<aura:attribute name="sites" type="Site_Registration__c[]" />
<aura:attribute name="newSite" type="Site_Registration__c" access="global" default="{'sobjectType':'Site_Registration__c',
                                                                                     'Name':'Test',
                                                                                     'Company_Name__c':'',
                                                                                     'Project_Name__c':''
                                                                                     }" />

<input aura:id="companyName" placeholder="Company Name" class="slds-input" type="text" value="{!v.newSite.Company_Name__c}" required="true"/>

<input aura:id="projectName" placeholder="Project Name" class="slds-input" type="text" value="{!v.newSite.Project_Name__c}" required="true"/>

<lightning:button variant="brand" label="Submit" title="Submit" onclick="{!c.submitSite}" />

submitSite : function(component, event, helper) {

    var newSiteReg = component.get("v.newSite");

    console.log("Site Info Controller " + JSON.stringify(newSiteReg));

    helper.insertSiteRegHelper(component,newSiteReg);
},

({
    insertSiteRegHelper : function(component,siteReg) {

     var action= component.get("c.populateSiteReg");

        action.setParams({"siteReg" : siteReg
                      });
     action.setCallback(this, function(response)
     {
        var state = response.getState();
        if (state === "SUCCESS")
        {

            var sites = component.get("v.sites");
            sites.push(response.getReturnValue());
            component.set("v.sites", sites);
        }
        else
        {
        }
     });
     $A.enqueueAction(action);
    },
})

@AuraEnabled
    public static void populateSiteReg(Site_Registration__c siteReg)
    {

        if(siteReg != null){
            Database.insert(siteReg);
        }
    }