How to retrieve default route table id for a VPC

aws_default_route_table.tf

variable "vpcId" {
  default = "vpc-5f98eb36"
}

data "aws_route_table" "all" {
  vpc_id = "${var.vpcId}"
  filter {
    name = "association.main"
    values = ["true"]
  }
}

output "defaultRouteTableId" {
  value = "${data.aws_route_table.all.associations.0.route_table_id}"
}