After payment i want to save data into db

Am using razorpay After payment i want to save data into db but am not able to do here is my source code.

pay() {

    var options = {
      description: '////',
      image: 'xxxxxx',
      currency: 'INR',
      key: 'rzp_live_xxxxxxx',// this key need to chage for every app
      amount: this.total_ammount,
      name: 'demodemo',
      prefill: {
        email: this.email,
        contact: this.mobile,
        name: this.name
      },
      theme: {
        color: '#F37254'
      },
      modal: {
        ondismiss: function() {
          alert('dismissed')
        }
      }
    };

    var successCallback = function(payment_id) {
      alert('payment_id: ' + payment_id);
      var savepaymentinfo = function(){
        let postParams ={
          userid:this.userid,
          ammount:this.total_ammount,
          payment_valid:this.payment_valid,
      }
      alert(JSON.stringify(postParams))
      this.restApi.save_payment_plan(postParams).subscribe((data:any)=>{
        alert(JSON.stringify(data))
      },(error:any)=>{
        alert(JSON.stringify(error))
      })
      }
  
    };

    var cancelCallback = function(error) {
      alert(error.description + ' (Error ' + error.code + ')');
    };

    RazorpayCheckout.open(options, successCallback,cancelCallback);
  }

how to can i do that please help me anyone.
Thanks