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value-objects

This library provides convenience methods for creating value objects.

You may use the below table to decide which type is best for you. "Single Value" means the object will hold a single value, whereas "Array of Values" means the object can hold more than one value.

Quality Control

The following table is updated with each code update and is generated with the help of PhpUnit (unit testing tool) and Infection (mutation testing tool):

IsStringEnumType

Use this type when there is a set of fixed valid values, and your object represents a single value.

If there is a set of fixed valid values but your object represents an array of values, use IsStringArrayEnumType.

Example:

Usage:

IsIntEnumType

Use this type when there is a set of fixed valid values, and your object represents a single value.

If there is a set of fixed valid values but your object represents an array of values, use IsIntArrayEnumType.

Example:

Usage:

IsEmailType

Use this type when the value represents a single e-mail address. This trait uses IsStringType under the hood but performs standard e-mail validation.

Example:

Usage:

IsStringType

Use this type when the value represents a single string value, but there is no fixed set of valid values.

If you are expecting an e-mail address, you can use the IsEmailType trait instead, which will perform format validation checks.

Validation

To provide custom validation, override protected function validate(string $value) : void.

If you want to only validate the length of the string, you can call validateLength(string $value, ?int $minLength = null, ?int $maxLength = null) : void inside the validate method.

String transformation

If you want to transform the input value but not fail validation, override protected function transform(string $value) : string.

There are 3 convenience methods available that you can call inside transform if you want:

• trimAndLowerCase(string $value)
• trimAndUpperCase(string $value)
• trimAndCapitalise(string $value)

Example:

Usage:

IsIntType

Use this type when the value represents a single integer value, but there is no fixed list of valid values, or it is not feasible to write up each valid value.

Validation

You can provide custom validation rules by overriding protected function validate(int $value) : void. By default, it will validate that the value is a positive integer.

If you only want to validate that a value is between a certain minimum and maximum value, override protected static function minValidValue() : ?int and protected static function maxValidValue() : ?int. Returning NULL from either means there is no limitation to the minimum or the maximum value respectively.

Example:

Another example, for a value without any limitations:

Another example, for a value which has no upper limit but may never be below 5.

Another example which only allows odd values:

Usage:

IsFloatType

Use this type when the value represents a single float value.

Validation

You can provide custom validation rules by overriding protected function validate(float $value) : void. By default, it will only validate the float is above 0, but you can change this to allow unlimited values by overriding minValidValue.

If you only want to validate that a value is between a certain minimum and maximum value, override protected static function minValidValue() : ?float and protected static function maxValidValue() : ?float. Returning NULL from either means there is no limitation to the minimum or the maximum value respectively.

Example, which allows a value between 0 and 100, and which automatically crops any decimal points after the 3rd:

Usage:

IsIntStringMapType

Use this type if the value represents a single value which can be mapped between an integer and a string.

This may be useful when you e.g. store a value in the database as an integer (for faster indexing), but convert it to a string for a public API (for better readability).

Example:

Usage:

IsIntArrayEnumType

Use this type when the value represents an array of integer values, where each value must be one of a fixed list of values.

Useful when e.g. building filters, allowing to select a number of statuses or IDs (or others) to be included in the result.

Unique values

If each value can only appear once in the object, you have two options:

• If you want an exception to be thrown when duplicate values are being added (either via fromArray or via withValue), then override protected static function areValuesUnique() : bool and return true. An exception of type DuplicateValue will be thrown.
• If you do not want an exception to be thrown but want duplicate values to simply be silently ignored (both in fromArray and in withValue), override protected static function ignoreDuplicateValues() : bool and return true. If duplicate values are found, they are only added once to the array.

When both areValuesUnique and ignoreDuplicateValues return true, ignoreDuplicateValues takes precedence.

Example:

Usage:

IsStringArrayEnumType

Use this type when the value represents an array of string values, where each value must be one of a fixed list of values.

Useful when e.g. building filters, allowing to select a number of fields in the result.

Unique values

If each value can only appear once in the object, you have two options:

• If you want an exception to be thrown when duplicate values are being added (either via fromArray or via withValue), then override protected static function areValuesUnique() : bool and return true. An exception of type DuplicateValue will be thrown.
• If you do not want an exception to be thrown but want duplicate values to simply be silently ignored (both in fromArray and in withValue), override protected static function ignoreDuplicateValues() : bool and return true. If duplicate values are found, they are only added once to the array.

