Validate filters

Listing of filters for validation
ID Name Options Flags Description
FILTER_VALIDATE_BOOLEAN "boolean"   FILTER_NULL_ON_FAILURE

Returns TRUE for "1", "true", "on" and "yes". Returns FALSE otherwise.

If FILTER_NULL_ON_FAILURE is set, FALSE is returned only for "0", "false", "off", "no", and "", and NULL is returned for all non-boolean values.

FILTER_VALIDATE_EMAIL "validate_email"     Validates value as e-mail.
FILTER_VALIDATE_FLOAT "float" decimal FILTER_FLAG_ALLOW_THOUSAND Validates value as float.
FILTER_VALIDATE_INT "int" min_range, max_range FILTER_FLAG_ALLOW_OCTAL, FILTER_FLAG_ALLOW_HEX Validates value as integer, optionally from the specified range.
FILTER_VALIDATE_IP "validate_ip"   FILTER_FLAG_IPV4, FILTER_FLAG_IPV6, FILTER_FLAG_NO_PRIV_RANGE, FILTER_FLAG_NO_RES_RANGE Validates value as IP address, optionally only IPv4 or IPv6 or not from private or reserved ranges.
FILTER_VALIDATE_REGEXP "validate_regexp" regexp   Validates value against regexp, a Perl-compatible regular expression.
FILTER_VALIDATE_URL "validate_url"   FILTER_FLAG_PATH_REQUIRED, FILTER_FLAG_QUERY_REQUIRED Validates value as URL (according to » http://www.faqs.org/rfcs/rfc2396), optionally with required components. Note that the function will only find ASCII URLs to be valid; internationalized domain names (containing non-ASCII characters) will fail.

Note:

Numbers +0 and -0 are not valid integers but validate as floats.

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User Contributed Notes 10 notes

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10
bee kay two at em ee dot com
2 years ago
Notably missing is a way to validate text entry as printable,
printable multiline,
or printable and safe (tag free)

FILTER_VALIDATE_TEXT, which validates no special characters
perhaps with FILTER_FLAG_ALLOW_NEWLINE
and FILTER_FLAG_NOTAG to disallow tag starters
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5
Bastien
9 months ago
Rejection of so-called partial domains because of "missing" dot is not following section 2.3.5 of RFC 5321.

It says FQDNs are permitted, and com, org, or va are (well, may be) valids FQDNs. It depends on DNS, not on syntax.

Some TDLs (although few of them) have MX RRs, the for example "abuse@va" is correct.
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4
boy at relaxnow dot nl
1 year ago
FILTER_VALIDATE_URL does not work with URNs, examples of valid URIs according to RFC3986 and if they are accepted by FILTER_VALIDATE_URL:

[PASS] ftp://ftp.is.co.za.example.org/rfc/rfc1808.txt
[PASS] gopher://spinaltap.micro.umn.example.edu/00/Weather/California/Los%20Angeles
[PASS] http://www.math.uio.no.example.net/faq/compression-faq/part1.html
[PASS] mailto:mduerst@ifi.unizh.example.gov
[PASS] news:comp.infosystems.www.servers.unix
[PASS] telnet://melvyl.ucop.example.edu/
[PASS] http://www.ietf.org/rfc/rfc2396.txt
[PASS] ldap://[2001:db8::7]/c=GB?objectClass?one
[PASS] mailto:John.Doe@example.com
[PASS] news:comp.infosystems.www.servers.unix
[FAIL] tel:+1-816-555-1212
[PASS] telnet://192.0.2.16:80/
[FAIL] urn:oasis:names:specification:docbook:dtd:xml:4.1.2
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2
php dot net at piskvor dot org
3 years ago
FILTER_VALIDATE_EMAIL is discarding valid e-mail addresses containing IDN. Since there are real, live IDNs on the Internet, that means the filtered output is too strict, leading to false negatives.

