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PHP Null Coalescing Operator

Summary : in this tutorial, you’ll learn about the PHP Null coalescing operator to assign a value to a variable if the variable doesn’t exist or null.

Introduction to the PHP null coalescing operator

When working with forms , you often need to check if a variable exists in the $_GET or $_POST by using the ternary operator in conjunction with the isset() construct. For example:

This example assigns the $_POST['name'] to the $name variable if $_POST['name'] exists and not null. Otherwise, it assigns the '' to the $name variable.

To make it more convenient, PHP 7.0 added support for a null coalescing operator that is syntactic sugar of a ternary operator and isset() :

In this example, the ?? is the null coalescing operator. It accepts two operands. If the first operand is null or doesn’t exist, the null coalescing operator returns the second operand. Otherwise, it returns the first one.

In the above example, if the variable name doesn’t exist in the $_POST array or it is null, the ?? operator will assign the string 'John' to the $name variable. See the following example:

As you can see clearly from the output, the ?? operator is like a gate that doesn’t allow null to pass through.

Stacking the PHP Null coalescing operators

PHP allows you to stack the null coalescing operators. For example:

In this example, since the $fullname , $first , and $last doesn’t exist, the $name will take the 'John' value.

PHP null coalescing assignment operator

The following example uses the null coalesing operator to assign the 0 to $counter if it is null or doesn’t exist:

The above statement repeats the variable $counter twice. To make it more concise, PHP 7.4 introduced the null coalescing assignment operator ( ??= ):

In this example, the ??= is the null coalescing assignment operator. It assigns the right operand to the left if the left operand is null. Otherwise, the coalescing assignment operator will do nothing.

It’s equivalent to the following:

In practice, you’ll use the null coalescing assignment operator to assign a default value to a variable if it is null.

• The null coalescing operator ( ?? ) is a syntactic sugar of the ternary operator and isset() .
• The null coalescing assignment operator assigns the right operand to the left one if the left operand is null.

Null Coalescing Operator in PHP: Embracing Graceful Defaults

Introduction.

The null coalescing operator introduced in PHP 7 provides a clean and succinct way to use a default value when a variable is null.

Getting Started with ‘??’

In PHP, the null coalescing operator (??) is a syntactic sugar construct that simplifies the task of checking for the existence and value of a variable. Prior to its introduction in PHP 7, developers would often utilize the isset() function combined with a ternary conditional to achieve a similar result. Let’s see this with a basic code example:

With the null coalescing operator, this simplifies to:

This approach immediately streamlines the code, making it more readable and easier to maintain.

Advancing with Null Coalescing

The operator is not only limited to simple variable checks but can be used with multiple operands, evaluating from left to right until it finds a non-null value. Let’s dive deeper with an advanced example:

This progresses through the $_GET, $_SESSION arrays, and ends with a literal if all else fails.

It also works seamlessly with functions and method calls. For instance:

In this scenario, if getUserFromDatabase($id) returns null, ‘fallback’ will be used.

Working with Complex Structures

The null coalescing operator is versatile, and can be directly applied to multi-dimensional arrays and even JSON objects. Consider the following example:

Let’s take it a step further with objects:

This code elegantly attempts to retrieve a profile picture, defaulting if nothing is returned.

Combining with Other PHP 7 Features

PHP 7 introduces other syntactic improvements such as the spaceship operator (<=>) for comparisons. Combine these with the null coalescing operator for powerful expressions. For example:

Real-World Scenarios

In real-world applications, embracing the null coalescing operator means focusing on the business logic rather than boilerplate checks. It particularly shines in scenarios involving configuration, forms, APIs, and conditional displays. The operator often becomes indispensable in modern PHP development workflows.

For instance, when processing API input:

Or, setting up a GUI with language fallbacks:

Good Practices and Pitfalls

While highly practical, there are scenarios where the null coalescing operator isn’t suitable. It should not replace proper validation and sanitization of user data, nor should it be overused in complex conditions where clearer logic may be needed for maintenance purposes. As with any tool in programming, using it judiciously is key.

