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Use the arc:check keyword with or without a value parameter. Without a value parameter, it ensures that an attribute is present in an item and that it is not a null string before the body of arc:check is executed. If you specify a value parameter, the arc:check body executes only if the expression evaluates to true. Other values are considered false. The evaluation is case-insensitive. Like other simple conditionals in Script, arc:check can be paired with an arc:else keyword.
Unlike arc:equals, arc:check does not throw an exception if the attribute does not exist in the item.

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Parameters

  • item: The item in which to check the attribute. Specifying an item is not required. If no item is specified, the default output item is used.
  • attr: The name of the attribute to check. This parameter is required.
  • value: An expression that evaluates to true or false. For example, the result of a formatter that returns true or false.
  • action: The action to execute if the expression evaluates to true. Allowed values are break and continue.

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Control Attributes

None

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Examples

Check for the presence of an attribute on an item This example uses arc:check to check for the presence of the number attribute on the result item. If true, a header is added to the message. Otherwise, an error is thrown. 
<arc:set attr="result.number" value="95" />

<!-- Check that the number attribute exists on the result item first. -->
<arc:check attr="result.number">
  <!-- If true, add a header. -->
  <arc:if exp="[result.number | lessthan(100)]">
    <arc:set attr="out.header:numberlessthan100" value="true" />
    <arc:set attr="out.filepath" value="[filepath]" />
    <arc:push item="out" />
    <!-- Else, throw an error. -->
    <arc:else>
      <arc:throw code="HighValue" desc="The target value was above the desired value of 100." />
    </arc:else>
  </arc:if>
</arc:check>
Check for a value during enumeration This example enumerates over a range from 1 to 10 and uses arc:check to check the iteration value. If it is equal to 5, break out of the enumeration. If the value is not equal to 5, create a file with some data and push the file as output. 
<arc:enum range="1..10">
  <!-- Check the current iteration and break if it is equal to 5. -->
  <arc:check value="[_value | equals(5)]" action="break" />
  <!-- For iterations not equal to 5, create a file and push it as output. -->
  <arc:setm item="out">
    FileName=Result_[_value].txt
    Data=The enumeration value is [_value].
  </arc:setm>
  <arc:push item="out" />
</arc:enum>

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See Also