# Validation functions

## Introduction

These functions are typically used on the `constraint` attribute of the `xf:bind` element. For example, as used by Form Builder:

```markup
<xf:bind
    id="control-1-bind"
    name="control-1"
    ref="control-1"
    type="xf:decimal"
    constraint="xxf:fraction-digits(2)"/>
```

All these functions annotate the context instance data node (element or attribute) with:

* a custom MIP of the same name
* with a value set to the single parameter to the function &#x20;

## xxf:upload-max-size()

\[SINCE Orbeon Forms 2017.1]

```
xxf:upload-max-size($bytes as xs:integer?) as xs:boolean
```

* `$bytes`
  * non-negative value: limited upload file size
  * `-1`: unlimited upload file size
  * `-2` or lower: ignored for the purpose of checking the upload file size
* always return `true()`, as the validation is only used at the time of upload

## xxf:upload-mediatypes()

\[SINCE Orbeon Forms 2017.1]

```
xxf:upload-mediatypes($mediatypes as xs:string?) as xs:boolean
```

* `$mediatypes`&#x20;
  * the value is a list of space- or comma-separated mediatype ranges
  * a mediatype range is one of:
    * `*/*`: all mediatypes allowed
    * `type/*`: all mediatypes with prefix `type` are allowed (for example `image/*`)
    * `type/subtype`: specific mediatype such as `image/jpeg`, `application/atom+xml`, `video/mp4`, etc.
* always return `true()`, as the validation is only used at the time of upload

## xxf:fraction-digits()

\[SINCE Orbeon Forms 2016.1]

```
xxf:fraction-digits($digits as xs:integer?) as xs:boolean
```

Return `true()` if the context item converted to a string via the `string()` function contains at most the number of consecutive digits specified by `$digits` after the decimal point `.`, or if there is no decimal point. Also return `true()` if `$digits` is the empty sequence.

Note the following:

* Trailing `0`s are not counted.
* Characters other than digits are ignored.

For example, if the context item is the string "abc123.d450f0g", the resulting consecutive digits after the decimal point considered are "45" and the number of consecutive digits after the decimal point is 2.

## xxf:max-length()

\[SINCE Orbeon Forms 4.10]

```
xxf:max-length($max as xs:integer?) as xs:boolean
```

Return `true()` if the context item converted to a string via the `string()` function contains at most the number of characters specified by `$max`. Also return `true()` if `$max` is the empty sequence.

Following [XPath 2.0](http://www.w3.org/TR/xpath-functions/#string-types):

> what is counted is the number of XML characters in the string (or equivalently, the number of Unicode code points). Some implementations may represent a code point above xFFFF using two 16-bit values known as a surrogate. A surrogate counts as one character, not two.

## xxf:min-length()

\[SINCE Orbeon Forms 4.10]

```
xxf:min-length($min as xs:integer?) as xs:boolean
```

Return `true()` if the context item converted to a string via the `string()` function contains at least the number of characters specified by `$min`. Also return `true()` if `$min` is the empty sequence.

Following [XPath 2.0](http://www.w3.org/TR/xpath-functions/#string-types):

> what is counted is the number of XML characters in the string (or equivalently, the number of Unicode code points). Some implementations may represent a code point above xFFFF using two 16-bit values known as a surrogate. A surrogate counts as one character, not two.

## xxf:negative()

\[SINCE Orbeon Forms 2016.1]

```
xxf:negative() as xs:boolean
```

* return `true()` if the context item converted to a string via the `string()` function parses as an `xs:decimal` which is negative
* return `false()` otherwise

## xxf:non-negative()

\[SINCE Orbeon Forms 2016.1]

```
xxf:non-negative() as xs:boolean
```

* return `true()` if the context item converted to a string via the `string()` function parses as an `xs:decimal` which is not negative
* return `false()` otherwise

## xxf:non-positive()

\[SINCE Orbeon Forms 2016.1]

```
xxf:non-positive() as xs:boolean
```

* return `true()` if the context item converted to a string via the `string()` function parses as an `xs:decimal` which is not positive
* return `false()` otherwise

## xxf:positive()

\[SINCE Orbeon Forms 2016.1]

```
xxf:positive() as xs:boolean
```

* return `true()` if the context item converted to a string via the `string()` function parses as an `xs:decimal` which is positive
* return `false()` otherwise