HumHub Documentation (unofficial)

Expression extends BaseObject
in package
implements ExpressionInterface

Expression represents a DB expression that does not need escaping or quoting.

When an Expression object is embedded within a SQL statement or fragment, it will be replaced with the [[expression]] property value without any DB escaping or quoting. For example,

$expression = new Expression('NOW()');
$now = (new \yii\db\Query)->select($expression)->scalar();  // SELECT NOW();
echo $now; // prints the current date

Expression objects are mainly created for passing raw SQL expressions to methods of [[Query]], [[ActiveQuery]], and related classes.

An expression can also be bound with parameters specified via [[params]].

Tags
author

Qiang Xue qiang.xue@gmail.com

since
2.0

Table of Contents

Interfaces

ExpressionInterface
Interface ExpressionInterface should be used to mark classes, that should be built in a special way.

Properties

$expression  : string
$params  : array<string|int, mixed>

Methods

__call()  : mixed
Calls the named method which is not a class method.
__construct()  : mixed
Constructor.
__get()  : mixed
Returns the value of an object property.
__isset()  : bool
Checks if a property is set, i.e. defined and not null.
__set()  : mixed
Sets value of an object property.
__toString()  : string
String magic method.
__unset()  : mixed
Sets an object property to null.
canGetProperty()  : bool
Returns a value indicating whether a property can be read.
canSetProperty()  : bool
Returns a value indicating whether a property can be set.
className()  : string
Returns the fully qualified name of this class.
hasMethod()  : bool
Returns a value indicating whether a method is defined.
hasProperty()  : bool
Returns a value indicating whether a property is defined.
init()  : mixed
Initializes the object.

Properties

$expression

public string $expression

the DB expression

$params

public array<string|int, mixed> $params = []

list of parameters that should be bound for this expression. The keys are placeholders appearing in [[expression]] and the values are the corresponding parameter values.

Methods

__call()

Calls the named method which is not a class method.

public __call(string $name, array<string|int, mixed> $params) : mixed

Do not call this method directly as it is a PHP magic method that will be implicitly called when an unknown method is being invoked.

Parameters
$name : string

the method name

$params : array<string|int, mixed>

method parameters

Tags
throws
UnknownMethodException

when calling unknown method

Return values
mixed —

the method return value

__construct()

Constructor.

public __construct(string $expression[, array<string|int, mixed> $params = [] ][, array<string|int, mixed> $config = [] ]) : mixed
Parameters
$expression : string

the DB expression

$params : array<string|int, mixed> = []

parameters

$config : array<string|int, mixed> = []

name-value pairs that will be used to initialize the object properties

__get()

Returns the value of an object property.

public __get(string $name) : mixed

Do not call this method directly as it is a PHP magic method that will be implicitly called when executing $value = $object->property;.

Parameters
$name : string

the property name

Tags
throws
UnknownPropertyException

if the property is not defined

throws
InvalidCallException

if the property is write-only

see
__set()
Return values
mixed —

the property value

__isset()

Checks if a property is set, i.e. defined and not null.

public __isset(string $name) : bool

Do not call this method directly as it is a PHP magic method that will be implicitly called when executing isset($object->property).

Note that if the property is not defined, false will be returned.

Parameters
$name : string

the property name or the event name

Tags
see
https://www.php.net/manual/en/function.isset.php
Return values
bool —

whether the named property is set (not null).

__set()

Sets value of an object property.

public __set(string $name, mixed $value) : mixed

Do not call this method directly as it is a PHP magic method that will be implicitly called when executing $object->property = $value;.

Parameters
$name : string

the property name or the event name

$value : mixed

the property value

Tags
throws
UnknownPropertyException

if the property is not defined

throws
InvalidCallException

if the property is read-only

see
__get()

__toString()

String magic method.

public __toString() : string
Return values
string —

the DB expression.

__unset()

Sets an object property to null.

public __unset(string $name) : mixed

Do not call this method directly as it is a PHP magic method that will be implicitly called when executing unset($object->property).

Note that if the property is not defined, this method will do nothing. If the property is read-only, it will throw an exception.

Parameters
$name : string

the property name

Tags
throws
InvalidCallException

if the property is read only.

see
https://www.php.net/manual/en/function.unset.php

canGetProperty()

Returns a value indicating whether a property can be read.

public canGetProperty(string $name[, bool $checkVars = true ]) : bool

A property is readable if:

  • the class has a getter method associated with the specified name (in this case, property name is case-insensitive);
  • the class has a member variable with the specified name (when $checkVars is true);
Parameters
$name : string

the property name

$checkVars : bool = true

whether to treat member variables as properties

Tags
see
canSetProperty()
Return values
bool —

whether the property can be read

canSetProperty()

Returns a value indicating whether a property can be set.

public canSetProperty(string $name[, bool $checkVars = true ]) : bool

A property is writable if:

  • the class has a setter method associated with the specified name (in this case, property name is case-insensitive);
  • the class has a member variable with the specified name (when $checkVars is true);
Parameters
$name : string

the property name

$checkVars : bool = true

whether to treat member variables as properties

Tags
see
canGetProperty()
Return values
bool —

whether the property can be written

className()

Returns the fully qualified name of this class.

public static className() : string
Tags
deprecated

since 2.0.14. On PHP >=5.5, use ::class instead.

Return values
string —

the fully qualified name of this class.

hasMethod()

Returns a value indicating whether a method is defined.

public hasMethod(string $name) : bool

The default implementation is a call to php function method_exists(). You may override this method when you implemented the php magic method __call().

Parameters
$name : string

the method name

Return values
bool —

whether the method is defined

hasProperty()

Returns a value indicating whether a property is defined.

public hasProperty(string $name[, bool $checkVars = true ]) : bool

A property is defined if:

  • the class has a getter or setter method associated with the specified name (in this case, property name is case-insensitive);
  • the class has a member variable with the specified name (when $checkVars is true);
Parameters
$name : string

the property name

$checkVars : bool = true

whether to treat member variables as properties

Tags
see
canGetProperty()
see
canSetProperty()
Return values
bool —

whether the property is defined

init()

Initializes the object.

public init() : mixed

This method is invoked at the end of the constructor after the object is initialized with the given configuration.


        

        
    




    

    

                                

                

                                
    

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