Tools, FAQ, Tutorials:
'@(...)' Expressions in Azure API Policy
How to use the "@(...)" expression in Azure API Policy?
✍: FYIcenter.com
The "@(...)" expression in Azure API Policy can be used
to include a single C# expression as the attribute value or text value in most policy statements.
When a "@(...)" expression is included in a policy statement, the C# expression will be evaluated first and the result of the evaluation will be used in the policy statement.
For example, the following "set-variable" policy statement uses a "@(...)" expression as an attribute value to set a new variable to be used later:
<set-variable name="isMobile" value="@(Context.Request.Headers["User-Agent"].Contains("iPhone"))" />
The following "trace" policy statements uses a "@(...)" expression as a text content to verify some properties from the built-in "Context" object:
<trace source="MyDebug">@("I am here!")</trace> <trace source="MyDebug">@(context.Request.Url.Path)</trace> <trace source="MyDebug">@(context.Request.MatchedParameters["id"])</trace>
Note that the C# expression inside "@(...)" must be XML friendly. For example, the "<" sign should be replaced with <. But Azure takes the "<" sign too without any trouble:
<trace source="MyDebug">@( 1 < 2 )</trace> <trace source="MyDebug">@( 1 < 2 )</trace>
Also note that the "@(...)" expression can not be mixed with text as attribute values or text contents. The following examples are wrong uses of "@(...)" expressions:
<set-variable name="message" value="Hello @("world!")" /> <trace source="MyDebug">Hello @("world!")</trace> <trace source="MyDebug">@("Hello") world!</trace>
For more information on "@(...)" expressions, see API Management policy expressions Website.
2018-02-14, 4481🔥, 0💬
Popular Posts:
How to use 'choose ... when ..." policy statements to control execution flows? If you want to contro...
How to Install Docker Desktop on Windows 10? You can follow this tutorial to Install Docker Desktop ...
How to use the XML to JSON Conversion Tool at freeformatter.com? If you want to try the XML to JSON ...
FYIcenter JSON Validator and Formatter is an online tool that checks for syntax errors of JSON text ...
How to run PowerShell Commands in Dockerfile to change Windows Docker images? When building a new Wi...