Extending Models with Content and Content-Type

Traditional relational databases have structure, so we use migrations to manage that structure in Laravel.

This is cool, until you find yourself creating tables for things that you don't need tables for, because none of the tables' columns act as foreign keys to keys on other tables.

E.g. a user_settings table would have a structure like

id	user_id	key	value
1	2	bg_color	red
2	3	bg_color	blue

Now, if you wanted to store more complicated information like what ring-tone to play when a particular user calls, you'd have to either extend the user_settings with a migration to have a column like target_user_id, or have a nested key like <target-user-id>/ringtone.

Either choice would present some challenge, grouping settings to resolve during presentation.

Presenting Content and Content-Type

These represent two Eloquent models that map to tables with schema:

ContentType

name	type	description
id	int	Incremental ID
model	varchar	A reference to class name of the Eloquent Model that owns this
name	varchar	A lower-case name of the content-type e.g. `bg_color`
display_name	varchar	A more user-friendly name, in case you need to display
format	varchar	One of `string`, `number`, `boolean`, `datetime`, `object` or `array`
related_to	int	A reference to another `ContentType` id that this is a child of
created_at	timestamp	When this was created
updated_at	timestamp	When last this was updated

Content

name	type	description
id	int	Incremental ID
model_id	int	A reference to the id of the model instance that owns this content
content_type_id	int	A reference to the content-type that this content belongs to
value	varchar	The actual value of this content
created_at	timestamp	When this was created
updated_at	timestamp	When last this was updated

Rules

Only a content-type with an array format is allowed to have multiple contents.
Only a content-type with an object format is allowed to have child content-type(s).
A child content-type is one with its related_to value set to the id of another content-type.
For content-type(s) with primitive format values, the values of their content must match with their formats. E.g. a content-type with number format, can only have a content with a number value such as 100 or 0.2345.

The Advantage(s)

When retrieving contents, the response can extend an existing model with $builder->with('contents.type'). Here's an example of content for a department model:

{
    "id": 1,
    "name": "Physics",
    "hod_id": 1,
    "faculty_id": 1,
    "created_at": "2018-08-01 08:23:36",
    "updated_at": "2018-08-01 08:23:36",
    "contents": [
        {
            "id": 1,
            "owner_id": 1,
            "content_type_id": 1,
            "value": "array-value-1",
            "created_at": "2018-08-01 08:23:36",
            "updated_at": "2018-08-01 08:23:36",
            "type": {
                "id": 1,
                "school_id": 1,
                "type": "App\\Models\\Department",
                "name": "type-1",
                "display_name": "Type 1",
                "format": "array",
                "related_to": null,
                "created_at": "2018-08-01 08:23:36",
                "updated_at": "2018-08-01 08:23:36"
            }
        }
    ]
}

The response can be transformed to become nested, and include only important details.

{
    "id": 1,
    "name": "Physics",
    "hod_id": 1,
    "faculty_id": 1,
    "created_at": "2018-08-01 08:23:36",
    "updated_at": "2018-08-01 08:23:36",
    "content": {
        "type-1": [
            "array-value-1",
            "array-value-2",
            "array-value-3"
        ],
        "type-9": "Value 1",
        "type-6": {
            "type-4": "object-value-1",
            "type-8": 123
        }
    }
}