I have found help for subclassing of a mapped superclass, and I have found help on how to map a TreeMap. However, I can not find anything that covers using a TreeMap in a subclass at all. Here is the situation: I am adding a function to a long-existing application. That application has mapped entities, a certain set of which, form a hierarchy. There is a , for instance that establishes the base class. Then there are many many MANY subclasses that use the elements to map the individual subclasses. The subclasses all use elements to reference the additional table that holds the attributes of the subclass. This has worked for several years and life has seemingly been good.
Now along comes my work effort and I need to use a TreeMap in my new subclass entity (extending the same base class as all of the others) so the first thing that I do is attempt to map it the same way other subclasses do, with a inside a .
Making the story short, I got an error when I started the app and Hibernate began mapping. Researching this error led me to review the DTD for hibernate mapping files and, guess what? According to my interpretation, one can not configure a Map of any kind inside a .
That same research exposed me to the which CAN contain a Map. So, off I go configuring a inside the base class mapping.
When I did this, I got bizarre errors referencing symbols that I can't even find in the code, in mappings.... anywhere! More research and I find a reference in the Hibernate reference manual, Chapter 9, that says that Hibernate does not support mixing of and elements. So that can't be done either.
My question is: is there a solution that I have missed along the way? From the sound of things it seems that you can NOT configure a map in a subclass if you are using because the inside it won't take a map.... and, while a Map can be configured in a , I doubt that I can gather up much support around here for wading through the current mapping files and re-mapping ALL entities as entities.
Has anybody got any ideas? If I am not looking at this right, believe me, I am willing to accept that and learn!
Related
I worked on DotNetNuke in some projects and I find very much interesting Custom Business Object Class which is named as CBO.vb in the DotNetNuke project.
So I want to use this helper class in my other project also which is not in DotNetNuke but in core asp.net projects.
So I read about some important methods of this class which are majority used by me are:
CBO.FillObject
FillCollection
Now I am searching what are issues in this class that can be improved by me before I am going to use this class.
So I search this and found an interesting topic on code project which point out several issues like:
business object and the fields in the database had to have the same name
FillCollection method returned an ArrayList
So my question is there any other thing which can be solved before use like
use reflection to create objects which are slower for that they give idea how to implement this by using The IHydratable Interface
You can find class here
CBO is a useful class. However if I were looking for a similar solution today, I would look to one of the new "Micro-ORMs" such as:
Massive
PetaPoco
Dapper
When applying such a light wrapper around the database, I am not sure that supporting different names in the DB and business objects is really a good idea. It is a likely source of confusion.
Also there are already generic overloads for the FillCollection method which return List<T>. The ArrayList versions are only there for backward compatibility, no one should write any new code with them.
In the recent spirit of isolating stuff and plugging it in via NuGet, does anyone have an idea about how you'd limit a dependency resolver to just one area in MVC3? It's easy enough to keep views and controllers limited to an area, but unless I'm not seeing an obvious hook, it looks like setting an IDependencyResolver is something that unavoidably has global scope. I'd like to limit it to just one area.
Any suggestions?
IDependencyResolver is global by design. If you want to vary behavior by area, you should look at the various *Activator types and interfaces that can make decisions based on context objects.
What specifically are you trying to do?
I would suggest using the Common Service Locator for this. Basically each area could setup up the CSL for their specific container.
You will probably need to create an adapter between the dependency resolver or forgo it altogether and strictly use the CSL.
In general I am not a proponent of using the CSL in a line of business app. It's intent is to make it easier for open source components that use DI (like MassTransit) easier to integrate into line of business apps. This might be an exception however.
Also, look into the mvccontrib portable areas. It's designed for this type of thing.
What you're trying to do sounds like a bad idea. The point of dependency injection is so you can isolate specific dependencies and not have your code care where they come from.
If you're trying to restrict some objects or classes to a certain MVC area, configure your dependency injector to call the proper ones at the right time.
Some more details about what you're trying to do will help generate better answers.
We're currently migrating our ASP Intranet to .NET and we started to develop this Intranet in one ASP.NET website. This, however, raised some problems regarding Visual Studio (performance, compile-time, ...).
Because our Intranet basically exists of modules, we want to seperate our project in subprojects in Visual Studio (each module is a subproject).
This raises also some problems because the modules have references to each other.
Module X uses Module Y and vice versa... (circular dependencies).
What's the best way to develop such an Intranet?
I'll will give an example because it's difficult to explain.
We have a module to maintain our employees. Each employee has different documents (a contract, documents created by the employee, ...).
