cfargument

Description

Creates a parameter definition within a component definition. Defines a function argument. Used within a cffunction tag.

Syntax

<cfargument  
    name="string"  
    default="default value"  
    displayname="descriptive name" 
    hint="extended description" 
    required="yes|no"  
    type="data type">

History

ColdFusion 10: Added the following REST attributes: restArgSource, restArgName

ColdFusion 8: Added component as a valid value for the ReturnType attribute.

ColdFusion MX 7: Added the xml value of type attribute.

ColdFusion MX: Added this tag.

Attributes

Attribute	Req/Opt	Default	Description
`name`	Required		String; an argument name.
`default`	Optional		If no argument is passed, specifies a default argument value.
`displayname`	Optional	`name` attribute value	Meaningful only for CFC method parameters. A value to display when using introspection to show information about the CFC.
`hint`	Optional		Meaningful only for CFC method parameters. Text to display when using introspection to show information about the CFC. The `hint` attribute value follows the `displayname` attribute value in the parameter description line. Use this attribute to describe the purpose of the parameter.
`required`	Optional	`no`	Note: All arguments are required when invoked as a web service, irrespective of how they are defined. Specifies whether the parameter is required to execute the component method. The parameter is not required if you specify a `default` attribute. `yes` `no`
`restArgSource`	Optional		One of the following: `path`: Extracts parameters from the resource URL. URI path parameters are extracted from the request URI, and the parameter names correspond to the URI path template variable names specified in the `restPath` specified in `cffunction`. The default value cannot be used with path param. `query`: Extracts parameters from URL query parameters. Mostly used with HTTP `GET` method. When using `GET` method to send data, the parameters and values are encoded into the URL. `QueryParam` is used to extract these values and assign them to the appropriate variables. `form`: Extracts parameters from a form submission. It is used with HTTP `POST` method. `cookie`: Extracts values form a cookie. `header:` Extracts parameters from HTTP header. `matrix:` Extracts parameters from matrix URI. For details, see http://www.w3.org/DesignIssues/MatrixURIs.html. If no value is specified, parameters are taken from the body of the request. Using `cfhttp`, you can send arguments in either form or body. For form parameter, the argument is consumed if you specify form as the value for `restArgSource` and for body parameter, if you do not specify `restArgSource`. While calling the service, if you pass the argument in body, in some scenarios, it is accepted as form. For example, `<cfhttpparam type="body" value="arg=somevalue">.` This is because, when you pass the form name-value pair through `cfhttp` or the body as `"name=value"`, the body content is same, due to which REST service is not able to detect what is passed. In the service, if you expect body argument but while accessing the service through `cfhttp`, no argument in the body is passed, you will still receive the body argument as empty string. If you use this attribute, but do not specify the type attribute, string is considered by default as the type.
`restArgName`	Optional		The name that can be mapped to the argument name. While calling functions, arguments are extracted from the incoming request. If `restArgName` is provided, it is searched in the `restArgSource` scope of the request to populate the argument. If not specified, argument name is searched. If specified, then argument name has no impact. You can specify correct argument name so that it corresponds to the appropriate parameter. If the argument name passed to a REST service is not a valid Java identifier, for example, the name has hyphen (say `arg-name`), then you can use this attribute to map the argument name.
`type`	Optional	`any`	String; a type name; data type of the argument. `any` `array` `binary` `boolean` `component`: the argument must be a ColdFusion component. `date` `guid`: the argument must be a UUID or GUID of the form xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx where each x is a character representing a hexadecimal number (0-9A-F). `numeric` `query` `string` `struct` `uuid`: the argument must be a ColdFusion UUID of the form xxxxxxxx-xxxx-xxxx-xxxxxxxxxxxxxxxx where each x is a character representing a hexadecimal number (0-9A-F). `variableName`: a string formatted according to ColdFusion variable naming conventions. `xml`: XML objects and XML strings a component name: if the type attribute value is not one of the preceding items, ColdFusion treats it as the name of a ColdFusion component. When the function executes, it generates an error if the argument that is passed in is not a CFC with the specified name.

Usage

This tag must be in a cffunction tag, before any other tags in the cffunction tag body.

Arguments that are passed when a method is invoked can be accessed from the method body in the following ways:

With shorthand syntax: #myargument#

(This example accesses the argument myargument.)
Using the arguments scope as an array: #arguments[1]#

(This example accesses the first defined argument in the cffunction.)
Using the arguments scope as a struct: #arguments.myargument#

(This example accesses the argument myargument in the array.)

Example

<!--- This example defines a function that takes a course number parameter and returns the course description. ---> 
<cffunction name="getDescription"> 
    <!--- Identify argument. ---> 
    <cfargument name="Course_Number" type="numeric" required="true"> 
    <!--- Use the argument to get a course description from the database. ---> 
    <cfquery name="Description" datasource="cfdocexamples"> 
        SELECT Descript 
        FROM Courses 
        WHERE Number = '#Course_Number#' 
    </cfquery> 
    <!--- Specify the variable that the function returns. ---> 
    <cfreturn Description.Descript> 
</cffunction>