When both areValuesUnique and ignoreDuplicateValues return true, ignoreDuplicateValues takes precedence.

Example:

Usage:

IsClassArrayEnumType

Use this type when the value represents an array of class instances, and there is a list of valid values. This means the class instances represent enum types.

Example:

It is very similar to using IsIntArrayEnumType with the exception that each item in this array type is a class instance. It means individual items can be added without having to be converted into a scalar type, as in the usage example below:

Usage:

Because classes implementing IsClassArrayEnumType hold objects, you can perform method calls on returned elements, as in the example below:

Usage:

Unique values

By default, the same value can be added multiple times to the same instance. To control this behaviour, see the example below:

If each value can only appear once in the object, you have two options:

• If you want an exception to be thrown when duplicate values are being added (either via fromArray or via withValue), then override protected static function areValuesUnique() : bool and return true. An exception of type DuplicateValue will be thrown.
• If you do not want an exception to be thrown but want duplicate values to simply be silently ignored (both in fromArray and in withValue), override protected static function ignoreDuplicateValues() : bool and return true. If duplicate values are found, they are only added once to the array.

When both areValuesUnique and ignoreDuplicateValues return true, ignoreDuplicateValues takes precedence. Note: In order to perform these duplicate checks, the value object is converted into a string first. Make sure you have the __toString method implemented if you use custom classes and want these checks. (If you're using any of the types within this library, __toString is already implemented on them.)

Validation

By default, each element is already being validated for being an object, and an instance of the particular class returned by className(). However, if you want additional validation to be performed, you can override protected function validateEach(mixed $value) : void, which is executed for each value separately, both when instantiating it and when calling withValue. Note that this validation will also run before withoutValue, tryWithoutValue and contains, so you are notified when passing something entirely invalid rather than it being silently swallowed. Make sure to also call parent::validateEach($value); unless you want to repeat the default validation behaviour in your overridden version.

From raw values

If you want to instantiate your collection from "raw" values (as opposed to instances of a class) for convenience reasons (whilst internally converting them to the relevant instances), you can use fromRawValues.

Example:

This works for a conversion to instances that implement fromString, fromInt, fromBool, fromFloat, fromDouble, fromNumber or accept the relevant parameter through their constructor. Note that input types are NOT converted. That means if you pass a string, only the fromString factory method will be attempted. If none of the above are present or succeed, the trait will attempt to pass the value into the constructor of the target class. (Should this fail as well, a ConversionError is thrown.)

Custom conversion

If you would like to use the fromRawValues method but your target class has neither of the before-mentioned methods or ways of instantiating, you have three options:

1) Provide a custom callback

If you only need to do a custom conversion once, you can provide a callback to the fromRawValues method directly.

Example:

2) Override convertFromRaw

If you use a custom conversion more than once on the class, you have the option of overriding protected static function convertFromRaw(mixed $value) : object to automatically use your custom converter every time fromRawValues is called.

Example:

3) Implement your own factory method

Since everything is just a trait, you of course have the option of simply creating your own and replace fromRawValues. If you want to keep the same name for your own method and change the signature, just alias the trait's method and make it private.

Usage:

IsArrayEnumType

Use this type when the value represents an array of values of a type other than string, integer or an instance of a specific class (for those we have IsClassArrayEnumType respectively) and where there is a list of valid values.

Combination with other types

You can combine this type with any other type, e.g. to get an array of float types, or an array of int enum types, etc. The difference to using a combination of IsClassArrayEnumType for more information.

Unique values

By default, the same value can be added multiple times to the same instance. To control this behaviour, see the example below:

If each value can only appear once in the object, you have two options:

• If you want an exception to be thrown when duplicate values are being added (either via fromArray or via withValue), then override protected static function areValuesUnique() : bool and return true. An exception of type DuplicateValue will be thrown.
• If you do not want an exception to be thrown but want duplicate values to simply be silently ignored (both in fromArray and in withValue), override protected static function ignoreDuplicateValues() : bool and return true. If duplicate values are found, they are only added once to the array.

When both areValuesUnique and ignoreDuplicateValues return true, ignoreDuplicateValues takes precedence. Note: In order to perform these duplicate checks, the value object is converted into a string first. Make sure you have the __toString method implemented if you use custom classes and want these checks. (If you're using any of the types within this library, __toString is already implemented on them.)

