great thanks!!!
tibi
Dustin Pearce wrote:
> When you want to modify just a "part" of an object, you need to be
> sure that you load the model from the database *before* you apply the
> parameters posted from your web form. What is happening is that your
> form is creating a *new* user instance and populating the fields from
> your small form (id, name, etc) and then updating the database.
>
> Typically, this is done using the Preparable interface on your action
> in Struts. In prepare() you look for the id of the object and you
> try and load it from the database. The tricky part has to do with
> Struts2 interceptors. The two interceptors we are concerned with are
> params and prepare. If you look at struts.xml you will see a list of
> interceptors defined as a "stack". In this list you will see prepare
> and then you will see params later on. The prepare interceptor checks
> to see if your object implements Preparable and calls prepare() if it
> does. The param interceptor takes the parameters posted in the
> request and applies them to the various setters on your action. What
> makes this tricky is that we have a setter called setId() that we need
> to be called *before* prepare in order to know what object to load.
> The solution is to add another reference to params interceptor before
> prepare. The net effect is that Struts will apply all the parameters
> from your post, then call prepare and load the object from the
> database (overwriting the post values), and then Struts will write the
> post values again, only overwriting what you have posted and keeping
> the older values from the database. In this example you can also look
> for user.getId() in prepare, but you'd have to check to see if user is
> null.
>
> So that is how it was done in Struts for thousands of years. Now in
> the lastest versions of Appfuse, Matt has come with a rather nice
> solution using prepare. In his example you don't need to add the
> extra run of the params interceptor before prepare because he works on
> the raw request. This is some nice code, that gets around a rather
> painful pattern in Struts. The only complaint I would have is making
> your action http dependent. Its is considered bad form to have your
> action work with HTTP elements like HttpServletRequest or
> HttpServletSesssion directly. There are plans to correct this in the
> near future by using Struts built in support like RequestAware or
> SessionAware that return a plain map connected by Struts to the HTTP
> object.
>
> public void prepare() {
> if (getRequest().getMethod().equalsIgnoreCase("post")) {
> // prevent failures on new
> if (!"".equals(getRequest().getParameter("user.id"))) {
> user =
> userManager.getUser(getRequest().getParameter("user.id"));
> }
> }
> }
>
>
> So the moral is follow Matt's pattern. Unless you plan to submit
> EVERY SINGLE field for a model when you save or update then its a good
> idea to get this prepare() pattern to be part of your muscle memory. ;-)
>
>
>
>
>
>
> On Apr 1, 2008, at 3:12 AM, tibi wrote:
>
>> hi list,
>>
>> im not sure how to update an user when i only want to update one or two
>> fields.
>> using struts spring hibernate
>>
>> lets say i only want to change the name.
>> i make a form with hidden field with id and a normal field with name.
>>
>> when i enter my save method i have a user with only an id and name. and
>> the other fields like password version etc. are empty.
>>
>> should i get the old userfrom the db and copy the name from the new one
>> to the old one and update it??
>> should i put all fields hidden in my form?
>> should i save the user into the session?
>>
>> thanks,
>>
>> tibi
>>
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