Databases
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PO
 

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    <p>They serve a similar purpose (encapsulating data for another layer of the application) but they do it differently and for different reasons.</p> <ul> <li><p>The purpose of a DTO is to reduce the number of calls between tiers of an application, especially when those calls are expensive (e.g. distributed systems). DTOs are almost always trivially serializable, and almost never contain any behaviour.</p> <p>For example, you're developing an e-Commerce site. <code>CreateCustomer</code> and <code>AddCustomerAddress</code> are separate operations at the database level, but you might for performance reasons want to aggregate their data into a <code>NewCustomerWithAddressDto</code> so that your client only needs to make one round-trip to the server, and doesn't need to care that the server might be doing a bunch of different things with the parcel of data.</p></li> <li><p>The term "ViewModel" means slightly different things in different flavours of MV*, but its purpose is mainly separation of concerns. Your Model is frequently optimised for some purpose other than presentation, and it's the responsibility of the ViewModel to decouple your View from the Model's implementation details. Additionally, most MV* patterns advise making your Views as "dumb" as possible, and so the ViewModel sometimes takes responsibility for presentation logic.</p> <p>For example, in the same e-Commerce application, your <code>CustomerModel</code> is the wrong "shape" for presentation on your "New Customer" View. For starters, your View has two form fields for your user to enter and confirm their password, and your <code>CustomerModel</code> doesn't contain a password field at all! Your <code>NewCustomerViewModel</code> will contain those fields and might, depending on your flavour of MV*, be responsible for some presentation logic (e.g. to show/hide parts of the view) and basic validation (e.g. ensuring that both password fields match).</p></li> </ul>
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    1. COThat's an excellent explanation! Up until now the only view models I had seen only had getters and setters so I was like: wow that's so much like a DTO. Thanks for clearing this up for me.
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Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

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