Performance Implications

Performance-wise, the null coalescing operator is a favorable choice. Typically, it’s faster than combining isset() with a ternary operator due to reduced opcode generation. Let’s validate with a timed test:

You’re likely to notice slight but consistent speed advantages using the null coalescing operator.

The null coalescing operator in PHP streamlines default value assignment and contributes to cleaner code. As PHP continues to evolve, adopting such features not only leverages language efficiency but also enhances developer expressiveness and intent. In essence, the ?? operator fine-tunes the syntax dance that we perform every day as PHP developers.

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The PHP null coalescing operator (??) explained

by Nathan Sebhastian

Posted on Jul 11, 2022

Reading time: 2 minutes

The PHP null coalescing operator (also known as the double question mark ?? operator) is a new feature introduced in PHP 7.

The operator has two operands as follows:

The operator returns the first operand when the value is not null. Otherwise, it returns the second operand.

The operator allows you to set an if condition as shown below:

If the $_GET['user'] value is null in the example above, then assign the value nathan into the $user variable.

The null coalescing operator allows you to shorten a null check syntax that you need to do with the isset() function.

Before null coalescing operator, you may check for a null value using the ternary operator in conjunction with the isset() function like this:

When the user value is “unset” or null , assign nathan as the value of $user variable. Otherwise, it will assign $_POST['user'] as its value.

Stacking the null coalescing operands in PHP

The null coalescing operator allows you to stack as many operands as you need.

The operator will go from left to right looking for a non-null value:

When the value of $username is null or not set, PHP will look for the value of $first_name .

When $first_name is null or not set, PHP will look for the value of $last_name variable.

When $last_name variable is also null or not set, PHP will assign nathan as the value of $user variable.

Null coalescing assignment operator in PHP

The null coalescing operator can also be used to check a variable if it’s null.

You can then assign a value to the variable itself like this:

The syntax above means that PHP will check for the value of $user .

When $user is null or not set, then the value nathan will be assigned to it.

The code above is equivalent to the following isset() check:

And that’s how you assign a variable value using the null coalescing operator.

The PHP null coalescing operator is a new syntax introduced in PHP 7.

The operator returns the first operand if it exists and not null . Otherwise, it returns the second operand.

It’s a nice syntactic sugar that allows you to shorten the code for checking variable values using the isset() function.

Now you’ve learned how the null coalescing operator works in PHP. Nice work!

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• Best Practices ,

PHP null coalescing operator

Hello everyone, I'm relatively new to PHP and I recently came across the term "null coalescing operator." I have heard people mention it, but I'm not entirely sure what it does and how it can be used in my code. To give you some context, I am working on a project where I need to handle situations where variables might be null. I've been using conditionals and ternary operators to check for null values, but I've heard that the null coalescing operator could simplify my code. So my question is, what exactly is the null coalescing operator in PHP? How does it work and what are some practical use cases for it? I would appreciate it if someone could explain it to me in a way that is beginner-friendly and provide some code examples to illustrate its usage. Thank you in advance for your help!

All Replies

Hey there! I've been using the null coalescing operator in my PHP projects for a while now, and I must say, it's a fantastic addition to the language. As the name suggests, it helps in tackling situations where you need to handle null values. Here's how it works: the null coalescing operator (`??`) allows you to assign a default value to a variable if it is null. It's a concise way to check if a variable is null and provide an alternative value in a single expression. For example, let's say you have a variable `$name` that might be null. Instead of using an if statement or ternary operator, you can use the null coalescing operator like this: $defaultName = "Guest"; $fullName = $name ?? $defaultName; In this case, if `$name` is not null, the value of `$name` will be assigned to `$fullName`. However, if `$name` is null, `$defaultName` will be assigned to `$fullName`. It's a neat shortcut that keeps your code clean and concise. Another use case is when working with arrays. Suppose you have an associative array `$data` that may or may not have a key called `'email'`. To assign a default email if the `'email'` key is missing or null, you can use the null coalescing operator like this: $defaultEmail = "[email protected]"; $email = $data['email'] ?? $defaultEmail; If `$data['email']` exists and is not null, `$email` will be assigned its value. Otherwise, the default email address will be assigned. I've found the null coalescing operator to be handy in scenarios where you want to provide fallback values without writing lengthy if-else blocks or ternary statements. It definitely simplifies the code and makes it more readable. I hope this helps you understand and use the null coalescing operator effectively in your PHP projects. Feel free to ask if you have any more questions!

