Question re. ch13-bankapp example and @ModelAttribute annotated methods

[Suresh M]

Hi,

Hope someone can help with this:

In chapter 13 Validation and Data Binding in Spring MVC, in example ch13-bankapp if I run the following test:

1. see the list of deposits

2. Click "Create New Fixed Deposit"

3. Enter deposit details and click "Save"

then I get the following console messages:

A - getNewFixedDepositDetails() method: Returning a new instance of FixedDepositDetails
B- openFixedDeposit() method: Fixed deposit details successfully saved. Redirecting to show the list of fixed deposits
... 2 more messages

Console messages A and B show that on clicking "Save", the getNewFixedDepositDetails() method populates an object called "newFixedDepositDetails" into the Model object, and then immediately afterwards the openFixedDeposit() method runs and
uses the @ModelAttribute argument annotation to get the "newFixedDepositDetails" object from the Model and put it into an object called fixedDepositDetails.

Question: why doesn't the "newFixedDepositDetails" object retrieved from the Model by openFixedDeposit() contain the dummy data "newFixedDepositDetails" created by the previously called getNewFixedDepositDetails() ?

I would imagine that when you click "Save", the browser returns data to the server, and the instance of "newFixedDepositDetails" Model attribute that contains user-entered data is overwritten by "newFixedDepositDetails" written by getNewFixedDepositDetails() ?

Clearly the software works as intended, so I have to assume that getNewFixedDepositDetails() does not write "newFixedDepositDetails" to the Model if the Model already contains an attribute called "newFixedDepositDetails". Is this correct?

Thank you.

[Suresh M]

ok, I think what's happening (?) is:

when you click "Save" on the New Deposit web page:

• the getNewFixedDepositDetails() method runs and puts an object called "newFixedDepositDetails" with initial data ("enter a valid email" etc) into the Model object,
• the openFixedDeposit() method runs and binds request parameters to the fields of the "newFixedDepositDetails" Model attribute created in getNewFixedDepositDetails().

[Ashish Sarin]

Your understanding is right. The openFixedDeposit method is called immediately after the getNewFixedDepositDetails method. 

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