CODEWITHSUNDEEP
asp.net-mvcviewmodel
Dan
Dan

Reputation: 3258

View model design

I have a create page and an edit page for an entity. The pages are similar so I have a base view model which contains common fields between the pages, and a view model for each page which inherit from the base.

One of the differences between the two pages is that the create page has a search form where the user can enter criteria and search using an ajax query. The search criteria fields are not part of the entity. I created a "SearchCriteria" sub model with its own properties for the different search criteria so that I could simply post this model when performing the search, and potentially add more search criteria in the future without having to modify method parameters.

It turns out I do need to add something else, but that something else is one of the properties of the base view model. I'm not sure what the best way do this is. I'm thinking that I will have to consider the property to be no longer common and move it into my Edit view model and my SearchCriteria model, but then I lose my common mapping to the entity and will have to repeat code.

I think I may have gone wrong somewhere so some design advice would be appreciated.

Thanks

Upvotes: 1

Views: 228

Answers (1)

P.Brian.Mackey
P.Brian.Mackey

Reputation: 44275

I have faced a similar problem. First, with the search functionality. You can create a SearchServiceController. Then, add a partial view and pass it a model when you want to display the search bar, otherwise pass null and display nothing. This way you separate concerns by keeping the search functionality in its own process.

As far as adding a property that won't be used, I don't feel that this presents much of a problem. The .NET framework is filled with subclasses that do not implement parts of the base. Instead, you can throw a NotImplementedException. To me, its well worth the trade off to gain consistency and DRY.

Personally, I have found sharing viewmodels between controllers to not be a good thing (but in this case you may be using a single controller). Using IoC with Ninject, I get plenty of Cyclical Redundancy errors when binding my interfaces to the same viewmodels across controllers. For this reason, I took out Ninject. But, perhaps you can bind at another layer...have not tried it.

Upvotes: 1

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