hello i am having issues with loading nested associations im sure its been answered befor sorry for repeating if so i looked and could find nothing calendar events have jobs which have associated start and end locations
when i inspect like in the example i get nil association not loaded, am i not loading these associations correctly?

defmodule Site.CalendarEvent do
  use Site.Web, :model


  schema "calendar_event" do

      field :title, :string
      field :allDay, :string
      field :start, :string
      field :end, :string
      field :url, :string
      field :className, :string
      field :editable, :string
      field :startEditable, :string
      field :durationEditable, :string
      field :resourceEditable, :string
      field :rendering, :string
      field :overlap, :string
      field :uuid, :string
      field :constraint, :string
      field :source, :string
      field :color, :string
      field :backgroundColor, :string
      field :borderColor, :string
      field :textColor, :string
      field :date, Calecto.DateTime
      field :datetime, Calecto.DateTime
      field :posted_on, Calecto.DateTime

    timestamps()

    belongs_to :user, Site.User
    belongs_to :job, Site.Job
  end

  @doc """
  Builds a changeset based on the `struct` and `params`.
  """
  def changeset(struct, params \\ %{}) do
    struct
    |> cast(params, [:start, :uuid, :user_id, :title, :job_id])


  end
end

defmodule Site.Location do
use Site.Web, :model

  schema "locations" do
    field :address, :string
    field :city, :string
    field :state, :string
    field :zip, :string
    field :customer_id, :integer
    field :apt, :string
    belongs_to :job, Site.Job


    timestamps()
  end

  @doc """
  Builds a changeset based on the `struct` and `params`.
  """
  def changeset(struct, params \\ %{}) do
    struct
    |> cast(params, [ :address,  :city,  :state,  :zip, :customer_id, :job_id, :apt  ])
    |> validate_required([ :address, :city,  :state,  :zip])
    |> foreign_key_constraint(:customer)
  end
end

defmodule Site.Job do
  use Site.Web, :model

  schema "jobs" do

      field :type, :string

      field :status, :string
      field :uuid, :string

     field :amount, Money.Ecto.Type

    timestamps()
    has_one :calendar_events, Site.CalendarEvent
    has_one :lead, Site.Lead
    belongs_to :start_location, Site.Location
    belongs_to :end_location, Site.Location
    belongs_to :customer, Site.Customer
    belongs_to :user, Site.User
    has_many :events, Site.JobEvents
    has_many :locations, Site.Location
  end

  @doc """
  Builds a changeset based on the `struct` and `params`.
  """
  def changeset(struct, params \\ %{}) do
    struct
    |> cast(params, [:total_distance, :move_weight,  :type, :amount, :customer_id, :status, :user_id, :uuid, :start_location_id, :end_location_id])
    |> validate_required([:total_distance, :move_weight,  :type, :amount, :customer_id])
  end

    def updatechangeset(struct, params \\ %{}) do
      struct
          |> cast(params, [:uuid, :user_id, :status])


    end

      def locationschangeset(struct, params \\ %{}) do
      IO.inspect(params, label: "params")
          struct
              |> put_assoc(:start_location, params["start_location"])
              |> put_assoc(:end_location, params["end_location"])

        end
end

in the controller i have a function that i post to

def calendar(conn, params) do
import Ecto.Query, only: [from: 2]
user_id = conn.assigns.current_user.id


jobs = Site.Repo.all from e in CalendarEvent,
   where: e.user_id == ^user_id,
   preload: [job: :start_location, job: :end_location]

   render(conn, "booked.json", events: jobs )
  end

and in the view i serialize the json in the view as followes

def render("booked.json", %{events: events} ) do

events = case events do

nil -> []
_->  Enum.map(events, &events_json/1)
end
end

def events_json(event) do
job = event.job
IO.inspect(job, label: "event")
lead = job.lead
start_location = job.start_location
end_location = job.end_location

start_string = start_location.address <> " " <> start_location.city <> ", " <> start_location.state <> " " <> start_location.zip
end_string = end_location.address <> " " <> end_location.city <> ", " <> end_location.state <> " " <> end_location.zip

miles = to_string (ParseTransform.to_miles(job.total_distance))
title = "title"


        %{
          title:  title,
          description:  title,
          start: event.start,
          end: event.end,
          url: event.url ,
          from: start_string,
          to: end_string,
          className:  event.className ,
          editable:   event.editable ,
          startEditable:  event.startEditable ,
          durationEditable: event.durationEditable ,
          resourceEditable: event.resourceEditable ,
          rendering:       event.rendering ,
          overlap:   event.overlap ,
          constraint:   event.constraint ,
          source: event.source ,
          color:       event.color  ,
          backgroundColor: event.backgroundColor,
          borderColor:     event.borderColor,
          textColor:    event.textColor ,
          date:    event.date ,
          datetime: event.datetime,
          posted_on: event.posted_on
        }
      end