Hey everyone, I just wanted to chime in and share my experience with the null coalescing operator in PHP. I've been using it extensively in my projects, and it has proven to be a real time-saver. One particular use case where the null coalescing operator shines is when dealing with form input data. Typically, you would handle form submissions by checking if each field has a value or is null before using it. With the null coalescing operator, you can simplify this process and handle default values elegantly. Let's say you have a form with various inputs, such as name, email, and phone number. To avoid errors when these fields are left blank, you can utilize the null coalescing operator to assign default values. php $name = $_POST['name'] ?? "Anonymous"; $email = $_POST['email'] ?? "[email protected]"; $phone = $_POST['phone'] ?? "N/A"; In this example, if the corresponding `$_POST` variable is not null, the value will be assigned to the respective variable. However, if the field is null (left blank in the form), the null coalescing operator will assign the provided default value instead. This approach saves you from writing verbose conditional statements to handle each form input individually. It condenses the code and makes it more readable. Not only does the null coalescing operator simplify handling null values, but it also allows for cleaner code in cases where API responses or database query results may contain null values. Instead of manually checking each value, you can leverage the operator and set appropriate defaults or fallback values as needed. Overall, the null coalescing operator in PHP is a powerful tool for gracefully handling null values and reducing code complexity. I highly recommend integrating it into your PHP projects for smoother data handling. If you have any questions or need further clarification, feel free to ask. Happy coding!

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Hello all, I couldn't resist joining the discussion on the null coalescing operator in PHP. As a seasoned PHP developer, I can't stress enough how much it has improved my code readability and reduced boilerplate code. One practical use case I'd like to share is dealing with database results. We often fetch data from a database and assign it to variables, but sometimes certain fields may be null. That's where the null coalescing operator comes in handy. Imagine a scenario where you're fetching user records and want to display their names. Some users may not have specified their first name, so the database field would be null. Instead of writing lengthy if-else statements, the null coalescing operator provides an elegant solution. php $firstName = $user['first_name'] ?? "Unknown"; $lastName = $user['last_name'] ?? "Unknown"; With just a single line for each variable, we're able to handle null values effortlessly. If `first_name` or `last_name` is null, the corresponding variable will be assigned the default value of "Unknown". This not only streamlines the code but also improves legibility. It becomes much easier to track the intention of assigning default values to variables without bloating the codebase. Additionally, the null coalescing operator is a blessing when working with APIs. Sometimes APIs may have optional fields that could be null if not provided. By employing the null coalescing operator, you can quickly set fallback values to ensure your code continues to function seamlessly. To sum it up, the null coalescing operator is an essential tool that simplifies handling null values in PHP. Whether it's handling user input, database records, or API responses, this operator proves to be an elegant and efficient solution. If you have any questions or need further insights, feel free to ask. Happy coding, everyone!

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• Null Coalescing Operator

The PHP null coalescing operator, denoted by ?? , is a convenient feature introduced in PHP 7 that simplifies the way developers handle the default values for variables that may be null.

It provides a concise and readable syntax for dealing with potentially null values without the need for verbose ternary expressions.

Let’s move into its syntax.

