How Get record in in lightning component in communities

force:hasRecordId is meant only for the Lightning experience and App builder and not the community builder .

<design:component>
   <design:attribute name="recordId" label="recordId" description="Salesforce Id of the record" />
 </design:component>

Create an attribute mapping to the design variable

<aura:component implements="forceCommunity:availableForAllPageTypes,force:appHostable,flexipage:availableForAllPageTypes">

 <!--ATTRIBUTES DECLARATION -->

 <aura:attribute name="recordId" type="String" default="{!recordId}"/>
   <aura:handler name="init" value="{!this}" action="{!c.getrecord}" />
 </aura:component>

Lets get the Id now in our JS controller

({
   getresults: function(component, event, helper) {
    console.log(component.get("v.recordId"));//print the Id 

  }
})