UploadServer.init({
            tmpDir: process.env.PWD + '/.uploads/tmp',
            uploadDir: process.env.PWD + '/.uploads',
            checkCreateDirectories: true, //create the directories for you
            finished: function(fileInfo, formFields) {
                fileInfo.customField = formFields.customField;
            },
            getDirectory: function(fileInfo, formFields) {
                if(formFields.customField) {
                    // to write in subdirectory give a postfix forward slash
                    return formFields.customField+"/";
                } else {
                    // to write in root directory return empty string or null
                    return ""; 
                }
            }
        });