WooCommerce Shipping Plugin "External Fetch"

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This blog post was published 7 years ago and may or may not have aged well. While reading please keep in mind that it may no longer be accurate or even relevant.

I just wrote the following shipping plugin for WooCommerce because existing plugins would not cover the case I’m working on. It is available on my GitHub account under the permissive MIT license.

https://github.com/michaelfranzl/woocommerce-shipping-external-fetch

woocommerce-shipping-external-fetch

Shipping Plugin for WooCommerce which HTTP PUTs the cart contents in JSON format to an external web service specified by protocol/host/port/URI, and receives the calculated shipping offer (costs, labels etc.) as JSON from that webservice.

Useful when the shipping calculation complexity exceeds the capabilities of other shipping calculation plugins.

The external shipping calculation application is, of course, business specific and thus not included in this repository. However, an example of a JSON request and reponse is shown below.

When the webservice is not reachable, not responsive, or returns HTTP status codes other than 200 (i.e. when it experiences a server error), this plugin offers free shipping to the customer, since technical problems are the ‘fault’ of the store owner and should not prevent a customer from completing an order. A setting to configure this behavior is not included, but it would be easy to add.

This plugin supports WooCommerce shipping zones. So, in theory you could have different web services dedicated to different shipping zones.

To add the plugin to an existing shipping zone:

  1. Go to WooCommerce -> Settings -> Shipping
  2. Click on “Manage shipping methods” below a Zone
  3. Click “Add shipping method” button
  4. Select “External Fetch” and click “Add shipping method” button
  5. Configure the Plugin by clicking on “Edit”
  6. Customize “Method title” and “Method description” and set the “JSON API Endpoint” to, for example http://localhost:4040/calculate

At this point you can add a product to the cart, set up a simple webserver listening at port 4040 on the same machine, and receive/send JSON as shown in the section “Examples” further below.

This plugin is for DEVELOPERS only and will likely remain in an ALPHA state.

Examples

Cart contents in JSON format as sent by this plugin:

{
  "contents": {
      "158f3069a435b314a80bdcb024f8e422": {
          "product_id": "313",
          "variation_id": "0",
          "quantity": "1",
          "line_total": "10",
          "line_subtotal": "10",
          "line_tax": "0",
          "line_subtotal_tax": "0",
          "shipping_class_slug": "shipping-class-slug1",
          "categories": [
              "cat-slug-1",
              "cat-slug-2"
          ],
          "attributes": {
              "blah": [
                  "content1",
                  "content2"
              ],
              "pa_delay": [
                  "10"
              ]
          },
          "dimensions": {
              "length": "",
              "width": "",
              "height": "14"
          },
          "purchase_note": "purchase note",
          "weight": "300",
          "downloadable": "0",
          "virtual": "0"
      },
      "e0e0fbbe4ccee55c005987fd6c6b75c8": {
          "product_id": "350",
          "variation_id": "353",
          "variation": {
              "attribute_color": "blue"
          },
          "quantity": "1",
          "line_total": "13",
          "line_subtotal": "13",
          "line_tax": "0",
          "line_subtotal_tax": "0",
          "data": {
              "post_type": "product_variation"
          },
          "shipping_class_slug": "bulky-items",
          "attributes": [
              "blue"
          ],
          "dimensions": {
              "length": "",
              "width": "",
              "height": "60"
          },
          "purchase_note": "",
          "weight": "400",
          "downloadable": "0",
          "virtual": "0"
      }
  },
  "contents_cost": "23",
  "user": {
      "ID": "0"
  },
  "destination": {
      "country": "US",
      "state": "",
      "postcode": "",
      "city": "",
      "address": "",
      "address_2": ""
  },
  "site": {
      "locale": "en_US"
  },
  "shipping_method": {
      "instance_id": "20"
  }
}

Response in JSON format as expected by this plugin:

This plugin will add the description values in a <div class="shipping_rate_description" below each selectable shipping rate entry on the checkout page to give the customer a better idea about the shipping method.

You can put a message into cart_no_shipping_available_html which will be added to the default WooCommerce message when there are no shipping methods available.

{
  "rates": [
    { 
      id: "20_1",
      cost: 11.1,
      label: "Standard Postal Service",
      description: "<b>without</b> Tracking"
    },
    { 
      id: "20_2",
      cost: 12.2,
      label: "Prio International",
      description: "<b>with</b> Tracking"
    },
  ],
  "notices": {
    "successes": [],
    "notices": ["This is a notice"],
    "errors": [],
  },
  "before_checkout_button_html: "Shipping prices calculated by plugin woocommerce-shipping-external-fetch!",
  "cart_no_shipping_available_html": ""
}
If you think you found a mistake in this blog post, or would like to suggest an improvement to this blog post, you can write me an e-mail to the address public dot michael at franzl dot name; as subject please use the prefix "Comment to blog post" and append the post title.
 
Copyright © 2023 Michael Franzl