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RegEx on Message Context Search Field Expression Plugin

The RegEx on Message Context plugin reads the value of one named context property of a Log Event and returns every whole match of a regular expression in that value. Use it when the value you want is part of a context property, such as the file name at the end of a full file path.

  • ✅ Reads one of the context properties, chosen by its key
  • ✅ Returns the whole match; the message body is never read

When to use it

Four RegEx plugins cover the combinations of where the text is and what part of the match you want. For every plugin, see Choose a plugin.

Your data You want Use
Message body The whole match RegEx
Message body Only the part inside a capturing group ( ) RegEx with capturing groups
One context value (you know the key) The whole match RegEx on Message Context (this page)
One context value (you know the key) Only the part inside a capturing group RegEx on Message Context with capturing groups
One context value (you know the key) The value as it is, no pattern Message Context Key
XML stored in a context value An XPath result XPath on Message Context

Expression syntax

Select RegEx on Message Context in the Type list. The plugin shows two fields:

Type list open with the Expression Types, among them RegEx on Message Context (7.12)
The RegEx on Message Context plugin in the Type list.

Field What goes in it
RegEx The regular expression to run on the context value. The help text under the field ends with "The pattern ignores case and white space: write a space as \s or [ ] and # as \# (an unescaped # starts a comment)."
Context key The key of the context property to read. The key is case-sensitive: filename doesn't find FileName.
  • The result is the whole match. To return only a capturing group, use RegEx on Message Context with capturing groups.
  • Matching ignores case. Spaces in the pattern are ignored, and # starts a comment: write a literal space as \s or [ ], and a literal # as \#.
  • Each value is trimmed of leading and trailing white space, and an empty match is dropped. A pattern may run for 30 seconds per event at most.
  • Write the key exactly as it's logged. BizTalk context properties are logged as namespace#property, for example http://schemas.microsoft.com/BizTalk/2003/file-properties#ReceivedFileName.
  • Context properties and the reserved keys are described in Context Options. Properties that the ContextPropertiesFilters System Parameter removes aren't kept, so don't base a Search Field on them.

Expressions tab with Type RegEx on Message Context and the help texts under RegEx and Context key (7.12)
The plugin's fields with their help texts.

  • To test, add the key and its value on the Message Context tab of Test Expression. When the key is missing or nothing matches, the test reports Processed with warning: The Expression yields no result:

Test Expression result: Processed with warning, The Expression yields no result (7.12)
Test result when the key is missing or the pattern matches nothing in its value.

RegEx on Message Context with capturing groups returns ORD-10009 from the FileName context value, animated walkthrough (7.12)
Animated walkthrough: the sibling plugin RegEx on Message Context with capturing groups reads the FileName context value of a logged order confirmation and returns group 1, ORD-10009. With this plugin, the same pattern would return the whole match ORD-10009-.

Configure and test the expression as described in Add or manage Search Field and Test Your Expression.

Examples

Example 1: Extract the file name from a file path

Input

Key Value
FileName \\nodinitesrv01\ftp\public\INT001\Order\OrderFile_123.xml

Expression

  • RegEx:

    ([^\\]+$)

  • Context key: FileName

Result 

OrderFile_123.xml

[^\\]+$ matches the characters after the last backslash, up to the end of the value.

Test Expression for RegEx on Message Context returning OrderFile_123.xml from the FileName context key (7.12)
Test Expression: the file name extracted from the FileName context value on the Message Context tab.

Example 2: Extract the file name that BizTalk received

Input

Key Value
http://schemas.microsoft.com/BizTalk/2003/file-properties#ReceivedFileName C:\Integration\In\Orders\PO_4711.xml

Expression

  • RegEx:

    ([^\\]+$)

  • Context key: http://schemas.microsoft.com/BizTalk/2003/file-properties#ReceivedFileName

Result 

PO_4711.xml

To get only the order number 4711, use PO_(\d+)\.xml with RegEx on Message Context with capturing groups.

RegEx on Message Context test: a pattern for the text after the last backslash, on the ReceivedFileName key, returns PO_4711.xml (7.12)
The pattern keeps everything after the last backslash: the file name.

Next Steps