Javascript Database API return result

Question

Hey all I've just been fooling around with the HTML5 Database API and I'm having trouble return the result from a function. Here is what I have.

var list = GetScenarios();

GetScenarios: function()
{

var scenarios;

// get all the scenarios
conn.transaction(function(_t) {

_t.executeSql('SELECT * FROM scenarios', [], function(_tr, _result) {

        scenarios = _result.rows;

    });
});

return scenarios;

}

I manage to get the rows from the db but the rows wont assign to the variable scenarios. I know its a scope thing but I can't think how to return the result from the GetScenatios function.

When I log _result.rows I have the data there but scenario is always undefined;

Any thoughts?

Here is how my js file is setup.

window.MyExtension = (function() 
{

    return ({

    OtherMethod: function() {   


        var list = window.MyExtension.GetScenarios();

    },

    GetScenarios: function() {

         ...see above

    }

}());

Your code is invalid JavaScript. GetScenarios: function() should be function GetScenarios(). It could be GetScenarios = function() but then it would have to appear before var list = GetScenarios();. — gilly3
– gilly3, Commented Nov 10, 2011 at 1:24
@gilly3, correct, except for the last remark: jsfiddle.net/FvdbT — stivlo
– stivlo, Commented Nov 10, 2011 at 1:29
@stivlo - Perhaps you misread my comment. function GetScenarios() works, as proven by your jsFiddle. But, GetScenarios = function() does not, as evidenced by this one: jsfiddle.net/FvdbT/1 — gilly3
– gilly3, Commented Nov 10, 2011 at 1:33
GetScenarios: function() works. I edited the post to reflect the js file setup — hooligan
– hooligan, Commented Nov 10, 2011 at 1:36
@gilly3 yes, I agree with that. hooligan, open your JavaScript console, for instance FireBug, and fix the syntax errors. — stivlo
– stivlo, Commented Nov 10, 2011 at 1:37

gilly3 · Accepted Answer · 2011-11-10 01:43:07Z

1

It looks like you are trying to return code from an asynchronous request as though it were synchronous. You need to add a callback parameter to GetScenarios():

function GetScenarios(callback) {
    conn.transaction(function(_t) {
        _t.executeSql('...', [], function(_tr, _result) {
            callback(_result.rows);
        });
    });
}

And change your calling code from:

var list = GetScenarios();
// do something with list

To, this:

GetScenarios(function (list) {
    // do something with list
});

answered Nov 10, 2011 at 1:43

gilly3

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1 Comment

hooligan Over a year ago

Perfecto! Thank you so much. Also turns out I have to use window.MyExtension.GetScenario() from within the object. Thanks Heaps

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