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PHP Dataclass library

Dataclass allows you to quickly change your plain array to type-hinted PHP class with automatic denormalization of embeded objects and collections which normally requires much work if you use normalizers and denormalizers. Library is insipired by Python pydantic module. It uses type-hinting power available since PHP 7.4.

Main goal of this package is to provide fast way for having strictly type-hinted classes for further usage, for example to map request payload to strictly typed class so you can use it instead of array which may or may not match your requirements. It won't replace your data validation but will make you sure that f.x. received JSON payload matches types which your backend operations expect to receive. It's something like mentioned above pydantic BaseModel or TypeScript interface.

All you need is create class or two:

As next step pass main class name and received data, for example from received JSON to transform method:

To quickly map received data to fully functional dataclass:

You don't have to worry about passing null from json_decode, it will throw TransformException for root field if it's detected.

You don't have to worry about missing fields and invalid types as library detects all type-hinted requirements and throws TransformException with errors (ready to be served as response) pointing to exact fields with simple reason message, for example:

You can also use Transform::to method which is in fact called by transform helper function. Helper function will always use optimal settings for Transform objects (as soon as they appear).

Constructors

If you need to use constructor with type-hinted arguments you can do it, but in the limited way. The library only supports filling in constructor arguments with values from the payload. It means that constructor must use the same types and variable names as the class properties. For example:

Using different name or type for the constructor argument won't work. The goal is to support enforcing developer to fill in the properties.

Any constructor that contains any other parameter than the properties will throw UnsupportedException. Parameters must have the same type as properties. Order is irrelevant. If it's needed, only some subset of properties can exist in the constructor.

More examples

Please check out docs/ directory for more examples.

Installation

As simple as

Supported type hints

Attention: please be aware of using array type hints. They cannot be used (will throw UnsupportedException if detected) as PHP does not provide way to type-hint items of array. Please check Collections section below for further information.

Scalars

All four PHP scalars are supported.

Nullable fields

Type-hinting nullability is supported. You can safely use for example ?string to accept both string and null. Please be aware as using only ?string $field does not mean that transformed array may not contain this field. It only means that this value accepts null.

Default values

If you need to accept transformation of data which does not contain some fields you can use default values, for exmaple: ?string $field = null. Dataclass library will detect that this property does not exist in payload and will use default value instead.

Collections

PHP does not support type-hinting array fields if you need to embed collection of objects or scalars you have to use Collection class. You need to extend it with constructor with type-hinted arguments deconstruction, for example:

Type-hinted arrays like string[] were rejected in RFC so propably this behaviour will not change soon.

Library will check if provided values match type-hinting of constructor.

There is no possiblity to check minimum and maxiumum items but there may be such feature in next versions.

Please note that you can also use Collection as base class which you want to transform, for example:

Exceptions

TransformException - data does not match your schema

This is base exception you can expect. Every time your data (payload) passed to function transform(string $class, $data) or Transform::to will not match your type-hinted classes, you will receive TransformException with getErrors(): FieldError[] method which describes what really happened.

Every FieldError contains both field describing which field failed type check and reason describing in simple words why it has been rejected. If there are nested objects you can expect to receive field values like parentProperty.childrenProperty (levels separated by dot).

Class supports JSON serialization and will always return something like:

Please note that code field may be added in future.

UnsupportedException - only if your type-hints are not supported

Library does not cover all scenarios as you can define type hints which would not have strict context. For example if you use object property, it would not be possible to validate it as any object will match your schema. In such cases you can expect UnsupportedException.

Unsupported (yet?)

Intersection and union types

PHP 8.0 union types and PHP 8.1 intersection types are unsupported right now.

Enums

Native PHP 8.1 enums are unsupported right now.

Private and protected properties

All type-hinted fields must be public as for now. Implementing such feature is questionable as you would have to create getters for such properties which is unwanted overhead. Library is meant to create possiblity to define internal schemas for data received from remote systems (APIs, queues/bus messages, browsers).

Reflection cache

All reflection checks are made every time transform or Transform::to function is called. You can expect caching functionality for better performance soon.

Remarks

Please remember that goal of this package is not to fully validate data you receive but to create simple classes which makes your payloads fully type-hinted also when they have some complicated structure. You will not have to encode you classes in JSON with class fields as your type hints will tell your code what object or array should be created in place of some embeded values.

If you are creating API and you need enterprise-grade OpenAPI schema validation you should check hkarlstrom/openapi-validation-middleware and afterwards you can map received payload to type-hinted classes using this library! :)