====Parameter Filters====

You can use //parameter filters// to control which specific values are permitted when calling ARDI functions.

To specify a parameter filter, use the property name **param_**, plus the name of the parameter you want to filter. This should contain a regular expression used to match against the value sent by the user.

For example, let's say you want to open a URL so that an automated system can write a status to ARDI. This system is very simple and can't go through the normal ARDI API authentication flow.

<code javascript>
{
   "paths": {
	"api/asset/set": "specialwriter"
   },
   "groups": {
       "specialwriter": [[{
	    "type": "open"
	  }]],
          [{
	    "type": "whitelist",
	    "list": ["127.0.0.1","localhost"],
	    "param_property": "28",
	    "elevate": "editor"
	  }],
    }
}
</code>

This security rule does two things.

1) It allows normal access (the 'open' option) to any user who could normally access it, and \\
2) For **local** traffic, it allows write access to the endpoint, but **only if the 'property' parameter is 28**.

===Regular Expressions===

You can use //regular expressions// to allow specific formats or multiple different values to be allowed.

You can also combine multiple filters.

<code javascript>
{
   "paths": {
	"api/asset/set": "specialwriter"
   },
   "groups": {
       "specialwriter": [[{
	    "type": "open"
	  }]],
          [{
	    "type": "whitelist",
	    "list": ["127.0.0.1","localhost"],
	    "param_property": "(28|35)",
            "param_id": "(115|116)",
	    "elevate": "editor"
	  }],
    }
}
</code>

In the example above, the local machine can write to property 28 **or** 35, but only on asset 115 or 116.