WordPress Customised Data Entry Interface – PT1

December 16, 2017

#AJAX #JavaScript #jQuery #JSON #PHP #Relational Models #WordPress

The client needed a customised backend for a WordPress site to facilitate data entry for a small catalogue of products (fewer than 100 items in total). There were 3 different specific types of product over multiple lines.

Clearly we need to begin by establishing a logical data model. The entity relationships look like this:

simple data model
Simple data model

[ Product ] is a Custom Post Type. I also created additional Custom Taxonomies for fields which would potentially need to be searchable using WP_Query or WP_Term_Query. This is a rather simplified version of what I successfully implemented – the client version included several additional taxonomy fields. [ Product Type ] and [ Product Line ] are logical entities. [ Product Version ] is arguably just a grouping of [ Product ] fields. We don’t actually need to worry about that distinction here – because of the way in which the underlying database structure is abstracted by the WordPress API.

Product - as a Custom Post Type
Product – as a Custom Post Type – with additional Custom Taxonomies
client products plugin
Client products plugin

In this case it made sense to separate the product catalogue functionality by coding it as a WordPress plugin. It comprises two files – the PHP and the JavaScript. With WordPress we can customise the backend user interface (the Dashboard) using custom meta boxes. The user needs to be able to enter the data for each field. As shown in the example here which is demonstrated with dummy data for an imaginary product. There is a good description of the metabox api at Theme Foundation’s WordPress Meta Boxes: a Comprehensive Developer’s Guide.

Custom Data Entry Interface
Custom data entry interface for [ Product Item ] fields
Custom Data Entry Interface
Custom data entry interface for [Product Item] fields

Some of those fields are just text boxes – the user can type in anything (though obviously that data needs to be sanitized before being written to the db). Sometimes the user will be selecting an image (or a PDF) from the Media Library (or uploading a new media item). Other times the user may selected from a predefined list (with radio buttons). Or the user may choose an item from a list where the option also exists to add a new item to the list.

When the user has completed or finished editing the fields for a product – then they publish, the same as any other post. But if a user is adding a new field item – for example a new [ Product Line ] then we want them to be able to do that without the need to reload the page in full. We use AJAX to update the database and the page. There is a good tutorial here at wpmudev.org – about how to implement and secure wp-ajax. Even with this being on the admin side, rather than user facing, it is important that the callback is properly secured. The following PHP shows how the metabox for [ Product Version ] is implemented:

taxonomy options
Taxonomy options

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Here is the corresponding JavaScript (jQuery). Any taxonomy which has an add button will use the same function. The client version has several additional similarly coded taxonomies which I am not including in this simplified example.

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This is how the AJAX side of that is implemented back in the PHP:

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Finally saving [ Product Version ] – called on post:

Show Code

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