Null Coalescing Operator Syntax

The syntax of the PHP null coalescing operator ( ?? ) is quite straightforward. It is used to handle situations where a variable may be null or not set, providing a default value if the variable is null. The basic syntax is as follows:

• $variable : The variable you want to check for null.
• $value : The value to use if $variable is not null.
• $default : The default value to use if $variable is null.

The following section provides an overview of how the null coalescing operator works. Let’s proceed.

How does the Null Coalescing Operator work?

This operation occurs in a single line, making the code more readable and concise compared to traditional conditional statements.

Here’s an example that shows you how it works:

The operator checks if the variable on the left side ( $variable in this case) is set and is not null. If it is set and not null, the expression evaluates to the value of $variable . If $variable is not set or is null, the expression evaluates to the value of $default .

This operator is especially useful when dealing with user input, configuration settings, or other scenarios where a variable might be null, and you want to provide a default value in case it is.

By moving into the section below, you will learn more about the null coalescing operator in PHP through examples.

Null Coalescing Operator Examples

Here is a basic example:

In this example, we are trying to retrieve the value of the username parameter from the $_GET array. If the username parameter exists and is not null, it will be assigned to the $username variable. However, if the username parameter is null or does not exist, the value ‘Guest’ will be assigned to $username . This is because of the null coalescing operator.

The null coalescing operator can also be chained together to provide default values for multiple variables. For example:

In this example, we are trying to retrieve the value of the username parameter from the $_GET array. If it is null or does not exist, we try to retrieve the value from the $_POST array. If this value is also null or does not exist, the value ‘Guest’ is assigned to $username .

The null coalescing operator is particularly useful when dealing with arrays or objects. Here’s an example:

In this example, we are trying to retrieve the value of the age key from the $person array. However, this key has a value of null. Using the null coalescing operator, we can assign the value ‘Unknown’ to the $age variable instead of null.

Moreover, it also can work with functions. For example:

In this example, we are calling the getUserName() function, which returns null. Using the null coalescing operator, we assign the value ‘Guest’ to $username instead of null.

Let’s summarize it.

Wrapping UP

The PHP 7 null coalescing operator streamlines the handling of default values for variables that may be null. Its concise and readable syntax simplifies the code, eliminating the need for verbose ternary expressions.

The operator, denoted by ?? , efficiently deals with situations where a variable may be null or unset, providing a default value if needed. The basic syntax involves checking a variable ( $variable ) and using a default value ( $default ) if the variable is null.

The operator proves beneficial in scenarios such as user input, configuration settings, or any case where a variable might be null, requiring a default value. Its single-line execution enhances code readability and conciseness, offering an alternative to traditional conditional statements.

Further exploration of the null coalescing operator includes chaining for multiple variables and its application with arrays, objects, and functions. Examples demonstrate its versatility, whether handling array elements, object properties, or function returns.

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PHP Operators Null Coalescing Operator (??)

Fastest entity framework extensions.

Null coalescing is a new operator introduced in PHP 7. This operator returns its first operand if it is set and not NULL . Otherwise it will return its second operand.

The following example:

is equivalent to both:

This operator can also be chained (with right-associative semantics):

which is an equivalent to:

Note: When using coalescing operator on string concatenation dont forget to use parentheses ()

This will output John only, and if its $firstName is null and $lastName is Doe it will output Unknown Doe . In order to output John Doe , we must use parentheses like this.

This will output John Doe instead of John only.

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In PHP 7, a new feature, null coalescing operator (??) has been introduced. It is used to replace the ternary operation in conjunction with isset() function. The Null coalescing operator returns its first operand if it exists and is not NULL; otherwise it returns its second operand.

It produces the following browser output −

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Null coalescing assignment operator in PHP

May 4, 2020 · PHP

When PHP 7.0 released , it has added many nice things in PHP’s toolbelt of utilities. One of the things among this was Null coalescing assignment operator (??) .

So basically, the operator can be used for the scenarios where you need to check if the variable is set or not before assigning it to an another variable. For instance, check the following code which you might be writing pre PHP 7.0 era.

