When should I query from a database in my view, ASP.NET MVC

Question

Problem:

If I have a scenario where I don't want to change my model properties and need to get one more attribute from some table, is it fine if I write a query inside a view and show the result?

If the answer is no, I would like to know why it's not considered a good way.

Why not query in the controller and put the data in ViewBag, or ViewData. Because regarding MVC principle you must separate concern of the View, Model and the Controller — user3383479
– user3383479, Commented Apr 15, 2014 at 9:52

Patrick Hofman · Accepted Answer · 2014-04-15 10:11:29Z

5

In my opinion you should never do that. Just because you loose the entire paradigm of the tool you are using.

In a few years, this is confusing to you, or someone else maintaining the code. If you don't want to change it all, use dynamic properties, ViewBag or other options to keep your flexibility, test-ability, etc.

answered Apr 15, 2014 at 10:11

Patrick Hofman

158k23 gold badges270 silver badges343 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Peter Mortensen · Accepted Answer · 2015-11-23 18:31:58Z

3

Yes.

View is not a mirror of your data structure. Actually, often it's an aggregation and/or manipulation for user-friendly presentation of the data that stands behind.

edited Nov 23, 2015 at 18:31

Peter Mortensen

31.4k22 gold badges110 silver badges134 bronze badges

answered Apr 15, 2014 at 9:43

Tigran

62.3k8 gold badges90 silver badges124 bronze badges

6 Comments

Laurent S. Over a year ago

But shouldn't all the data stand behind then ? Meaning that if you change your datamodel, you should adapt your model accordingly ? Innocent question, still discovering MVC myself... but putting database queries in a view seems in contradiction to the MVC principles... no ?

Tigran Over a year ago

You change Model to meet data changes, but you may not change a View. And vice versa. I can change View of the data, for newer UI, new control introduced, new set of screens has to be supported...etc, but the data remains the same.

Ehsan Sajjad Over a year ago

but there is some scenario where i want to check some condition based on db result that this particular element to be rendered or not, then what should be done?

Tigran Over a year ago

@EhsanSajjad: there are no rigid rules on this. you can do it in view, or in controller. it depends on who is processing the data in your architecture.

Tigran Over a year ago

@Bartdude: again, it depends. If he has a constrain of not changing a model to meet new requirements, for some reason. View may become a suitable layer, were you if/else data and send to client html based on some condition

|

Peter Mortensen · Accepted Answer · 2015-11-23 18:38:15Z

3

In my opinion, you should never do queries in your Views. It's called MVC and the proper way of using it is to separate concepts.

You should have a Model, a Controller, a View and a Repository (as the simpliest approach). As the name suggests, View must be used only for displaying processed data.

More information about MVC best practices is here.

I remember when I started working with MVC. I didn't know about this and my teamleader told me it's never a good choice to do this.

Conclusion:

It's just a matter of design and perspective. If you're doing a project for yourself or for the university, organize your code as you wish. If you're working in a professional environment you should respect some working principles

Another important factor to think of, is this: if another person must refactor or modify your code he must know where to find methods, where to find models and so on.

edited Nov 23, 2015 at 18:38

Peter Mortensen

31.4k22 gold badges110 silver badges134 bronze badges

answered Apr 15, 2014 at 14:17

Cosmin

2,2141 gold badge23 silver badges39 bronze badges

2 Comments

Cosmin Over a year ago

Thank you. I've updated the answer ( fixed some grammar problems :) )

Ehsan Sajjad Over a year ago

i accepted @Tigran answer as he answered good in a single sentence. but yoyrs was also good one thats why i voted up..:)

Xtian · Accepted Answer · 2014-04-16 06:19:41Z

2

First of all, the reason why it's called MVC is because of the separation of concerns. View's are only concerned of the User-Interface. Queries are done on the controller. Another is it would be too confusing if you would place everything in a single page which already defeats the purpose of having MVC.

answered Apr 16, 2014 at 6:19

Xtian

4982 silver badges6 bronze badges

Comments

Peter Mortensen · Accepted Answer · 2015-11-23 18:40:41Z

1

Though there are cases when querying the database from a View may seem easier and appropriate, you should be ready for the consequences of breaking separation of concerns (SoC). When you spread your DAL across many layers it's going to be hard to re-factor the database in the future. Another question is security - if you decide to implement database security or controller-based security later, your view-based queries will be a security point.

However, if the project is small, I would trade SoC for performance.

edited Nov 23, 2015 at 18:40

Peter Mortensen

31.4k22 gold badges110 silver badges134 bronze badges

answered Apr 15, 2014 at 10:05

d_z

7783 silver badges11 bronze badges

Collectives™ on Stack Overflow

When should I query from a database in my view, ASP.NET MVC

5 Answers 5

Comments

6 Comments

2 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

Comments

6 Comments

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related