ASP.net MVC dynamically alter database structure and update model - asp.net-mvc

I am in phase of designing architecture of my web application. I want to work with asp.net mvc5 and oracle database at back end.
One basic requirement of my project is that the application's admin users can add/remove Form Fields. I want to physically add/remove columns in my database tables at run time (not design time).
How can I achieve it in mvc and how the models can be updated dynamically at run time?
Should I use some ORM or how I design data access layer for that?
I just need suggestions and hints for the architecture design approaches.

Instead of physically adding and removing the fields at runtime you can try the following table structure
Field Name Field Type
CustomField1Name Nvarchar(256)
CustomField1Value Nvarchar(Max)
CustomField1IsVisible Bool
CustomField1FieldType Nvarchar(32) [char/numeric/bool etc]
CustomField1Required Bool
CustomField2Name Nvarchar(256)
CustomField2Value Nvarchar(Max)
CustomField2IsVisible Bool
CustomField2FieldType Nvarchar(32)
CustomField2Required Bool
If you need any more field specific information like custom validation you can add here.
Repeat this for how many custom fields you want . Due to this design, in run time there will be no structure changes in DB level. All changes you can do in coding level.

Entity attribute value pattern is one way to go. In my opinion this becomes an anti-pattern if overused. This has some shortcomings such as storing every value as a string. You might find it hard to parse "true+" as a bool. You could also do this in a weakly typed fashion or weakly typed datasets. If you want to go this route you would actually be creating columns. Do not give users rights to create columns, give them rights to execute a proc that creates columns.

Related

MVC Model required field, sometimes

I am trying to reuse my model in my MVC project. However in some instances the model needs to have all its fields filled and in others only some fields need to be filled. I applied [Required] attribute to fields that are required in all cases. But what about others? Is there a way to make those other fields required in just certain instances?
Thanks for any ideas.
You could do it a "hacky" kind of way by creating a custom validator that you trigger with, say, another field in the model. But that seems odd. I'd really opt for having a custom VM for each of the cases: one where required, one where not. You can then use one of many tools to map from your VM to your Model if you're concerned with having to copy fields over. Look at Automapper and ServiceStack.Text (which has a TranslateTo method) for two examples of simple mappers.

MVC 4 Strongly Typed Data to View without ORM

I've seen other questions regarding using straight SQL for MVC data access, for example here. Most responses don't answer the question but ask
"Why would you not want to use ORM, EF, Linq, etc?"
My group does custom reporting out of a data warehouse that requires a lot of complex, highly tuned Oracle queries that are manipulated based on user GUI parameter selections.
My newest project is to develop a SQL plugin reporting tool for SQL report developers. They would create a pre-tuned SQL for the report with pseudo parameters and enter (and store) via the GUI. Then the GUI would prompt them for the parameter definitions (name and type) that need to be displayed/requested at run time to ultimately replace the pseudo variables.
So a SQL statement may look like:
SELECT * FROM orders WHERE order date BETWEEN '<Date1>' AND '<Date2>'
And the report developer would then, via the GUI, add two parameters named Date1 and Date2, and flag them as date fields.
End users would then select the report, get prompted for Date1 and Date2, and the GUI would do the substitution and run the SQL.
As you can see, I have no choice but to use straight SQL (especially in the 2nd example and understand I would have to forgo strongly typed in the 2nd also).
So my questions are:
When is it necessary to bypass EF/Linq (and there are definitely reasons to), what is best practice in MVC 4?
And how best to strongly type when I do know the output columns ahead of time?
And CRUD processing?
Can anyone point me to any examples of non-EF/Linq based coding in this regard?
I think this is a bit open ended question, so here's my 2c. (If tl dr, go to last section)
To me, it's not so much "by passing EF/Linq", but rather, the need to choose the appropriate data persistence library. I have used PetaPoco, Ado.Net, NHibernate/ActiveRecord, Linq2Sql, EF (My main choice) with MVC.
Best practice actually comes from realising that Controllers are STILL a part of presentation layer, and that it should not deal with anything other than HttpContext related operations + calling business logic service classes.
I arrange my classes as:
Presentation (MVC) -> Logic Services (Simple classes) -> Data Access (Context wrapped in "repositories").
So I can't quite imagine whether to use EF or not would have any implication on asp.net MVC.
For me, Data Access returns data in DTO, e.g.
public List GetAllFoos()
Whether that method string concatenate from a xml, etc or do a simple Context.Foos.ToList() is irrelevant to the rest of the application. All I care is Data Access do NOT return me a DataSet with string matching for columns. Those stay in DAL.
See point 1 and 2. My repositories have CRUD methods on it. How it's done is irrelevant to the rest of application. Take one of the most basic interface to my repositories classes:
public interface IFooRepository
{
void Save(Foo foo)
Foo Get(int id)
void Create(Foo foo)
void Delete(int id)
}
One point not mentioned yet, DI is also crucial. The concrete implimentation "FooRepository" may choose to request dependencies such as Web services, context classes, etc. Those are, however, again, completely irrelevant to the caller who depends on the interface.
If you still require an example after the 3 points above, drop a comment and I'll whip up something extremely simple using Ado.net.
===========================================================================
To EF or not to EF.
For me, if starting a new project with new schema, I use EF code first.
Fitting new code to old database + old project has no ORM mapping I can reuse = PetaPoco.
===========================================================================
In the context of your project:
The "SQL plugin reporting tool for SQL report developers". "The" sql reporting service? I'm not sure why you need to do anything? Doesn't SSRS already do that? (Enter sql statement/data source, generate form for parameter, etc).
If not I'd question the design decision. IMVHO, the need for users of an application (I don't care if it's "report developer" or w/e) to enter SQL statements is usually stemmed from "architectural astronauts". How do you debug the SQL statement when you enter via GUI as a string? How do you know the tables and the relationships? You either dig into SSMS and come back to gui, or you build complex UI (aka rebuild SSMS).
At the end of day, if you want bazillion reports for gazillion different users, you have to pay for it. I see too many "architectural astronauts" who exposes application to accept SQL statements only to make everyone waste time guessing what should be put into it. No cost saving at all.
Ok, if you must do that, well eh... Good luck. Best bet is to return as a DataTable and dump the rows/columns/data on to the view with nested foreach looping through rows then columns.