All documents inside our Intranet our maintained by a document module.
The employee-module needs to reference the document-module.
What if in the future I need to reference the employee-module in the document-module?
What's the best way to solve this?
It sounds to me like you have two problems.
First you need to break the business orientated functionality of the system down into cohesive parts; in terms of Object Orientated design there's a few principles which you should be using to guide your thinking:
Common Reuse Principle
Common Closure Principle
The idea is that things which are closely related, to the extent that 'if one needs to be changed, they all are likely to need to be changed'.
Single Responsibility Principle
Don't try to have a component do to much.
I think you also need to look at you dependency structure more closely - as soon as you start getting circular references it's probably a sign that you haven't broken the various "things" apart correctly. Maybe you need to understand the problem domain more? It's a common problem - well, not so much a problem as simply a part of designing complex systems.
Once you get this sorted out it will make the second part much easier: system architecture and design.
Luckily there's already a lot of existing material on plugins, try searching by tag, e.g:
https://stackoverflow.com/questions/tagged/plugins+.net
https://stackoverflow.com/questions/tagged/plugins+architecture
Edit:
Assets is defined in a different module than employees. But the Assets-class defines a property 'AssignedTo' which is of the type 'Employee'. I've been breaking my head how to disconnect these two
There two parts to this, and you might want to look at using both:
Using a Common Layer containing simple data structures that all parts of the system can share.
Using Interfaces.
Common Layer / POCO's
POCO stands for "Plain Old CLR Objects", the idea is that POCO's are a simple data structures that you can use for exchanging information between layers - or in your case between modules that need to remain loosely Coupled. POCO's don't contain any business logic. Treat them like you'd treat the String or DateTime types.
So rather than referencing each other, the Asset and Employee classes reference the POCO's.
The idea is to define these in a common assembly that the rest of your application / modules can reference. The assembly which defines these needs to be devoid of unwanted dependencies - which should be easy enough.
Interfaces
This is pretty much the same, but instead of referring to a concrete object (like a POCO) you refer to an interface. These interfaces would be defined in a similar fashion to the POCO's described above (common assembly, no dependencies).
You'd then use a Factory to go and load up the concrete object at runtime. This is basically Dependency Inversion.
So rather than referencing each other, the Asset and Employee classes reference the interfaces, and concrete implementations are instantiated at runtime.
This article might be of assistance for both of the options above: An Introduction to Dependency Inversion
Edit:
I've got the following method GetAsset( int assetID ); In this method, the property asset.AssignedTo (type IAssignable) is filled in. How can I assign this properly?
This depends on where the logic sits, and how you want to architect things.
If you have a Business Logic (BL) Layer - which is mainly a comprehensive Domain Model (DM) (of which both Asset and Employee were members), then it's likely Assets and Members would know about each other, and when you did a call to populate the Asset you'd probably get the appropriate Employee data as well. In this case the BL / DM is asking for the data - not isolated Asset and Member classes.
In this case your "modules" would be another layer that was built on top of the BL / DM described above.
I variation on this is that inside GetAsset() you only get asset data, and atsome point after that you get the employee data separately. No matter how loosely you couple things there is going to have to be some point at which you define the connection between Asset and Employee, even if it's just in data.
This suggests some sort of Register Pattern, a place where "connections" are defined, and anytime you deal with a type which is 'IAssignable' you know you need to check the register for any possible assignments.
I would look into creating interfaces for your plug-ins that way you will be able to add new modules, and as long as they follow the interface specifications your projects will be able to call them without explicitly knowing anything about them.
We use this to create plug-ins for our application. Each plugin in encapsulated in user control that implements a specific interface, then we add new modules whenever we want, and because they are user controls we can store the path to the control in the database, and use load control to load them, and we use the interface to manipulate them, the page that loads them doesn't need to know anything about what they do.
I have a database I'd like to create an entity from, and then generate RESTful output.
My objective is to add a property to one of the tables once it becomes an entity. The data for that property would be one I'd come up with through calculations done on a few different fields in the table. From there, the code generator would create RESTful output like it normally does.
I have managed to be able to update the SSDL, CSDL, and the mapping sections of the edmx file along with using the SampleEdmxCodeGenerator as a custom tool. When I have all the sections in the edmx file filled out with my custom property, the svc fails because (I'm assuming) the property doesn't exist in the database. If I leave the property out of the SSDL, but put it in the client schema (CSDL) and the mapping section, I can't build my project.
I've modified the partial class and added to it, but the problem there is that I need to populate the methods on the creation time of the class, and I haven't been able to do that yet.
