I want to create a custom collection and add my own custom Add method.
Scenario:
Teacher.Students.Add(Student s)
I want to put LINQ methods to save the teacher/student relationship to the database, not just add it to the list.
How can I do that? How can I know what "Teacher" object this is?
Your best bet is to set up and configure an ORM (Object-relational mapping), such as NHibernate, that will manage this for you. In effect, you set up the data model, and the ORM framework will take care of persisting that information for you.
Related
I'm aplying DDD in Laravel.
In this architecture, the entity (conformed by the corresponding value objects) is not a Laravel Model extended class (because the domain layer needs to be agnostic to the infrastructure)
So... when I retrieve some data inside the repository implementation, the result is a stdclass object, and I need to return it as the entity object.
Anybody knows the best approach to do this?
Thanks!
To get this, I tried to convert from stdclass to entity by manual, but it's look hacky and dirty.
Ok, got it.
I found two different approaches, just in case others are fighting with the same problem.
Option 1: Embracing the Eloquent Active Record.
Inside the infrastructure layer, I created a Eloquent model to represent the Entity, and I use it as a vehicule for eloquent queries. Like this, all the conection with the framework stay contained in the infrastructure, without polluting other layers.
Option 2: Apply Doctrine in Laravel.
Doctrine has a package for laravel. Doctrine, as occurs in Synfony, is using data mapping, so no worries with that.
Thanks anyway!
I want to store changes to all fields in Eloquent model into database.
I can do it using created and updated events but there is a problem with multiple foreign relations (described as separate tables).
Example:
User
login
Roles -> hasMany
When I update login field it is easy to write old and new value into database, but when I update Roles relation nothing happens.
How can I track all foreign relations (like hasMany, hasManyThrough, ManyToMany)?
Owen-it has a very nice Library called laravel-auditing, which keeps an easy to query list of all changes that are made to a model, and I think it does quite an awesome piece of work. Have used it and it is worth it to try out.
There is no embedded and simple method to do it.
Eloquent doesn't provide any method to implement observers on related models by design. Many proposal in this way have been rejected by Taylor (just one example).
The only thing you can do, is to create your own methods to do it.
You have many possibilities, here are some of them in order of complexity (some of them are "dirty" :-)
add a created and updated observer on each related model
override the save() or create your own saveAndFire() method on your eloquent instances, and from that method retrieve the parent and call its log methods before saving. (this is a little bit "dirty" imho)
encapsulate all your persistence layer and fire events yourself on saving objects (look at the repository pattern, for example)
My intent is to create a generic (not in C# meaning) database model for Windows Phone using linq to sql. User of such model should be able to pass an array of his data object types (classes marked with Table attribute) to model's contstructor, and then model should take care about adding related tables to database and provide API for CRUD operations.
But then I've found out that in order to add tables to database, your data context (class inherited from DataContext class) have to declare each table as a property! That's embarrassing. Does this fact mean that my idea is not implementable? Because I obviously cannot add properties to my DataContext-based in the runtime.
So my question is, am I right in my judgments? If yes, are there some workarounds to solve this issue?
Thanks in advance.
EDIT: better question tagging, for somebody finally notice this.
You do not need to use a strongly typed DataContext (a class inheriting from DataContext and declaring properties for each table). You can do something like the following instead
var context = new DataContext("connection string", new AttributeMappingSource());
var table = context.GetTable<T>();
where T is some type marked with the Table attribute.
I'm new to MVC & EF. I'm developing the MVC project with model first approach. In my project i have different entities like-customer,employee,product,etc. and i created association between them like 1 to many in customer-employee like this. and after creating this association; it is generating navigation property in customer entity i.e, Employees (collection object) for employee entity.
I want to modify this collection class and i want to add some more methods on it. Is it possible? How to do this if possible?
thanks.
The property is generated with ICollection<Employee> type. You can in theory create your own class implementing this interface and initialize the property for example in Employee constructor but the property will still expose the interface. Changing return type of the property requires change in class generator (you should use T4 template which would make this easy task). By changing property's return type to your collection you can lose some EF functionality.
I have a populated object from using the entity framework. Let's call it Order. The order has different properties such as Id, OrderDate, BillingAddress and so on. I need to let users update this data.
What's the best way to display this data in a form, while enforcing data annotations such as [Required]? I see MetadataType mentioned a lot, but I haven't seen how I can connect the dots with displaying the data as well.
One approach that I could take, but I'd like to avoid because of redundancy, is creating my own model object that has nearly identical properties. Then I would just need to basically just copy entity framework object A to new object B, where B has all my lovely data annotations. It just seems like there might be a better way.
Could anyone provide me with an example of a good way to accomplish this?
The "better way" is a big reason EF Code First is great. Otherwise, the only other way to do what you need is to do a mapping.