Where to trap Store / Proxy exception?

[danderson]

I was having a similar issue with the following error being thrown when the response does not include the defined root:

Uncaught TypeError: Cannot read property 'length' of undefined

I'm using the following override to get around the error, of course YMMV

Ext.override(Ext.data.Reader, {
    readRecords: function(data){
        this.rawData = data;
        
        data = this.getData(data);
        
        var root = this.getRoot(data);
        //BEGIN OVERRIDE - insert empty root if one does not exist
        if (root == undefined) {
            var rootName = this.root;
            data[rootName.toString()] = new Array();
            root = this.getRoot(data);
        }
        //END OVERRIDE 
        var total = root.length, success = true, value, records, recordCount;
        
        if (this.totalProperty) {
            value = parseInt(this.getTotal(data), 10);
            if (!isNaN(value)) {
                total = value;
            }
        }
        
        if (this.successProperty) {
            value = this.getSuccess(data);
            if (value === false || value === 'false') {
                success = false;
            }
        }
        
        records = this.extractData(root, true);
        recordCount = records.length;
        
        return new Ext.data.ResultSet({
            total: total || recordCount,
            count: recordCount,
            records: records,
            success: success
        });
    }
});

[Mis63]

I am having the same problem.
The success property of JSON response.

Can Sencha team tell us more about this : how to detect error sent in JSON response ?
Is a fix planned ?

[bclinton]

I am having the same problem.
The success property of JSON response.

Can Sencha team tell us more about this : how to detect error sent in JSON response ?
Is a fix planned ?

I don't know if this was the best place to put it, but I was able to check the success property in the readRecords method before the superclass.readRecords was called in an override like this:

(code added to the original method in red)

Ext.override(Ext.data.JsonReader, {
    readRecords: function(data) {
        //this has to be before the call to super because we use the meta data in the superclass readRecords
        if (data.metaData) {
            this.onMetaChange(data.metaData);
        }

       if (!data.success)
       {
            Ext.Msg.alert('Error', 'Success was false', Ext.emptyFn);
        }

        /**
         * DEPRECATED - will be removed in Ext JS 5.0. This is just a copy of this.rawData - use that instead
         * @property jsonData
         * @type Mixed
         */
        this.jsonData = data;

        return Ext.data.JsonReader.superclass.readRecords.call(this, data);
    }
});

I originally bypassed the "return Ext.data.JsonReader.superclass.readRecords.call(this, data);" line when success was false, but this gave me the "Uncaught TypeError: Cannot read property 'length' of undefined" error in the store.

To avoid this error I make sure I add an empty array for the store's root (in my case "rows") so my json looks like this:

{
    "success":false,
    "msg":"Your session has expired. You will be redirected to the login page.",
    "rows":[]
}

[interfasys]

None of these solutions will catch syntax errors thrown when the JSON object has a big problem. Does Sencha Touch provide a way to catch these other than using the window object?

[iamcam]

In response to @danderson's override. It works great, and I intend to keep it around until that time if/when Sencha changes the reader to handle these situations better.

[katamshut]

hi

you can do the following to catch any "success: false":

this.store.load({
                    scope   : this,
                    callback: function(records, operation, success) {
                        //the operation object contains all of the details of the load operation
                        if(operation.resultSet.success){
                            this.index();
                        } else {
                            Ext.Msg.alert('Failure','there was a failure: success is false');
                        }
                    }
                });

cheers
katam