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POData binding of an abstract class in spring-mvc
 

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  1. POData binding of an abstract class in spring-mvc
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    <p>I've went thru Spring documentation and source code and still haven't found answer to my question.</p> <p>I have these classes in my domain model and want to use them as backing form objects in spring-mvc.</p> <pre><code> public abstract class Credentials { private Long id; .... } public class UserPasswordCredentials extends Credentials { private String username; private String password; .... } public class UserAccount { private Long id; private String name; private Credentials credentials; .... } </code></pre> <p>My controller:</p> <pre><code> @Controller public class UserAccountController { @RequestMapping(value = "/saveAccount", method = RequestMethod.POST) public @ResponseBody Long saveAccount(@Valid UserAccount account) { //persist in DB return account.id; } @RequestMapping(value = "/listAccounts", method = RequestMethod.GET) public String listAccounts() { //get all accounts from DB return "views/list_accounts"; } .... } </code></pre> <p>On UI I have dynamic form for the different credential types. My POST request usually looks like:</p> <pre><code> name name credentials_type user_name credentials.password password credentials.username username </code></pre> <p>Following exception is thrown if I try to submit request to the server :</p> <pre><code> org.springframework.beans.NullValueInNestedPathException: Invalid property 'credentials' of bean class [*.*.domain.UserAccount]: Could not instantiate property type [*.*.domain.Credentials] to auto-grow nested property path: java.lang.InstantiationException org.springframework.beans.BeanWrapperImpl.newValue(BeanWrapperImpl.java:628) </code></pre> <p>My initial thought was to use <code>@ModelAttribute</code></p> <pre><code> @ModelAttribute public PublisherAccount prepareUserAccountBean(@RequestParam("credentials_type") String credentialsType){ UserAccount userAccount = new PublisherAccount(); Class credClass = //figure out correct credentials class; userAccount.setCredentials(BeanUtils.instantiate(credClass)); return userAccount; } </code></pre> <p>Problem with this approach is that <code>prepareUserAccountBean</code> method get called before any other methods (like <code>listAccounts</code>) as well which is not appropriate.</p> <p>One robust solution is to move out both <code>prepareUserAccountBean</code> and <code>saveUserAccount</code> to the separate Controller. It doesn't sound right : I want all user-related operations to reside in the same controller class.</p> <p>Any simple solution? Can I utilize somehow DataBinder, PropertyEditor or WebArgumentResolver?</p> <p>Thank you!!!!!</p>
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    1. USJerome Dalbert
    1. USDenys K.
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    1. COCan you post the full code from your domain classes? I'd like to see your constructors.
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      1. POData binding of an abstract class in spring-mvc
      1. USRich Cowin
    2. COSounds to me like this is more of a mapping/serialization/conversion issue with your database than it is with the view. Are the accounts being correctly deserialized into the correct objects before being sent to the view?
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      1. USDavidA
 

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