Check if string variable is null or empty, or full of white spaces

Question

How can I check if a string variable is null or empty, or full with space characters in Twig? (Shortest possible, maybe an equivalent to CSharp's String.IsNullOrWhiteSpace() method)

Solution 1

There are already good answers, but I give my 2 cents too:

{% if foo|length %}

I was inspired by @GuillermoGutiérrez's filter trick.

But I think |length is safer as the "0"|trim expression will evaluates to false.

References :

• length
• codepad
• boolval

Solution 2

{% if your_variable is null or your_variable is empty %}

should check whether the variable is null or empty.

If you want to see if it's not null or empty just use the notoperator.

 {% if foo is not null and foo is not empty %}

See the docs:

• empty
• null
• "is" operator
• logical operators like "not"

Perhaps you might be interested in tests in twig generally.

Solution 3

I'd rather use just trim and empty:

{% if foo|trim is empty %} 

{% if foo|trim is not empty %} 

empty evaluates to true if the foo variable is:

• null
• false
• empty array
• empty string

Solution 4

{% if foo|trim %} seems to be enough (assuming that foo is the variable to check). If foo is not null, trim removes whitespaces. Also, if handles empty string or null as false, and true otherwise, so no more is required.

References:

• trim

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Comments

[DarkWanderer]

I'm not twig specialist, but shouldn't it be {% if foo is not null and foo is not empty %}? Otherwise seems like it will be always true.

[Marco Faustinelli]

too much of a hack, imho

[Marco Faustinelli]

@alanTiemblo - the most voted answer, I'd say. Still imho :-)

[Sandra]

the tests in twig link is broken, twig docs now live at symfony.com - eg twig.symfony.com/doc/3.x/tests/empty.html

[SirDerpington]

@Sandra Thank you for the hint, I've edited all links accordingly :)

[sschwei1]

@SirDerpington is the foo is (not) null part still necessary? Twig documentation states that empty also checks if the value equals null

[SirDerpington]

@sschwei1 that's a good catch. According to the documentation that's indeed true. Not sure how it was back in 2014 though