<chapter id="_Form">
<title>@Form</title>

<para>

This is a RESTEasy specific annotation that allows you to re-use any @*Param annotation within an injected class.  RESTEasy will instantiate the class and inject values into any annotated @*Param or @Context property.  This is useful if you have a lot of parameters on your method and you want to condense them into a value object.
</para>
<para>

</para>
<para>

<programlisting>
public class MyForm {

    @FormParam("stuff")
    private int stuff;

    @HeaderParam("myHeader")
    private String header;

    @PathParam("foo")
    public void setFoo(String foo) {...}
}


@POST
@Path("/myservice")
public void post(@Form MyForm form) {...}
</programlisting>
</para>
<para>

When somebody posts to /myservice, RESTEasy will instantiate an instance of MyForm and inject the form parameter &quot;stuff&quot; into the &quot;stuff&quot; field, the header &quot;myheader&quot; into the header field, and call the setFoo method with the path param variable of &quot;foo&quot;.
</para>
<para>

</para>
<para>
Also, @Form has some expanded @FormParam features.  If you specify a prefix within the Form param, this will prepend a prefix to any form parameter lookup.  For example,
    let's say you have one Address class, but want to reference invoice and shipping addresses from the same set of form parameters:
</para>
<programlisting>
public static class Person
{
    @FormParam("name")
    private String name;

    @Form(prefix = "invoice")
    private Address invoice;

    @Form(prefix = "shipping")
    private Address shipping;
}

public static class Address
{
    @FormParam("street")
    private String street;
}

@Path("person")
public static class MyResource
{
    @POST
    @Produces(MediaType.TEXT_PLAIN)
    @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
    public String post(@Form Person p)
    {
        return p.toString();
    }
}
</programlisting>
    <para>
        In this example, the client could send the following form parameters:
    </para>
<programlisting>
name=bill
invoice.street=xxx
shipping.street=yyy
</programlisting>
    <para>
        The Person.invoice and Person.shipping fields would be populated appropriately. Also, prefix mappings also support lists and maps:
    </para>
<programlisting>
<![CDATA[public static class Person {
    @Form(prefix="telephoneNumbers") List<TelephoneNumber> telephoneNumbers;
    @Form(prefix="address") Map<String, Address> addresses;
}

public static class TelephoneNumber {
    @FormParam("countryCode") private String countryCode;
    @FormParam("number") private String number;
}

public static class Address {
    @FormParam("street") private String street;
    @FormParam("houseNumber") private String houseNumber;
}

@Path("person")
public static class MyResource {

    @POST
    @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
    public void post (@Form Person p) {} 
]]></programlisting>
    <para>The following form params could be submitted and the Person.telephoneNumbers and Person.addresses fields would be populated appropriately</para>
<programlisting>
request.addFormHeader("telephoneNumbers[0].countryCode", "31");
request.addFormHeader("telephoneNumbers[0].number", "0612345678");
request.addFormHeader("telephoneNumbers[1].countryCode", "91");
request.addFormHeader("telephoneNumbers[1].number", "9717738723");
request.addFormHeader("address[INVOICE].street", "Main Street");
request.addFormHeader("address[INVOICE].houseNumber", "2");
request.addFormHeader("address[SHIPPING].street", "Square One");
request.addFormHeader("address[SHIPPING].houseNumber", "13");
</programlisting>

</chapter>
