Correct usage of Meteor.wrapAsync()

help
1

I’m trying to wrap an asynchronous function and call it synchronously using Meteor.wrapAsync(). I’m trying to move from the below server-side asynchronous call (which works fine):

if (!err) {
	Meteor.call("ldapLogin", username, password, Meteor.user());
}

where ldapLogin is in another server-side js file:

Meteor.methods({
	ldapLogin: function (username, password, userObj) {
		processLdapLogin(username, password, userObj);
	}
})

to something like this:

if (!err) {
	Meteor.methods({
		'ldapLogin': function(username, password) {
			var syncFunc = Meteor.wrapAsync(processLdapLogin);
			var result = syncFunc(username, password, Meteor.user());

			console.log(result);
		}
	});
	Meteor.call('ldapLogin', username, password);
}

Currently, I receive the following error:

Exception while simulating the effect of invoking ‘ldapLogin’ ReferenceError: processLdapLogin is not defined
at Meteor.methods.ldapLogin (http://localhost:3000/app/lib/ldap_shared.js?58bd12e667036c31820329433dfd394838cb27d4:24:61)

1 Like
2

You have a few typos in your sample. The method you call should have a matching method name defined, and since you’re passing in parameters you need to receive them. For example if you have:

Meteor.call('ldapLogin', username, password);

you would then have something like the following defined:

Meteor.methods({
  'ldapLogin': function (username, password) {
    check(username, String);
    check(password, String);
    // Assuming "processLdapLogin" exists somewhere else ...
    var syncFunc = Meteor.wrapAsync(processLdapLogin); 
    var result = syncFunc(username, password);
    console.log(result);
  }
});
1 Like
3

I do have a processLdapLogin method in another js file which was being called fine using the async Meteor.call. After making your suggested changes, processLdapLogin is not being called when I try to step through. This is what my code looks like now:

if (!err) {
	Meteor.call('ldapLogin', username, password);

	Meteor.methods({
		'ldapLogin': function(username, password) {
			check(username, String);
			check(password, String);
			var syncFunc = Meteor.wrapAsync(processLdapLogin);
			var result = syncFunc(username, password, Meteor.user());

			console.log(result);
		}
	});
}
4

Meteor.methods are not hoisted, so cannot be called before they are referenced.

However, I’m a little unclear what you’re trying to achieve here, as the context (specifically the client/server context) is not shown.

5

My bad, I’ve moved the calling statement. The code block above is within a server-side method called from the client on a sign-in event (login form submit). The processLdapLogin method is also on the server, in another js file. After moving the calling statement, I encounter the following error:

Exception while simulating the effect of invoking ‘ldapLogin’ ReferenceError: processLdapLogin is not defined at Meteor.call.Meteor.loginWithLDAP.Meteor.methods.ldapLogin (http://localhost:3000/app/lib/ldap_shared.js?ba17f688f0145921080673b6763ac0110a0502a5:24:61)

However, the processLdapLogin method does exist and I can ctrl-click into it in my WebStorm IDE, so not sure what I’m doing wrong at this point.

6

Are you sure the method is only on the server? The reference to .../lib/... in the exception suggests that your client has the method defined as well - in which case, it’s trying to run it as a simulation (and failing because processLdapLogin is not available on the client). As a workaround, you could just wrap the offending code in a if (Meteor.isServer) block. Better, you should recheck the structure of your code to ensure the method is defined only on the server (in a server/ folder).

It will be worth looking through the Meteor Guide on Methods.

7

When you say “the method”, are you referring to processLdapLogin? This is in fact a server-only method in server/ldap.js. When I only had the asynchronous method call, it would actually call the following Meteor Method in server/ldap.js:

Meteor.methods({
	ldapLogin: function (username, password, userObj) {
		processLdapLogin(username, password, userObj);
	}
})

However, I’ve since commented out the above in server/ldap.js and call processLdapLogin in server/ldap.js directly using Meteor.wrapAsync(processLdapLogin). Is this incorrect?

8

No, I mean where you have defined Meteor.methods({...