[SalesForce] How to do field validation on lightning:recordEditForm with lightning:inputField

There is a way to bind the lighthning:inputField value to an Instance of an Object. Here is an Example code,

Parent Component:

<aura:component >

    <aura:attribute name="testContact" type="Contact" access="PUBLIC" default="{'sObjectType':'Contact'}"/>

    <div class="slds-box">
        <lightning:recordEditForm aura:id="recordEdit" objectApiName="Contact">
            <aura:iteration items="['LastName','Phone']" var="item">
                <c:inputFieldCmp aura:id="child" testContact="{!v.testContact}" fieldName="{!item}"/>
            </aura:iteration>
        </lightning:recordEditForm>
    </div> 

    <div  class="slds-m-around_medium">
        <lightning:button label="Save" variant="brand" onclick="{!c.recordSave}"/>
    </div>
</aura:component>

Child Component:

<aura:component >
    <aura:attribute name="testContact" type="Contact"/>
    <aura:attribute name="fieldName" type="String"/>

    <lightning:inputField aura:id='inputField' fieldName="{!v.fieldName}" onchange="{!c.change}"/>
</aura:component>

Child Component Controller:

({
    change: function(cmp,event,helper){

        cmp.get('v.testContact')[cmp.get("v.fieldName")] =  event.getSource().get('v.value');

    }
})

Parent Component Controller:

({
    recordSave : function(component, event, helper) {
        console.log(JSON.stringify(component.get('v.testContact')));
    }
 })

On this Way you can simply bind the values to an Object Instance and Validate. Also you can make it possible with giving recordId attribute to the lighthing:recordEditForm by just make the record as that testContact attribute.

A simple approach to validate field validity on lightning:inputField elements is by using built-in Lightning Component methods.

Component:

<lightning:recordEditForm
                          aura:id="form"
                          objectApiName="Account">
    <lightning:inputField
                          aura:id="field"
                          required="true"
                          fieldName="Name"/>
</lightning:recordEditForm>
<lightning:button label="Save" onclick="{!c.handleSave}"/>

Controller:

handleSave : function(component, event, helper) {
    // Make sure fields are in an iterable object by casting to array if not already
    let fields = component.find("field");
    if (fields) {
        fields = Array.isArray(fields) ? fields : [fields];
    }
    else {
        fields = [];
    }
    const valid = fields.reduce((validSoFar, field) => {
        // Return whether all fields up to this point are valid and whether current field is valid
        // reportValidity returns validity and also displays/clear message on element based on validity
        return (validSoFar && field.reportValidity());
    }, true);
    // If all fields aren't validated, throw error message
    if (!valid) {
        const toastEvent = $A.get("e.force:showToast");
        toastEvent.setParams({
            "message": "Review all error messages below to correct your data.",
            "type": "error"
        });
        toastEvent.fire();
    }
    // Otherwise submit save
    else {
        component.find("form").submit();
    }
}