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Laravel JSON Meta

A library for saving metadata in a JSON column, with strict type checking using PHPStan.

• Best for saving configuration options and other metadata
• Nested objects are not supported

Installation

Install the package via composer.

If you use PHPStan (highly recommended), add the following to your phpstan.neon file. This improves the type checking of the library.

Metadata or column?

When saving data, you have to decide between meta vs column. A general rule is that if that data is needed for a WHERE or ORDER BY, save it in a column. If not, you may save it in metadata. In most cases, configuration options are the best things to save in metadata.

(You can still use metadata in WHERE queries if your database engine supports JSON operations.)

Usage

Let's say you want to save metadata of blogs in a JSON column named meta.

First, add a JSON meta column to the table.

If your database does not support native JSON columns, Laravel will create a TEXT column, which works fine with this library.

Update the Model

• Add HasMeta trait
• Declare the defineMeta method

Definition

"Definition" is which data types you allow saving in the meta field. By defining them, you can make sure that incorrect data is never inserted by invalid user input or typos in your code. The following methods are available in the MetaDefinition class.

• string(string $name)
• integer(string $name)
• float(string $name)
• boolean(string $name)
• enum(string $name, string[]|class-string $values)

Default value

You should always set a default value for each metadata.

Use the default method to set the default value. The value should be of the same type as the type you defined.

Or, you can use nullable to set the default value to null.

In the above example, the type of seo_robots is now string|null.

Methods

The HasMeta trait adds the following methods to the model.

metaGet(string $name) : mixed

To get a meta value by name. The $name should be one of the names you defined in the metaDefinition function. If the value is not set, the default value will be returned.

metaGetAll() : array

To get all meta values. All keys you define in metaDefinition function will be set in the returned array, filled with default values if missing in the meta field.

metaSet(string|array $name, mixed $value) : void

Set meta $name to $value. In addition to static type checking via PHPStan, runtime type checking is done here to prevent invalid values from being saved.

You may also send an array as the first param to update multiple values.

Types

Include the PHPStan extension to get better type checking.

This registers the generic utility type meta-of<Model>. You can use this type to easily get the type of the meta fields as a constant array.

Why?

Why save metadata in a JSON column?

Let's see other options:

CASE 1: You could save metadata in separate columns.

• Maintaining a lot of columns is hard. You would need migrations to add new columns.
• Most of the time, users do not change the default values. So, most of the columns will be empty. It's much better to save them only when they are changed (which is what this library does). See "How data is saved" section below.
• Databases have max row size. In MYSQL it is around 65KB. At Hyvor Talk, we are closer to this limit, and it is one of the main reasons we developed this library. Note that in this library, we save metadata in TEXT, BLOB, and JSON columns, which are not counted in the row size limit.

CASE 2: You could save metadata in a separate table.

This is actually a good option. Check the laravel-meta library which has a similar concept like this library but saves data in a separate table.

How data is saved

When a new model is created, meta is NULL. Meta column only contains fields that were changed. For example, if you set seo_indexing to false, you will have the following JSON in the meta column:

This way, you will save a lot of space in the database.

Adding new metadata

Let's say you want to add a new metadata called seo_follow_external_links. This task is pretty easy. All you have to do is adding this to the definition.

Updating metadata

Updating is a bit tricky. Let's say you want to rename seo_indexing to seo_indexing_on. You could update the definition, but the problem is with the values that are already saved in the database.

How do you update this:

to this:

One option is to use JSON operations in the database. Or, use a custom script. Currently, this library does not provide this feature out of the box. But, if required in the future, we will add a command to do this. (Contributions/ideas are welcome)

Removing metadata

If you need to remove seo_indexing option from your application, you should first remove it in the meta definition.

You will still have old data saved in the database meta fields, but it should not be a problem as that data will be not be used even its there.

However, if you are required to delete those data (ex: for legal reasons), you will need an option similar to the "Updating metadata" section. Again, contributions are welcome.