Injecting data from HTML forms

Overview

HTML forms are an easy means of getting information from a user and they are also easy to create. Form data can be used for HTTP GET requests and HTTP POST requests:

GET: When form data is sent as part of an HTTP GET request the data is appended to the URI as a set of query parameters. Injecting data from query parameters is discussed in Using query parameters.
POST: When form data is sent as part of an HTTP POST request the data is placed in the HTTP message body. The form data can be handled using a regular entity parameter that supports the form data. It can also be handled by using the @FormParam annotation to extract the data and inject the pieces into resource method parameters.

Using the `@FormParam` annotation to inject form data

The javax.ws.rs.FormParam annotation extracts field values from form data and injects the value into resource method parameters. The annotation takes a single parameter that specifies the key of the field from which it extracts the values. The associated parameter must conform to the data types described in Supported data types.

	Important
	The JAX-RS API Javadoc states that the `@FormParam` annotation can be placed on fields, methods, and parameters. However, the `@FormParam` annotation is only meaningful when placed on resource method parameters.

Example

Example 3.8 shows a resource method that injects form data into its parameters. The method assumes that the client's form includes three fields—title, tags, and body—that contain string data.

Example 3.8. Injecting form data into resource method parameters

import javax.ws.rs.FormParam;
import javax.ws.rs.POST;

...
@POST
public boolean updatePost(@FormParam("title") String title,
                          @FormParam("tags") String tags,
                          @FormParam("body") String post)
{
  ...
}

Injecting data from HTML forms

Overview

Using the @FormParam annotation to inject form data

Example

Using the `@FormParam` annotation to inject form data