The above code code can be reduced to following in PHP 7.0 by using null coalescing assignment operator like so.

Essentially, the null coalescing assignment operator returns its first operand if it exists and is not NULL ; otherwise it returns its second operand.

You can further make it more tidier by writing it as short-hand version like so.

As you can see in the example above, it’s now matter of just one line when you need to accomplish something like above. Looks pretty neat and clean, no?

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Nullish coalescing

What about default assignment while destructuring #, mixing and matching operators #, tell me about document.all #, support for nullish coalescing #.

• Web Development

What's the Difference Between ?? and ?: in PHP?

• Daniyal Hamid
• 06 Jun, 2021

?: (Elvis Operator)

The elvis operator ( ?: ) is actually a name used for shorthand ternary (which was introduced in PHP 5.3). It has the following syntax:

This is equivalent to:

?? (Null Coalescing Operator)

The null coalescing operator ( ?? ) was introduced in PHP 7, and it has the following syntax:

The table below shows a side-by-side comparison of the two operators against a given expression:

This post was published 14 May, 2018 (and was last revised 06 Jun, 2021 ) by Daniyal Hamid . Daniyal currently works as the Head of Engineering in Germany and has 20+ years of experience in software engineering, design and marketing. Please show your love and support by sharing this post .

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Nullish coalescing assignment (??=)

The nullish coalescing assignment ( ??= ) operator, also known as the logical nullish assignment operator, only evaluates the right operand and assigns to the left if the left operand is nullish ( null or undefined ).

Description

Nullish coalescing assignment short-circuits , meaning that x ??= y is equivalent to x ?? (x = y) , except that the expression x is only evaluated once.

No assignment is performed if the left-hand side is not nullish, due to short-circuiting of the nullish coalescing operator. For example, the following does not throw an error, despite x being const :

Neither would the following trigger the setter:

In fact, if x is not nullish, y is not evaluated at all.

Using nullish coalescing assignment

You can use the nullish coalescing assignment operator to apply default values to object properties. Compared to using destructuring and default values , ??= also applies the default value if the property has value null .

Specifications

Browser compatibility.

BCD tables only load in the browser with JavaScript enabled. Enable JavaScript to view data.

• Nullish coalescing operator ( ?? )

DEV Community

Posted on Mar 29, 2021

Nullish coalescing operator - explained

The Nullish coalescing operator is a new and additional JavaScript operator that has been available since June 2020 with ECMAScript 2020 (ES2020) of the programming language.

In addition to the well-known binary logical operators && (AND) and || (OR), it is the third operator non-binary and has the notation ?? .

It's always used when I want to explicitly check whether the value of a variable is available to use or, if the value is not available, to continue working with another value.

Here is the "classic" for me: Once with an if block, then in a "simplified" notation with the OR operator and last but not least in the notation with the new Nullish coalescing operator .

The first simplification, with the OR operator , works in most cases, but does not cover the case of working with boolean values.

But let's go through it step by step and see why the variants with the OR-operator work and then switch to the usually "better" Nullish coalescing operator .

OR-Operator

The binary logical operator ( Binary Logical Operator ) || (OR) is defined as follows:

{expression left side} || {expression right side}

I.e. if the expression on the left side delivers the value false the expression on the right side is interpreted, otherwise the expression on the left side is interpreted.

For our "simplification" from above...

It means that if the variable firstValue returns the value true , this value is returned (and in this case assigned to the variable secondValue ). However, if the variable firstValue returns false , the value of the right side is assigned to the variable secondValue - in my case the value DEFAULT_VALUE .

Step by step

Let's go through my example above step by step and see what I mean by...

and how the Nullish coalescing operator helps us here.

