I am trying to insert a record in a custom sObject 'Master_a__C' using lightning component. When i am clicking on save button, 'Unable to read sObject' error is coming upon controller's logic. Below are all the source code files. Any help is appreciated.

Component File :

<aura:component controller=RandomWorkSpace_Cntrl'> 
       <aura:attribute name="master_a" type="Master_a__C" default="{'sObjectType' : 'Master_a__C', 'Name' : ''}"/>

    <ui:inputText aura:id="name" value="{!v.master_a.Name}"  />
    <ui:button press="c.saveMaster" label="save"/>


RandomWorkSpace_Cntrl :

public with sharing class  RandomWorkSpace_Cntrl{

public static Master_a__C saveRecord(Master_a__C mas){
    upsert mas; 
    return mas; 
} }

Controller.js :

saveMaster : function(component, event, helper) {

    var master = component.get("v.master_a"); 
    var action = component.get("c.saveRecord");
    action.setParams({"mas" : master});

    console.log("mastera ---->" + JSON.stringify(master));

    action.setCallback(this, function(response){
       var state = response.getState();
        if(state == "SUCCESS" && component.isValid()){
           console.log("success") ;

            console.log("failed  ::: " + response.getError()[0].message); // Unable to read sObject





2 Answers 2


The error is due the case-sensitivity issue.It should haven been sobjectType instead of sObjectType in the default attribute of master_a

Always remember that attributes and it's values in component markup and variables you declare in controller.js and helper.js are all case-sensitive.

  • 1
    Thanks Praveen. It was indeed sobjectType instead of sObjectType.
    – s_saiyan
    Commented Jul 5, 2016 at 9:32
  • 3
    Curse the lightning gods! Thanks so much for this answer, I would never have figured that out. I've always used sObjectType in apex and never encountered sobjectType lowercase 'o'. Dang.
    – Doug Ayers
    Commented Oct 24, 2016 at 23:35
  • Blerg, thank you stack overflow. Nothing like trying to guess the deviations from lower camel case in internal apex. Commented Nov 29, 2016 at 18:53

When method in apex controller having parameter sObject: - Either set sobjectType attribute inside default in aura:attribute component Or object should have Id to call server side method.

When method in apex controller having specific sObject eg. Account: - No need to declare sobjectType inside default attribute of aura attribute component.

If above condition not satisfied it gives error unable to read sObject.

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