I'm working on a project that groups data by a "customer id". When the user logs in, they're limited to that customer and that customer only.
I'm working with SubSonic3, and what I've got looks something like this:
public IEnumerable<Models.Foo> FindFoo(int userID, string searchText, int pageIndex, int pageSize)
{
return from item in Foo.GetPaged(pageIndex, pageSize)
where (item.Name.Contains(searchText) ||
item.Description.Contains(searchText)) &&
item.CustomerID == CurrentCustomerID()
select new Models.Foo(item);
}
What I'd like to do is abstract away the item.CustomerID line, because that's going to happen for every query, without fail, so it would be simpler (and more secure) to do it in one place and guarantee it'll happen everywhere.
So, my question is: can this be done, and if so, how?
As far as subsonic generated classes are partial you can add some interface to them... Just create you're interface with CustomerID property (for example name it ICusomerEntity) and make partial for any of generated classes that will apply this interface to them... then just use the generic subsonic methods to rerieve ICustomerEntity, not the specific class..
For example you can make generic method called GetCustomerEntity with constraint T:ICustomerEntity which will return IQueriable with a bascic query comparing CustomerId with the one of logged user..
Hope it helps...
Related
I've been searching for an answer on how to delete ALL records from a table using LINQ method syntax but all answers do it based on an attribute.
I want to delete every single record from the databse.
The table looks like so:
public class Inventory
{
public int InventoryId { get; set; }
public string InventoryName { get; set; }
}
I'm not looking to delete records based on a specific name or id.
I want to delete ALL recods.
LINQ method syntax isn't a must, bt I do prefer it since it's easier to read.
To delete all data from DB table I recommend to use SQL:
Trancate Table <tableName>
Linq is not meant to change the source. There are no LINQ methods to delete or update any element from your input.
The only method to change you input, is to select the (identifiers of the )data that you want to delete in some collection, and then delete the items one by one in a foreach. It might be that your interface with the source collection already has a DeleteRange, in that case you don't have to do the foreach.
Alas you didn't mention what your table was: Is it a System.Data.DataTable? Or maybe an Entity Framework DbSet<...>? Any other commonly used class that represents a Table?
If you table class is a System.Data.DataTable, or implements ICollection, it should have a method Clear.
If your tabls is an entity framework DbSet<...>, then it depends on your Provider (the database management system that you use) whether you can use `Clear'. Usually you need to do the following:
using (var dbContext = new MyDbContext(...))
{
List<...> itemsToDelete = dbContext.MyTable.Where(...).ToList();
dbContext.MyTable.RemoveRange(itemsToDelete);
dbContext.SaveChanges();
}
From what I've read, I'm supposed to be using ViewModels to populate my views in MVC, rather than the model directly. This should allow me to pass not just the contents of the model, but also other information such as login state, etc. to the view instead of using ViewBag or ViewData. I've followed the tutorials and I've had both a model and a viewmodel successfully sent to the view. The original problem I had was that I needed a paginated view, which is simple to do when passing a model alone, but becomes difficult when passing a viewmodel.
With a model of
public class Instructor {
public string forename { get; set; }
public string surname { get; set; }
}
and a viewmodel of
public class InstructorVM {
public Instructor Instructors { get; set; }
public string LoggedIn { get; set; }
}
I can create a paginated list of the instructors using the pure model Instructor but I can't pass InstructorVM to the view and paginate it as there are other properties that aren't required in the pagination LoggedIn cause issues. If I pass InstructorVM.Instructors to the view, I get the pagination, but don't get the LoggedIn and as this is just the model, I may has well have passed that through directly.
An alternative that was suggested was to convert/expand the viewmodel into a list or somesuch which would produce an object like this that gets passed to the view
instructor.forename = "dave", instructor.surname = "smith", LoggedIn="Hello brian"
instructor.forename = "alan", instructor.surname = "jones", LoggedIn="Hello brian"
instructor.forename = "paul", instructor.surname = "barns", LoggedIn="Hello brian"
where the LoggedIn value is repeated in every row and then retrieved in the row using Model[0].LoggedIn
Obviously, this problem is caused because you can only pass one object back from a method, either Instructor, InstructorVM, List<InstructorVM>, etc.
I'm trying to find out the best option to give me pagination (on part of the returned object) from a viewmodel while not replicating everything else in the viewmodel.
One suggestion was to use a JavaScript framework like React/Angular to break up the page into a more MVVM way of doing things, the problem with that being that despite looking for suggestions and reading 1001 "Best JS framework" lists via Google, they all assume I have already learned all of the frameworks and can thus pick the most suitable one from the options available.
When all I want to do is show a string and a paginated list from a viewmodel on a view. At this point I don't care how, I don't care if I have to learn a JS framework or if I can do it just using MVC core, but can someone tell me how to do this thing I could do quite simply in ASP.NET? If it's "use a JS framework" which one?
Thanks
I'm not exactly sure what the difficulty is here, as pagination and using a view model aren't factors that play on one another. Pagination is all about selecting a subset of items from a data store, which happens entirely in your initial query. For example, whereas you might originally have done something like:
var widgets = db.Widgets.ToList();
Instead you would do something like:
var widgets = db.Widgets.Skip((pageNumber - 1) * itemsPerPage).Take(itemsPerPage).ToList();
Using a view model is just a layer on top of this, where you then just map the queried data, no matter what it is onto instances of your view model:
var widgetViewModels = widgets.Select(w => new WidgetViewModel
{
...
});
If you're using a library like PagedList or similar, this behavior may not be immediately obvious, since the default implementation depends on having access to the queryset (in order to do the skip/take logic for you). However, PagedList, for example has StaticPagedList which allows you to create an IPagedList instance with an existing dataset:
var pagedWidgets = new StaticPagedList<WidgetViewModel>(widgetViewModels, pageNumber, itemsPerPage, totalItems);
There, the only part you'd be missing is totalItems, which is going to require an additional count query on the unfiltered queryset.
