Magento2 save Custom shipment field by API

Question

I have add field track_url in table sales_shipment_track. I'm creating shipment with API

http://192.168.0.105/magento2/project/rest/V1/order/1292/ship


{
  "items": [
    {
      "order_item_id": 4473,
      "qty": 1
    }
  ],
  "notify": true,
  "tracks": [
    {
      "track_number": "3456789",
      "track_url": "http://192.168.0.105/demo/magento2?gf=13131",
      "title": "GEODIS",
      "carrier_code": "custom"
    }
  ]
}

everything was working fine before added new field track_url.

Now i'm getting error. "message": "Property \"TrackUrl\" does not have corresponding setter in class \"Magento\\Sales\\Api\\Data\\ShipmentTrackCreationInterface\".",

How can i add extension attribute for it?

EDIT I have add attribute in extension_attributes.xml.How can i save it with API?

    <config>
    <extension_attributes for="Magento\Sales\Api\Data\OrderInterface">
        <attribute code="dpd_relay_id" type="string"/>
        <attribute code="erp_exported" type="string"/>
    </extension_attributes>

    <extension_attributes for="Magento\Catalog\Api\Data\ProductInterface">
        <attribute code="finalprice" type="string"/>
        <attribute code="brand" type="string"/>
    </extension_attributes>

     <extension_attributes for="Magento\Sales\Api\Data\ShipmentTrackCreationInterface">
        <attribute code="track_url" type="string"/>
    </extension_attributes>

</config>

Answer 1

Try with below request payload

{
  "items": [
    {
      "order_item_id": 4473,
      "qty": 1
    }
  ],
  "notify": true,
  "tracks": [
    {
      "track_number": "3456789",
      "title": "GEODIS",
      "carrier_code": "custom",
      "extension_attributes" : {
            "track_url": "http://192.168.0.105/demo/magento2?gf=13131"
      }
    }
  ]
}.

You need to update extension_attributes.xml file as well. As you have not defined the xsd in config node.

 <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Api/etc/extension_attributes.xsd">
    <extension_attributes for="Magento\Sales\Api\Data\OrderInterface">
        <attribute code="dpd_relay_id" type="string"/>
        <attribute code="erp_exported" type="string"/>
    </extension_attributes>

    <extension_attributes for="Magento\Catalog\Api\Data\ProductInterface">
        <attribute code="finalprice" type="string"/>
        <attribute code="brand" type="string"/>
    </extension_attributes>

     <extension_attributes for="Magento\Sales\Api\Data\ShipmentTrackCreationInterface">
        <attribute code="track_url" type="string"/>
    </extension_attributes>

</config>

Let me know if you need further help.