View source for XPathError class

__NOTOC__
An <var>XPathError</var> exception can be thrown by various methods in the [[XmlDoc API]].  It indicates an error either in the syntax of an [[XPath]] argument to the method, or in the results returned by that XPath expression.  The various read-only properties of an <var>XPathError</var> object (which can be set by the <var>[[Exceptions#Try and Catch|Catch]]</var> statement) provide information about the failed operation.

An example of using the <var>XPathError</var> exception is:
<p class="code">%err Object XPathError
Try
%d:Print('a b c')
Catch XPathError To %err
PrintText {~} = {%err:Reason}
PrintText {~} = {%err:Description}
PrintText {~} = {%err:CharacterPosition}
End Try
</p>
Since the expression (<code>a b c</code>) in the above invocation of the <var>[[Print (XmlDoc/XmlNode subroutine)|Print]]</var> method is not a valid
XPath expression, the above fragment will result in the following:
<p class="output">%err:Reason = SyntaxError
%err:Description = Expect "/" for new step or "[" for
predicate
%err:CharacterPosition = 3
</p>

This class is new in version 7.8 of the <var class="prod">Sirius Mods</var>.


==The XPathError methods==
{{Template:List of XPathError methods}}

The methods in the class are described in the subsections that follow. In addition:
<ul>
<li>[[Notation conventions for methods|"Notation conventions for methods"]] has information
about the conventions followed. 
<li>[[XPathError methods syntax|"XPathError methods syntax"]] is a single page that contains the syntax diagrams of all the methods in the class.
</ul>


==CharacterPosition property==
{{Template:XPathError:CharacterPosition subtitle}}

===Syntax===
{{Template:XPathError:CharacterPosition syntax}}

====Syntax terms====
<table class="syntaxTable">
<tr><th>%number</th>
<td>The position of the character at which the exception was thrown.</td></tr>

<tr><th>xPathError</th>
<td>An <var>XPathError</var> object.</td></tr>
</table>


==Description property==
{{Template:XPathError:Description subtitle}}

===Syntax===
{{Template:XPathError:Description syntax}}

====Syntax terms====
<table class="syntaxTable">
<tr><th>%string</th>
<td>A string to receive the description of the exception.</td></tr>

<tr><th>xPathError</th>
<td>An <var>XPathError</var> object.</td></tr>
</table>


==New constructor==
{{Template:XPathError:New subtitle}}

Each argument to <var>New</var> sets the value of the corresponding property of the newly constructed <var>XPathError</var> object.

===Syntax===
{{Template:XPathError:New syntax}}

====Syntax terms====
<table class="syntaxTable">

<tr><th>%xPathError</th>
<td>A reference to an instance of an <var>XPathError</var> object.

<tr><th><var>[%(XPathError):]</var></th>
<td>The class name in parentheses denotes a <var>[[Notation conventions for methods#Constructors|Constructor]]</var>.</td></tr>

<tr><th><var>Reason</var></th>
<td>This [[Methods#Named parameters|name required]] parameter is an <var>[[#XPathErrorReason enumeration|XPathErrorReason]]</var> enumeration value which specifies the value to be assigned to the exception object's <var>[[Reason (XPathError property)|Reason]]</var> property.
The <var>Reason</var> parameter is '''not''' optional.</td></tr>

<tr><th><var>Description</var></th>
<td>This optional, name required, parameter specifies the string value (<var class="term">string</var>) to be assigned to the object's <var>[[Description (XPathError property)|Description]]</var> property.</td></tr>

<tr><th><var>CharacterPosition</var></th>
<td>This optional, name required, parameter specifies the numeric value (<var class="term">number</var>) to be assigned to the object's <var>[[CharacterPosition (XPathError property)|CharacterPosition]]</var> property.</td></tr>
</table>


==Reason property==
{{Template:XPathError:Reason subtitle}}

===Syntax===
{{Template:XPathError:Reason syntax}}

====Syntax terms====
<table class="syntaxTable">
<tr><th>%xPathErrorReason</th>
<td>This <var>XPathErrorReason</var> enumeration value (see below) describes the reason for the translation failure.</td></tr>

<tr><th>xPathError</th>
<td>An <var>XPathError</var> object.</td></tr>
</table>

====XPathErrorReason enumeration====
An <var>XPathErrorReason</var> [[Enumerations|enumeration]] may have one of the following values:
<table class="optionTable">
<tr><th>SyntaxError</th>
<td>A violation of the syntax of an XPath expression.</td></tr>

<tr><th>EmptyResult</th>
<td>No nodes are matched by the XPath expression, and the method
requires at least one matching node.</td></tr>
</table>

'''Note:''' As with all enumerations, the <var>ToString</var> method implicitly converts an enumeration value to a character string whose value is the name of the enumeration value. For more information about methods available to all enumerations, see [[Enumerations#Common enumeration methods|"Common enumeration methods"]].

[[Category:System exception classes]]