Javascript List Button Not working

Question

I am trying to create a list button to update a status field on a list of records, but I have problems with the syntax. Please help..

{!REQUIRESCRIPT("/soap/ajax/19.0/connection.js")} 

var url = parent.location.href; 
var records = {!GETRECORDIDS($ObjectType.Tasks__c )}; 

var updateRecords = []; 

if (records[0] == null) { 
alert("Please select at least one record to update."); 
} else { 

for (var a=0; a<records.length; a++) { 

    var update_Tasks = new sforce.SObject("{!Tasks__c}"); 
    update_{!Tasks__c.Id} = records[a]; 

    update_{!Tasks__c.Status__c} = "Completed"; 
    updateRecords.push(update_Tasks__c); 

    }
    result = sforce.connection.update(updateRecords); 

    parent.location.href = url; 
}

Error is in the {!GETRECORDIDS ($ObjectType.... I am using a custom object and not sure how to write it.

Answer 1

Your object names look fine but you've got merge syntax {! } in your javascript that shouldn't be there. I've modified your javascript variables in the code below to make it a bit clearer what is happening in the loop. You may still have field API name issues to clear up.

{!REQUIRESCRIPT("/soap/ajax/19.0/connection.js")} 

var url = parent.location.href; 
var records = {!GETRECORDIDS($ObjectType.Tasks__c)}; 

var recordsToUpdate = []; 

if (records[0] == null) { 
    alert("Please select at least one record to update."); 
} else { 

    for (var a=0; a<records.length; a++) { 

        var taskToUpdate = new sforce.SObject("{!Tasks__c}"); 
        taskToUpdate.Id = records[a]; 

        taskToUpdate.Status__c = "Completed"; 
        recordsToUpdate.push(taskToUpdate); 

        }

    var result = sforce.connection.update(recordsToUpdate); 

    // you probably want to check what is in 'result' and look for success before 
    // redirecting the browser to the new URL

    parent.location.href = url; 
}

Answer 2

Building on Mark's answer, the final piece of the puzzle is that your sObject creation syntax is not quite right.

You don't need {!} at this point.

Change var taskToUpdate = new sforce.SObject("{!Tasks__c}");

To var taskToUpdate = new sforce.SObject("Tasks__c");

The curly bracket syntax is a static way to tell salesforce that you want the value in the curly bracket to be replaced with some actual value. In this case, you don't want that - you want to create an object of type "Tasks__c"