[SalesForce] Lightning button to update a record

A couple of things, Your getCase method returns an object of type "case", But, you are setting the object to a String in the init method of your js Controller.Additionally, as N.B pointed out, you seem to be passing 2 arguments when your apex method saveCase is expecting only one argument of type case.

Below is a refined version of your logic for your use-case. I have hard-coded "recordId" for demo purposes, do modify as required. And I notice that you have used individual aura:attributes for properties such as Status and Closed. Instead we ought to use compound attributes such as Object or Array of Objects for better logic.

Component:

<aura:component controller="SampleCaseController" implements="forceCommunity:availableForAllPageTypes" access="global" >
    <aura:handler name="init" value="{!this}" action="{!c.init}"/>
    <aura:attribute name="case" type="Case"/>

    <ui:button aura:id="mybtn" class="slds-button slds-button--brand" label="{!v.case.Status}" press="{!c.onclick}" disabled="{!v.case.IsClosed == true ? 'true' : 'false'}"/>

</aura:component>

We could have used aura:if for conditional rendering of status just like how we have used for "disabled" attribute. However extensive usage of aura:if is not recommended. Hence we will do our conditional checks in JS Controllers.

Apex Controller :

public class SampleCaseController {
    @AuraEnabled
    public static Case getCase(Id recordId){
        Case mycase = [SELECT Id, isClosed, Status FROM Case WHERE id=:recordId];
        return mycase;
    }
}

Controller.js :

({
    init : function(component, event, helper) {
        var recordId = "50061000007fHbf"; // for demo purpose

        var action = component.get("c.getCase");
        action.setParams({"recordId": recordId});

        action.setCallback(this, function(response) {
            var state = response.getState();
            if(component.isValid() && state == "SUCCESS"){
                var c = response.getReturnValue();
                component.set("v.case", c);
                window.setTimeout(
                    $A.getCallback(function () {
                        var button = component.find("mybtn");
                        if(c.Status == "New" || c.Status == "Awaiting Customer"){
                            button.set("v.label","Submit");
                        }else if(c.Status == "Closed"){
                            button.set("v.label","Closed");
                        }else {
                            button.set("v.label","Withdraw Case");
                        }

                    })
                );

            } else {
                console.log('There was a problem : '+response.getError());
            }
        });
        $A.enqueueAction(action);

    },
    onclick : function(component, event, helper) {
        console.log("Your save logic goes here");
    }

})

We will require window.setTimeout to provide small delay during the aura render cycle. If not the updated values will not reflect in the DOM.

Results :

When Status is new, the button text is set to "Submit"

Status anything other than New or Awaiting Customer, the text is set to "Withdraw Case"

Status Changed to Closed

Button Disabled in the Community and Status changed to closed

Update :

Change the methods below as shown and your save method should work during onclick.

Apex Controller :

@AuraEnabled
public static Case saveCase(Case caseRec){

        if (caseRec.Status == 'New' || caseRec.Status == 'Awaiting Customer') {
            caseRec.Status = 'Submitted';
        } else {
            caseRec.Status = 'Withdrawn';
        }

        update caseRec;
        return caseRec;
    }

I have changed the parameter from RecordId to caseRec as to avoid an additional database query.

Controller.js :

onclick : function(component, event, helper) {

        var action = component.get("c.saveCase");
        action.setParams({"caseRec": component.get("v.case")});

        action.setCallback(this, function(response) {
            var state = response.getState();
            if(component.isValid() && state == "SUCCESS"){
                var c = response.getReturnValue();
                component.set("v.case", c);
            } else {
                console.log('There was a problem : '+response.getError());
            }
        });
        $A.enqueueAction(action);

}

The other components do not require any change. The status would display as expected.

Results :

When status is set to working

The status is set to Withdraw case in community :

When you click on withdraw case, the button text and case status change to "Withdrawn"