How calculate max value of many document?

[Marco Solci]

Hi

I want calculate max value of 'number' field of many documents so i created this function:

getMaxOrder3() {

        var highest;

        if (!highest) {

            this._db.allDocs({include_docs: true, descending: false}, function (err, doc) {

                doc.rows.forEach(function (row) {

                    if (highest == undefined || row.doc.Number > highest) 

                        highest = row.doc.Number;  

                });

                console.log('##---##'+highest); 

                return highest;

            });

        

        } else {

            return new Promise((resolve, reject) => resolve(highest));

        }

    } 

when i call the function in this way :

this.orderService.getMaxOrder3().then(data => this.order.Number = data);

            console.log("###"+this.order.Number);

the console show me 2 result:

###undefined

##---##9

where am I doing it wrong?

the function calculate correctly the maximum but when try to write it it's undefined.

thanks

[Nolan Lawson]

Hi, it looks like you forgot to put a "return" in your code, so it should be "return  this._db.allDocs..." . Since you forgot to "return", the Promise resolves to undefined.

You may want to read this blog post on Promises; I've been told it's helped people make sense of them: https://pouchdb.com/2015/05/18/we-have-a-problem-with-promises.html

Cheers,

Nolan