Am I headed in the right direction, or is this not possible? It seems like I should be able to do this with minimal effort, but I keep hitting walls.
I think you're taking detours to get where you want. I haven't used either of these approaches (recently), so they might not do exactly what you're after, but you could try this:
Create a partial class file right next to the .edmx model, which has the same name as your entity.
In it, specify the property you want as a read-only property, that does the calculations on each get.
Partial Classes and Partial methods were the first part of my answer. What I'm essentially trying to do I can't do. I can manipulate data that is returned by using partial methods and partial classes. I can plug the OnmethodnameChanged() method to format the data how I'd like it to be shown, but that only gets me part way to my desired result.
What I would also like to do, is create a property c, which doesn't exist as a column in the database (and therefore does not exist in my entity), calculated from a couple different properties in the database (say a and b), and then add property c to the entity framework class. In doing this, I figured it would then get generated into the RESTful webservice output.
A problem that occurs comes from the need for the class to update any changes you make, and have it propagate back to the data source. I didn't care about that, because I want my property to be read only. From what I've gathered this isn't possible.
For reference, these two posts really helped:
Adding custom property to Entity Framework class
(I can only post one url currently, so here is the address to the other article)
social.msdn.microsoft.com/Forums/en-US/adodotnetdataservices/thread/b7a9e01d-c5c2-4478-8f01-00f7f6e0f75f
What I've decided to do, is to expose my entity as I've done so far, then consume the RESTful service that manipulates data and reformats it, and introduces needed properties. I'll turn the results into my own data object, and use that as a datasource to be exposed by yet another RESTful web service. I think this website gives a good example on how to expose a custom datasource.
mstecharchitect.blogspot.com/2008/12/surfacing-custom-data-source-in-adonet.html
If for some reason that is too slow, I suppose I could just make another table in my database that has a reworking of the data, and the calculated output in a format I'm looking for. The thing I want to avoid is having my resulting client having to do any of the data manipulation since it will be on some micro devices like palms, iphones, and blackberries.
Hope that helps anyone else with the same problem. It seems that is a shortfall in the current version of Data Services, but to some extent, I'm sure they'll be addressing it in later versions. Maybe T4 and .net 4.0 will be addressing it. I'm not sure.
I was watching a tutorial on Rails and was very impressed that you could so easily create an editing system for a class just by defining it.
Can this be done in ASP.NET?
I know there are ORMs out there, but do they come with an editing system?
To explain what I mean by an editing system, consider a class for defining people
class Person
{
string First_Name;
string Last_Name
}
And then perhaps with one bold stroke something like this:
CreateEditAbleClass(Person)
You would get the functionality below in a browser:
http://www.yart.com.au/images/orm_editor.jpg
And this functionality would extend to all the UML definitions – inheritance, association, aggregation etc. In addition, there would be a simple way of adding customisable validation and so forth.
I currently use DataGrids and a lot of manual coding to achieve these results.
You can do it with reflection. Using reflection, you can enumerate over the members of a class, and therefore create a form to edit the members.
Creating the code for rendering the web form based on the members of the class is a bit more code then I'm willing to type out here, but if you look into reflection you should be able to come up with your own solution in a couple hours.
Sure. This is off the top of my head, but I believe you could connect your class to an ObjectDataSource component which would in turn connect to a DetailsView control. So it's a hair more work, but it would be pretty trivial to have a method that created the needed items on the fly and bound them together.
This is called "Scaffolding".
It really depends on what you are using for your data layer or ORM. Entityspaces, for example, comes with a scaffolding generator.
Absolutely! Scaffolding in Ruby is known as Dynamic Data in ASP.NET. Scott Hanselman speaks to Dynamic Data here.
There's a screen cast from Scott Hunter that shows it off here. It's of note that it's pretty new (still in beta).
You can for simple sites/purposes but it quickly breaks down when you want to do something more complex. Like what happens if you don't want certain fields to be visible, what happens if you have a relationship to a subset of a certain class etc.
Having been down this path before I'm guessing you came at the issue by realizing that:
You spend alot of time creating similar forms/lists etc for similar entities.
You want to minimize this time and are considering if your forms can be automatically generated.
Basically, if you want it to be done automatically then you'll end up creating an overcomplicated system that does half of what you want and actually takes longer to implement.
If however, you want to drastically cut the amount of time doing and maintaining writing repetitive gui code then then I suggest using a declarative style form builder and table builder (like the form builder in ROR).
This lets you quickly create forms/tables without repeating yourself any more than necessary and also gives you the flexibility that you need for complex scenarios.