This way, every new submission attempt with same _id (i.e. same member._id and date) will be automatically rejected by the system.

3

Hi!
Thanks for your help.
I’m new to coding and this is the first time I have used a query.

What would I need to change the query to so that it is per member?
How would I go about concatenating the member._id?

4

I don’t know your collection schema, but I’ll assume you have a memberId filed that contains the memberId.

Then you can either do without concat:

//backend/data.js
import wixData from 'wix-data';
function lookUpForDuplicates(item, collection){
    let today = new Date();
    today.setHours(0,0,0,0);
    return wixData.query(collection)
        .ge('_createdDate',  today)
        .eq('memberId', item.memberId)
        .count();
}
export function Employees_beforeInsert(item, context) {
return lookUpForDuplicates(item, context.collectionName)
.then(r => {
    if(r){return Promise.reject('already submitted');}
        return item;
    })
}

Or with concat (shorter and works even if the same user submits 2 forms from 2 browser tabs at the same time):

export function Employees_beforeInsert(item, context) {
     let today = new Date();
      today.setHours(0,0,0,0);
    item._id = item.memberId + "--" + today.getTime();
     return item;
}
5

P.S as matter of fact, if you wish to disallow submitting in the same date based on the client time zone , you should create the _id on the front end (and for the first option without the concat, you should have clientDateString field in the collection, and create the clientDateString on the client side).

6

That worked! Thank you so much for your help!