Are there Visual Studio Tools For Creating DTO/ViewModel

I'm trying to introduce ASP.Net MVC to my department. I am encouraging them to have a ViewModel per View and AutoMapper for our larger projects (and ideally in general).
Sometimes this means having one large entity and picking 5 of its properties and creating the ViewModel. This is done by looking at the the edmx model (many projects were existing so it was DB first) and then creating matching properties in a ViewModel class. Obviously names etc have to match for AutoMapper to work. Also for navigation properties you have to add the navigation name first. Ideally also being able to type in a display name etc.
I'm trying to ease them into doing this (what they see as extra work). Is there any tool that would load a list of fields and allow you to select via checkbox etc and create the class from that?
I guess the same would apply to DTOs etc
Thanks
Have you tried this http://www.codesmithtools.com/product/generator
you can create a template of the dto and then it will generate the files/dto's for you as needed from any kind of datasource.

NHibernate - Updating only specified object properties identified at runtime

I'm trying to implement a very granular security module in an ASP.NET MVC 3 app where only certain users can edit certain columns on records in a table. I can imagine that the update SQL statement's list of columns would only include the columns that the user had the right to change. The thing is, I'm planning to use an ORM like NHibernate. I'm wondering if NHibernate provides a way to determine at runtime which properties of a model should be part of an Update. Or is my only option to, on the POST method, get the model again from the database, set only the properties that the user is allowed to set then finally Save the model. Also, is this a good way to handle my requirement of of granular security?
Would dynamic-update and dynamic-insert be enough?
dynamic-update (optional, defaults to false): Specifies that UPDATE SQL should be generated at runtime and contain only those columns whose values have changed.
dynamic-insert (optional, defaults to false): Specifies that INSERT SQL should be generated at runtime and contain only the columns whose values are not null.
Otherwise it might be possible with events or interceptors, but I've never used them so I don't know exactly.

Model binding to DataTable with no underlying database

I am bootstrapping myself through my very first ASP MVC project, and could use some suggestions regarding the most appropriate (data-side) model binding solution I should pursue. The project is 'small', which really just means I have very limited time for chasing down dead-ends, which cramps my available learning curve. Thanks heaps for reading!
Background: a simple address search app (ASP.NET MVC 3) that sends user form input to a vendor-sourced server, and presents the results returned from the server in a rules-driven format. There is no CRUD-style repository as such; this is an entirely read-only application. The vendor's .NET server API specifies the use DataTable objects (System.Data.DataTable) for both requests and replies.
Currently: I have a prototype under construction to validate server behavior and inform the application's design. There is a conventional MVC data model class for the input form which works great, auto-binding with the view just as you'd expect. When submitted, the controller passes this input model to my vendor API wrapper, which is currently binding to the request table medieval-style:
public DataTable GetGlobalCandidateAddresses(AddressInputModel input)
{
...
DataRow newRow = dataTable.NewRow();
newRow[0] = input.AddressLine1;
newRow[1] = input.AddressLine2;
newRow[2] = input.AddressLine3;
...
dataTable.Rows.Add(newRow);
...
This works fine; the inputs are fixed and have very light validation requirements. However, if there is a modern framework solution for quickly reflecting a DataTable from my model, that would be peachy.
My real conundrum, however, is on the reply. The table returned by the server contains a variable column-set, with any combination of at least 32 possible unordered fields on a per-transaction basis. Some of the column names contain compiler-invalid characters ("status.description") that won't map literally to a model property name. I will also have a need to dynamically map or combine some of the reply fields in the view model, based on a series of rules (address formats vary considerably by country), so not all fields are 1-to-1.
Just to get the prototype fired up and running, I am currently passing the reply DataTable instance all the way back to a strongly-typed view, which spins it out into the display exactly as is. This is nice for quickly validating the server replies, but is not sufficient for the real app (much less satisfying best practices!).
Question: what is my best tooling approach for binding DataTable rows and columns into a proper model class for display in a view, including some custom binding rules, where no underlying database is present?
Virtually all of the training materials I am consuming discuss classic database repository scenarios. The OnModelCreating override available in the Entity Framework seems ideal in some respects, but can you use a DBContext without a DB connection or schema?
If I have to roll my own model binder, are there any tricks I should consider? I've been away from .NET for a while (mostly Java & SQL), so I'm picking up LINQ as I go as well as MVC.
Thanks again for your attention!
Create a poco display model AddressDisplay and do custom object mapping from the data table to the display model. You can use data annotations for formatting but you can also do that in your custom mapping. You shouldn't need to create a custom model binder.
So create two poco models, AddressInput and AddressDisplay, you can use data annotations on AddressInput for validation. When AddressInput is posted back, map it to the outbound data table. When the response is received, map the inbound data table to AddressDisplay and return the view to the user.

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