Punycode-encoded IDN addresses pass the filter correctly; so before checking for validity, it is necessary to convert the e-mail address to punycode.
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2
rowan dot collins at gmail dot com
1 year ago
Regarding "partial" addresses with no . in the domain part, a comment in the source code (in ext/filter/logical_filters.c) justifies this rejection thus:

     * The regex below is based on a regex by Michael Rushton.
     * However, it is not identical.  I changed it to only consider routeable
     * addresses as valid.  Michael's regex considers a@b a valid address
     * which conflicts with section 2.3.5 of RFC 5321 which states that:
     *
     *   Only resolvable, fully-qualified domain names (FQDNs) are permitted
     *   when domain names are used in SMTP.  In other words, names that can
     *   be resolved to MX RRs or address (i.e., A or AAAA) RRs (as discussed
     *   in Section 5) are permitted, as are CNAME RRs whose targets can be
     *   resolved, in turn, to MX or address RRs.  Local nicknames or
     *   unqualified names MUST NOT be used.
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2
Clifton
3 years ago
FILTER_VALIDATE_EMAIL does NOT allow incomplete e-mail addresses to be validated as mentioned by Tomas.

Using the following code:

<?php
$email
= "clifton@example"; //Note the .com missing
echo "PHP Version: ".phpversion().'<br>';
if(
filter_var($email, FILTER_VALIDATE_EMAIL)){
    echo
$email.'<br>';
   
var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));
}else{
   
var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));   
}
?>

Returns:
PHP Version: 5.2.14 //On MY server, may be different depending on which version you have installed.
bool(false)

While the following code:

<?php
$email
= "clifton@example.com"; //Note the .com added
echo "PHP Version: ".phpversion().'<br>';
if(
filter_var($email, FILTER_VALIDATE_EMAIL)){
    echo
$email.'<br>';
   
var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));
}else{
   
var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));   
}
?>

Returns:
PHP Version: 5.2.14 //On MY server, may be different depending on which version you have installed.
clifton@example.com
string(16) "clifton@example.com"

This feature is only available for PHP Versions (PHP 5 >= 5.2.0) according to documentation. So make sure your version is correct.

Cheers,
Clifton
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0
Tom
2 years ago
Be aware!

In contrary to what the docs say (at least in PHP 5.3.1), this line:

$value = filter_var(FALSE, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE);

Will return NULL - not false. In other words: a boolean FALSE is not considered a valid boolean value by this function.

Also:

$value = filter_var("", FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE);

Will also return NULL - no matter what the docs say. So (string) FALSE is not considered a valid boolean input either.

Thus be aware the that correct usage/workaround for this filter is:

if (!is_bool($value)) {
    $value= filter_var($value, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE);
}

For those of you who feel this is counterintuitive, note that there is an issue filed for this in the bug-tracker.
So you might want to follow the discussion there or vote for issue #49510.
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-2
chastell at chastell dot net
3 years ago
example@example is a perfectly valid email address – I use chastell@localhost and chastell@devielle (my computer’s name) email addresses all the time and they get delivered just fine.
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-2
php at sethsyberg dot com
3 years ago
When validating floats, you must use the Identical/Not identical operators for proper validation of zeros:

This will not work as expected:
<?php
$x
= 0;
if (!
filter_var($x, FILTER_VALIDATE_FLOAT)) {
    echo
"$x is a valid float";
} else {
    echo
"$x is NOT a valid float";
}
?>

This will work as expected:
<?php
$x
= 0;
if (
filter_var($x, FILTER_VALIDATE_FLOAT)!== false) {
    echo
"$x is a valid float";
} else {
    echo
"$x is NOT a valid float";
}
?>
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-3
Griff
2 years ago
<< FILTER_VALIDATE_EMAIL allows incomplete e-mail addresses to be validated, for examle john@gmail will validate as a proper e-mail address >>

"Plain" hostnames with no dots are valid in email addresses -
for example, "me@localhost".
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