How to access URL template parameters from "context.Request.MatchedParameters" object in Azure API Policy?

URL template parameters are parameters used in the URL defined in the URL template: For example, the following URL template contains two template parameters, "cid", "oid" and "date":

/customers/{cid}/orders/{oid}/?date={date}

When a client system calls this API service operation, it will provide actually values to template parameters. For example:

/customers/101/orders/999/?date=today

Azure API will store template parameters and values in the "context.Request.MatchedParameters" object for you to access. This "context.Request.MatchedParameters" is of the type, "IReadOnlyDictionary".

There are several ways to access template parameters and values:

1. Access it using the array syntax - If you know the parameter name, you access its value using the array syntax. For example:

    context.Request.MatchedParameters["parameter_name"]
    context.Request.MatchedParameters["cid"]
    context.Request.MatchedParameters["oid"]
    context.Request.MatchedParameters["date"]

2. Loop through the enumerator with correct type casted - If you don't know the parameter name, you loop through the key value pairs, with each item properly type casted. For example:

    IReadOnlyDictionary<string, string> dict context.Request.MatchedParameters
    foreach (KeyValuePair<string, string> item in dict) {
         MatchedParameters['"+item.Key+"']: "+item.Value;
    }

3. Loop through the enumerator with no type casting - If you don't know the parameter name, you loop through the key value pairs with no type casting. This format works better in Azure API management. For example:

    var dict context.Request.MatchedParameters
    foreach (var item in dict) {
         MatchedParameters['"+item.Key+"']: "+item.Value;
    }

For more information on the built-in "context" object, see API Management policy expressions Website.

⇒ 'context.Request.Url.Query' Query String Parameters

⇐ Using the 'context' Object in Policy Expressions

⇑ Using Azure API Policy

⇑⇑ Microsoft Azure API Management Tutorials