If you're using a different library, there should be some sort of similar functionality available. You'll just need to confer with the documentation.
I have a model with some parameters that a User should be able to see but not edit and others they should be able to edit. The same is true of the Author. So, I used [UIHint("Author")] and [UIHint("User")] attributes and wrote a couple editor templates, like so:
#inherits System.Web.Mvc.WebViewPage
#if (ViewBag.RoleId > (int)Role.RoleEnum.Author)
{
#Html.TextBoxFor(m => m, new { disabled = "disabled" })
}
else
{
#Html.TextBoxFor(m => m)
}
This almost does what I want. I'd like to be able to apply these attributes to booleans and get check boxes - like the default EditorFor. I suppose I could make another template and use something like [UIHint("AuthorBool")], but I'm hoping to come up with something better.
Hi Oniel,
You could create separate ViewModels for each type of user and use the data annotation of [ReadOnly]. But then you get into the realms of large amounts of repetition.
Personally I would recommend that you create your own version of each data type and implement standard role based handling using additionalmetadata data annotations to customise. Okay bit of work to begin with but then massively re-usable and highly portable.
Example:
[UIHint("MyCustomTemplateControl")]
[AdditionalMetadata("DenyEditUnlessInRole", "Admin")]
public string MyName { get; set; }
or:
[UIHint("MyCustomTemplateControl")]
[AdditionalMetadata("DenyEditIfInRole", "StandardUser")]
public string MyName { get; set; }
You can perform a code based / database based lookup in a class somewhere else that your datatypes templates query to make a decision on whether a user/role should get read/edit access to this property.
Does this make sense?
As a third option, create an editortemplate for the entire object and only include those fields and field types you are interesting in exposing.
MVC is so flexible - I suppose in the end it depends on how DRY do you want to make your code.
Good luck!
Dan.
I'd like to include some additional functions in my Doctrine 2 entities to contain code that I'm going to have to run quite frequently. For example:
User - has many Posts
Post - has a single user
I already have a function $user->getPosts(), but this returns all of my posts. I'm looking to write a $user->getActivePosts(), which would be like:
$user->getPosts()->where('active = true') //if this were possible
or:
$em->getRepository('Posts')->findBy(array('user'=>$user,'active'=>true)) //if this were more convenient
As far as I can tell, there's no way to get back to the entity manager though the Entity itself, so my only option would be
class User {
function getActivePosts() {
$all_posts = $this->getPosts();
$active_posts = new ArrayCollection();
foreach ($all_posts as $post) {
if ($post->getActive()) {
$active_posts->add($post);
}
}
return $active_posts;
}
However, this requires me to load ALL posts into my entity manager, when I really only want a small subset of them, and it requires me to do filtering in PHP, when it would be much more appropriate to do so in the SQL layer. Is there any way to accomplish what I'm looking to do inside the Entity, or do I have to create code outside of it?
I think you should implement the method on the PostRepository rather than on the entity model.
I try to keep all model related logic in the repositories behind "domain specific" methods. That way if you change the way you represent whether a post is active or not, you only have to change the implementation of a single method instead of having to find all the active = true statements scattered around in your application or making changes in an "unrelated" entity model.
Something like this
PostRepository extends EntityRepository {
public function findActiveByUser($user){
// whatever it takes to get the active posts
}
}
I have a database that has a user search screen that is "dynamic" in that I can add additional search criteria on the fly based on what columns are available in the particular view the search is based on and it will allow the user to use them immediately. Previously I had been using nettiers for this database, but now I am programming a new application against it using RIA and EntFramework 4 and LINQ.
I currently have 2 tables that are used for this, one that fills the combobox with the available search string patterns:
LastName
LastName, FirstName
Phone
etc....
then I have an other table that splits those criteria out and is used in my nettiers algorithms. It works well, but I want to use LINQ..and it doesnt fit this model very well. Besides I think I can pare it down to just one table with linq...
using a format similar to this or something very close...
ID Criteria WhereClause
1 LastName 'Lastname Like '%{0}%'
now I know this wont fit specifically into a linq query..but I am trying to use a univeral syntax for clarity here...
the real where clause would look something like this: a=>a.LastName.Contains("{0}")
My first question is: Is that even possible to do? Feed a lambda in to a string and use it in a Linq Query?
My second question is: at one point when I was researching this before I found a linq syntax that had a prefix like it.LastName{0}
and I appear to have tried using it because vestiges of it are still in my test databases...but I dont know recall where I read about it.
Is anyone doing this? I have done some searches and found similar occurances but they mostly have static fields that are optional, not exactly the way I am doing it...
As for your first question, you can do this using Dynamic Linq as described by Scott Gu here
var query = Northwind.Products.Where("Lastname LIKE "test%");
I'm not sure how detailed your dynamic query needs to be, but when I need to do dynamic queries, I create a class to represent filter values. Then I pass that class to a search method on my repository. If the value for a field is null then the query ignores it. If it has a value it adds the appropriate filter.
public class CustomerSearchCriteria{
public string LastName { get; set; }
public string FirstName { get; set; }
public string PhoneName { get; set; }
}
public IEnumberable<Customer> Search(CustomerSearchCriteria criteria){
var q = db.Customers();
if(criteria.FirstName != null){
q = q.Where(c=>c.FirstName.Contains(criteria.FirstName));
}
if(criteria.LastName!= null){
q = q.Where(c=>c.LastName.Contains(criteria.LastName));
}
if(criteria.Phone!= null){
q = q.Where(c=>c.Phone.Contains(criteria.Phone));
}
return q.AsEnumerable();
}