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Struts ActionForms |
ActionForms should not contain business objects because it binds the presentation layer to the model in the business tier. If the model changes, the presentation layer will have to change. Also, the business object should represent the native data types, such as int or Date, and for the purposes of user friendly validations, the web client is should be String-based and can only handle String or boolean data types without a conversion. Also, nesting a mutable business object does not work well if the business object rejects badly formatted data.so that the user's bad data can be displayed for correction.
If the business object is to be used for display purposes only, it should be accessed via a request or session attribute and not via an ActionForm variable. See the section on Actions for a description of how a request attribute can be set. See the section on JSPs for a description of how to access the request attribute.(What we use to advocate - to be corrected soon..._you can stuff biz objects directly into an ActionForm (and not flatten them out; i.e. you don't need to create fields in the form for each field in the biz object). Struts is able to deal with populating and returning nested objects. For example, you might have a "customer" bean on your ActionForm,_ and then refer to the property "customer.name" in your presentation page. This would correspond to the methods customer.getName() and customer.setName(String Name) on your customer bean. See the Apache Struts Taglib Developer Guides for more about using the nested syntax.)
ActionForms can be stored in either the request (preferable) or session (default) scope. This is configured in struts-config.xml. If they're in the session scope it's important to implement the form's reset method to initialize the form before each use (see mortar's reset method within ActionForm, SearchHelpParamsForm). ActionForms should be request scope unless they are carried across more than one page, as is the case for our mortar ActionForm, SearchHelpParamsForm, used in all or our OAS apps which implement search help with action path /SearchHelpNavAction (see struts-config). ActionForms associated with pages that have a search help icon need to be session scope. Otherwise, ActionForms should be request scope.
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