To do this, I put my example into a function and then execute it:

🥳 Everything works fine and the code also works with boolean values. 🥳

Reflexively, I feel like "simplifying" this code and using the possibilities of JavaScript for myself. Because I can determine that a value exists with an if (firstValue) , which leads to this version of my code:

😮 Oops...When I pass a false to the function I get back the value DEFAULT_VALUE and not the value false as expected 🤔

I go one step further and "simplify" my code again; and this time I use the OR operator :

I find the last "simplification" of my code even better. It takes away the if block and makes the code easier to read.

But both "simplifications" lead to the same unexpected result when I call the function with the value false .

What have I broken? 🤔

I haven't broken anything. I merely used, in both simplifications, the functionality of JavaScript that assumes that a value must be false ( false ) - that is, falsy . In the concrete case, with my if block and the OR operator , I check whether the value firstValue is false and then use the value DEFAULT_VALUE .

When is a value "falsy"

In JavaScript, a value is ( false ) or falsy if it is null , undefined , 0 or false .

And since this is the way it is in JavaScript, I have also changed the behaviour of my implementation with my "simplification" of the code 🤷.

Call the last two code examples with 0 (Zero):

Again, I want the value 0 (Zero) to be returned, but I get - logically - the value DEFAULT_VALUE 🤷

Let's get back to the actual implementation with the following expression in the if block:

From this derives my requirement that I want to check whether a value is nullish and not whether a value is falsy , as I have (unwittingly) done through my "simplifications".

What does nullish mean

With nullish it's meant that an expression must have the values null or undefined , only then it is nullish .

And exactly this is and was what I wanted to have with my first implementation and have implemented.

Can I not now "simplify" my introductory example? Do I have to manually query all nullish values in JavaScript myself?

😱😱😱 N O O O O 😱😱😱

The new one - Nullish coalescing operator ( ?? )

This is where the new one comes into play - the third logical operator in JavaScript.

Ladies and gentlemen the Nullish coalescing operator 🚀🚀🚀, which is written in JavaScript as ?? and is defined as follows:

{expression left side} ?? {expression right side}

This operator behaves similarly to the OR operator , but with the crucial difference...

It checks if the expression on the left side is "nullish" .

And not, as with the OR operator , whether the expression is false .

A few examples of the Nullish coalescing operator :

And with this knowledge, I can also "simplify" my code example again - like this...

I have one more...

In my examples with the Nullish coalescing operator you will have noticed that calling my "simplified" functions with an empty string ( "" ) does not result in DEFAULT_VALUE being returned.

This is not relevant to the way my example works, but I don't want to hide from you why this happens.

The answer is obvious: The nullish coalescing operator ( ?? ) checks whether a value is nullish , i.e. whether it's null or undefined . And an empty string ( "" ) is an empty string in JavaScript and thus neither null nor undefined - but falsy 🤣

Another example

Let's go one step further and work with boolean values like true and false this time. Let's say, in the context of a configuration that should give a sign of life exactly when we are online and assumes that we are (always) online (by default):

At this point in the text I have now reckoned with the false return value of the last call to the function, but it is not what I wanted.

I want the return value of the function to give me false when we're offline, i.e. when we set the key online in the passed object to false ( { online: false } ).

The known problem

From what I've learned, this wrong result of my function call makes sense. Because online || true has the following values with the last call: false || true .

And if the left side of the OR operator returns false the value of the expression on the right side is used (the value of the left side is falsy ) - in our case true 🤷.

The code works exactly as written, but not as expected.

Possible solutions

For my function that expects a configuration object, I could work with Destructuring and define a default value:

Or, instead of a configuration object, I use a boolean and check it with the strict inequality operator ( !== ):

But in this article the Nullish coalescing operator is the star 🤩 and for my configuration function also a solution:

• The first version of this article I wrote in my native language because there is a very active German JavaScript Community of which I am a part and which I would like to give something back to 🙇
• Or to say it with the hashtag of my trainer buddy WebDave : #CommunityRocks and in this case #GermanJavaScriptCommunityRocksToo 😉🚀😎

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