Validation

You can provide custom validation by overriding protected function validateEach(mixed $value) : void, which is executed for each value separately, both when instantiating it and when calling withValue. Note that this validation will also run before withoutValue, tryWithoutValue and contains, so you are notified when passing something entirely invalid rather than it being silently swallowed.

Example:

Note that the example above is for demonstration purpose only - all of the above functionality comes out of the box by using IsClassArrayEnumType.

Usage:

IsClassCollectionType

Use this type when the value represents an array of values, where each value must be an instance of a class and there is no finite list of valid values. If there is a list of valid values, use IsArrayEnumType. If the values are not instances of a class, use IsCollectionType.

Unique values

If each value can only appear once in the object, you have two options:

• If you want an exception to be thrown when duplicate values are being added (either via fromArray or via withValue), then override protected static function areValuesUnique() : bool and return true. An exception of type DuplicateValue will be thrown.
• If you do not want an exception to be thrown but want duplicate values to simply be silently ignored (both in fromArray and in withValue), override protected static function ignoreDuplicateValues() : bool and return true. If duplicate values are found, they are only added once to the array.

When both areValuesUnique and ignoreDuplicateValues return true, ignoreDuplicateValues takes precedence.

Validation

You can provide custom validation by overriding protected function validateEach(mixed $value) : void, which is executed for each value separately, both when instantiating it and when calling withValue. Note that this validation will also run before withoutValue, tryWithoutValue and contains, so you are notified when passing something entirely invalid rather than it being silently swallowed.

Example:

From raw values

If you want to instantiate your collection from "raw" values (as opposed to instances of a class) for convenience reasons (whilst internally converting them to the relevant instances), you can use fromRawValues.

Example:

This works for a conversion to instances that implement fromString, fromInt, fromBool, fromFloat, fromDouble, fromNumber or accept the relevant parameter through their constructor. Note that input types are NOT converted. That means if you pass a string, only the fromString factory method will be attempted. If none of the above are present or succeed, the trait will attempt to pass the value into the constructor of the target class. (Should this fail as well, a ConversionError is thrown.)

Custom conversion

If you would like to use the fromRawValues method but your target class has neither of the before-mentioned methods or ways of instantiating, you have three options:

1) Provide a custom callback

If you only need to do a custom conversion once, you can provide a callback to the fromRawValues method directly.

Example:

2) Override convertFromRaw

If you use a custom conversion more than once on the class, you have the option of overriding protected static function convertFromRaw(mixed $value) : object to automatically use your custom converter every time fromRawValues is called.

Example:

3) Implement your own factory method

Since everything is just a trait, you of course have the option of simply creating your own and replace fromRawValues. If you want to keep the same name for your own method and change the signature, just alias the trait's method and make it private.

Usage:

IsCollectionType

Use this type when the value represents an array of values and there is no finite list of valid values. If there is a list of valid values, use IsStringArrayEnumType if applicable).

Combination with other types

You can combine this type with any other type, e.g. to get an array of float types, an array of e-mail addresses, etc. If you need each value to be an instance of a class, consider using IsClassCollectionType instead.

Unique values

If each value can only appear once in the object, you have two options:

• If you want an exception to be thrown when duplicate values are being added (either via fromArray or via withValue), then override protected static function areValuesUnique() : bool and return true. An exception of type DuplicateValue will be thrown.
• If you do not want an exception to be thrown but want duplicate values to simply be silently ignored (both in fromArray and in withValue), override protected static function ignoreDuplicateValues() : bool and return true. If duplicate values are found, they are only added once to the array.

When both areValuesUnique and ignoreDuplicateValues return true, ignoreDuplicateValues takes precedence.

Validation

You can provide custom validation by overriding protected function validateEach(mixed $value) : void, which is executed for each value separately, both when instantiating it and when calling withValue. Note that this validation will also run before withoutValue, tryWithoutValue and contains, so you are notified when passing something entirely invalid rather than it being silently swallowed.

It is recommended to set up validation, at least for the value type.

Value transformation

If you want to transform the input value but not fail validation, override protected function transformEach($value).

By also using the trait CanTransformStrings, you'll get 3 convenience methods that you can call inside transform if you want:

• trimAndLowerCase(string $value)
• trimAndUpperCase(string $value)
• trimAndCapitalise(string $value)

Example:

Usage: