CODEWITHSUNDEEP
javascriptnode.jsmongodbexpresswhere-clause
Metra
Metra

Reputation: 393

Passing a parameter in $where with MongoDB

I've a little problem with my script. I cannot passing a parameter (MYPARAMETER in the example) in the function in the '$where'.

You have an idea for help me ? Thanks.

var MYPARAMETER = "dqsd qsdqs &é&é";

MyCol.findOne({

    $where: function(MYPARAMETER) 
    { 
        var tab1="ÀÁÂÃÄÅàáâãäåÒÓÔÕÖØòóôõöøÈÉÊËèéêëÇçÌÍÎÏìíîïÙÚÛÜùúûüÿÑñ!#$€%&'`(),;:/@.*[]\|";
        var tab2=   "aaaaaaaaaaaaooooooooooooeeeeeeeecciiiiiiiiuuuuuuuuynn                      ";
        rep2=tab1.split('');
        rep=tab2.split('');
        parray=new Array();
        var i=-1;
        while(rep2[++i])
        {
            parray[rep2[i]]=rep[i]
        }
        var chaine = this.name.replace(/\s{1,}/g,"-");
        chaine = chaine.replace(/./g, function($0){return (parray[$0])?parray[$0]:$0 });
        chaine = chaine.replace(/\s/g,"");


        return (chaine == MYPARAMETER);
    }
},

Upvotes: 2

Views: 5350

Answers (4)

Simon Schärer
Simon Schärer

Reputation: 602

Use the $where operator to pass either a string containing a JavaScript expression or a full JavaScript function to the query system.

To pass a variable just create a string containing your local data like this (You don't need to parse it):

const myLocalVar = "test"    

const $where =  `function() { 
                return this.template.indexOf('${myLocalVar}')>=0
            }`

db.collection.find({$where})

Upvotes: 0

D K Sharma
D K Sharma

Reputation: 97

To use variables in $where query, first create mongo query as a string and then parse string to JSON when passing as parameter

Example: 

var query = '{"$where": "function() { return (\'' + address + '\').indexOf(this.city) >= 0 }"}';
db.city.find(JSON.parse(query);

Upvotes: 1

Ashish Maradiya
Ashish Maradiya

Reputation: 113

This one is works for me , Just try to store a query as a string in one variable then concat your variable in query string,

var local_var = 42

var query = "{$where: function() { return this.a == "+local_var+"}}"

db.test.find(query)

watch the reference exaple

Upvotes: 0

WiredPrairie
WiredPrairie

Reputation: 59763

A $where executes on the server, and thus wouldn't have access to a variable that was locally declared on another server. JavaScript should be used as a last resort generally in MongoDB, and this appears to go the other way and perform a LOT of very time consuming work.

You'd need to build the function as a string and include the value directly.

Upvotes: 3

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