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Skyhigh Security

Substitution and Placeholders

To allow more flexibility in retrieving external list data, placeholders can be used when configuring the settings of the External Lists module, for example, in URLs.

A placeholder is substituted at run time with a value that you provide as a parameter of an external list property.

For example, you want to retrieve data from a web service that delivers lists of media types allowed for individual users. A URL for a particular media type list would then be:

http://my-web-service.com/ mediatypes?user= <value>

where <value> is the name of a user.

Configuring separate settings for the External Lists module to cover each user individually would be tiresome, so you can use a placeholder in the following way:

  • For the Web service’s URL parameter in the settings, you specify:

    http://my-web-service.com/mediatypes?user=${0}

    where ${0} is a placeholder for the first of the three parameters of the external list property you are using in a rule.
     
  • For the first parameter of the external list property, you specify the Authentication.Username property.

This retrieves a list with the media types that are allowed for an individual user. The user name is the one that this user submitted when required to authenticate after sending a request to access media of a particular type.

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