CODEWITHSUNDEEP
javascriptregexmongodbsessionmeteor
kerosene
kerosene

Reputation: 973

Meteor: Save RegExp Object to Session

I'm trying to save a regular expression as RegExp Object in a Meteor Session for a MongoDB query, but after Session.get() the RegExp object is just a empty object.

js

if (Meteor.isClient) {
    Meteor.startup(function () {
          var obj = {};
          obj['regexp'] = new RegExp("test");
          console.log("setting regular expression: " + obj['regexp']);
          Session.set("test", obj);
    });

    Template.test.events({
        'click button': function () {
            var regex = Session.get("test");
            console.log("now it is: ");
            console.log(regex['regexp']);
        }
    });
}

if (Meteor.isServer) {
}

html

<head>
  <title>meteor-regexp-session-test</title>
</head>

<body>
  {{> test}}
</body>

<template name="test">
  <button>hit the button and look at the console</button>
</template>

Any ideas why this is not working?

Thank in advance!

Upvotes: 1

Views: 608

Answers (3)

4Z4T4R
4Z4T4R

Reputation: 2458

There's a handy way to teach EJSON how to serialize/parse Regular Expressions (RegExp) documented in this SO question:

How to extend EJSON to serialize RegEx for Meteor Client-Server interactions?

Basically, we can extend the RegExp object class and use EJSON.addType to teach the serialization to both client and server. The options are enough of a critical piece of Regular Expressions that you should have the ability to store those too anywhere you want in perfectly valid JSON!

Hope this helps someone out there in the Universe. :)

Upvotes: 2

Hubert OG
Hubert OG

Reputation: 19544

You need to save the regex source instead:

var regex = new RegExp('test');
Session.set('regex', regex.source);

...

var restoredRegex = new RegExp(Session.get('regex'));
console.log(restoredRegex);

See: http://meteorpad.com/pad/KJHJtQPEapPhceXkx

Upvotes: 2

Kuba Wyrobek
Kuba Wyrobek

Reputation: 5273

Session package uses ReactiveDict under the hood.

ReactiveDict serializes value passed to Sessions.set(key, value):

// https://github.com/meteor/meteor/blob/devel/packages/reactive-dict/reactive-dict.js
// line 3-7:


var stringify = function (value) {
  if (value === undefined)
    return 'undefined';
  return EJSON.stringify(value);
};

Session.get(key) deserializes it with EJSON.parse:

// https://github.com/meteor/meteor/blob/devel/packages/reactive-dict/reactive-dict.js
// line 8-12:

var parse = function (serialized) {
  if (serialized === undefined || serialized === 'undefined')
    return undefined;
  return EJSON.parse(serialized);
};

It means Session doesn't support RegExp out of the box.

The solution for your issue is to create custom reactive data source, which will work similar to Session but will not serialize/deserialize value object.

Take a look here:

Upvotes: 1

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