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I have had to move queries off the main database in order to meet requirements for complex authorization - for example a user with a given authorization role can only view data for individuals in the same institution.
I am using the Breeze .net DocCode sample for guidance, and have copied the premise for the mapping of domain models to DTOs.
get { return ForCurrentUser(Context.Orders).Select(o => new Order {
OrderID = o.OrderID,
....
OrderDetails = o.OrderDetails.Select(od => new OrderDetail
{
ProductID = od.ProductID,
UnitPrice = od.UnitPrice
...
})
The problem is that which mapped properties to .include(entity framework method)/.expand (breeze method) is now a concern of the mapping function (for example, the above code will always return the OrderDetails collection, whether I want them or not). I would like to still only eagerly load/expand properties if the javascript client generated predicate has a .expand directive for that property.
Is this at all possible, or am I stuck with manually defining different mapping functions on the server, depending on what properties I want expanded? (I am happy to use tools such as automapper if that would solve or simplify the problem)
Thank you
You will need to use the ODataQueryOptions as a parameter to your controller method. This gives you the details of the query predicates in your server method, so that you can apply them as needed rather that having them applied automatically. This will let you expand, or not, based upon the query.
See this answer and this answer to see how it works.
This is using BreezeJS and a Breeze controller through to an EF provider. I have a couple of related Entities, lets call them Customer, which has a Navigation Property called Orders which links to a set of Order Entities for that customer.
What I'd like to display on the UI is a summary of Order Counts for a set of customers who match a partial name search. I can do this through returning all the Order objects, but they're quite large objects and I don't really want to return 100's of them when I don't have to. The inlineCount() method seems to always give the count of the top-level entity (Customer) rather than of the sub-Entities, no matter where I place it in the statement.
var predicate = breeze.Predicate.create('displayName', 'contains', partialName);
return this.entityQuery.from('Customers')
.where(predicate)
.orderBy('displayName')
.using(this.manager)
.expand('Orders')
.execute();
The documentation suggests that you can chain the expand in some way, but I have yet to find a syntax which is valid.
Ideally, I'd like to apply a where to the Orders by a property on Order called Status of say 0 (incomplete) and then give me just the count of those matching Orders. ie, return me all the Customer entities, but have a matching order count for each (rather than the whole list of Order objects and filter client-side).
Would appreciate any pointers in the right direction if it's possible to achieve. My current thinking is that I'll have to create a custom method on the server-side controller and do the work there, but before I make assumptions about what OData can support, I thought I'd check here for some confirmation.
So far, this is my best approach (maybe someone can correct me if there's a better way).
On the server, add this method:
public IQueryable<object> CustomerSummaries()
{
return Context.Customers.Select(p => new
{
Customer = p,
ActiveOrderCount = p.Orders.Count(o => o.Status == 1)
});
}
Then on the client end:
var predicate = breeze.Predicate.create('customer.displayName', 'contains', partialName);
return this.entityQuery.from('CustomerSummaries')
.where(predicate)
.using(this.manager)
.execute();
I have a requirement to encapsulate pieces of business logic within a transaction in an OData Web API service. Some of these pieces will need to accept one or more entities.
An example use case might be StockProduct and this might accept a Product entity and a Location entity. It would create the product and update stock records for the Location.
The approach I've taken is to create an unbound OData action that accepts these entities so that both of these can be operated on in a single transaction. Unfortunately neither can Entities be used as an ODataActionParameter nor can they be part of a class and used as a complex parameter.
I can think of a two ways around this:
Create a DTO class that is not an entity that is a mirror of each of my mirror classes and convert from DTO to Model within my action. The problem here is that I already have a DTO for each Model eg. Product.cs and ProductDTO.cs and don't really want to have to create a third class. (Currently, the ProductDTO.cs is used for Posts, Puts, Patches and Deletes and the Product.cs is used for Gets).
Abandon OData actions and create a simple end point that accepts whatever I like. I'm not keen on going down the second route as I'd like to use OData exclusively.
Any thoughts or suggestions?
You can use the ActionConfiguration.EntityParameter() method to bind an entity as a parameter to your OData action method.
Here is an example:
ActionConfiguration validate = ModelBuilder.EntityType<TEntity>()
.Collection.Action("Validate");
validate.Namespace = "Importation";
validate.EntityParameter<TEntity>(typeof(TEntity).Name);
validate.CollectionParameter<string>("UniqueFields");
validate.Returns<ValidationResult>();
However, note that the ModelState will not check against the content of the supplied Entity and will set any missing properties to null and properties exceeding the StringLength(x) annotation in your model will still pass. If you wish to validate the entity itself after, use this bit of code in your action method:
[HttpPost]
public virtual IHttpActionResult Validate(ODataActionParameters parameters)
{
//First we check if the parameters are correct for the entire action method
if (!ModelState.IsValid)
{
return BadRequest(ModelState);
}
else
{
//Then we cast our entity parameter in our entity object and validate
//it through the controller's Validate<TEntity> method
TEntity Entity = (TEntity)parameters[typeof(TEntity).Name];
Validate(Entity, typeof(TEntity).Name);
if (!ModelState.IsValid)
{
return BadRequest(ModelState);
}
IEnumerable<string> uniqueFields = parameters["UniqueFields"] as IEnumerable<string>;
bool result = Importer.Validate(Entity, uniqueFields);
return Ok(result);
}
}
As for your StockProductDTO, it seems to me that this is an new Business Entity by itself and should be treated as such.
You can use a batch request to perform multiple operations within a single request. This allows you to use your existing controllers for inserting your two objects.
https://aspnetwebstack.codeplex.com/wikipage?title=Web+API+Request+Batching
I have a Users table of 76 users and UserGroups table.
Using MVC, OData, a generic repository and EF, I am trying to optimize data retrieval when filtering based on the user group:
/api/Users?$filter=USERGROUPS/any(usergroup: usergroup/ID eq 'Group1')
On the client side, I get the right number of users - 71 (as OData is filtering based on the result), however I want to limit the number of records being returned form the actual query - ie. I do not want to return all records then filter (not optimal for very large data sets).
My API controller method is as follows:
[Queryable(AllowedQueryOptions = AllowedQueryOptions.All)]
public IQueryable<USER> Get()
{
var unitOfWork = new ATMS.Repository.UnitOfWork(_dbContext);
var users = unitOfWork.Repository<USER>()
.Query()
.Include(u => u.USERGROUPS)
.Get()
.OrderBy(order => order.USERNAME);
unitOfWork.Save(); // includes Dispose()
return users.AsQueryable();
}
I read in this post that:
Entity framework takes care of building dynamic query based on the
request.
However, using a SQL Server profiler, the query executed is requesting all the records, rather than a filtered query.
Adding a .Take() to the query does not accomplish the desired result, as we also need the actual number of records returned for paging purposes.
I was thinking of using the grabbing some properties through ODataQueryOptions, but that doesn't seem quite right either.
Is my implementation of Unit of Work and Repository incorrect, in relation to what I am trying to accomplish, and if so, how can this be corrected?
Simple - Just set the Page size for the Queryable atrribute [Queryable(PageSize=10)]
http://www.asp.net/web-api/overview/odata-support-in-aspnet-web-api/supporting-odata-query-options#server-paging
If You'd tell the EF where to apply the options, it would work.
Like this :
//[Queryable(AllowedQueryOptions = AllowedQueryOptions.All)]
public IQueryable<USER> Get(ODataQueryOptions<USER> options)
{
var users = options.ApplyTo(_dbContext.Set<USER>()
.Query()
.Include(u => u.USERGROUPS)
.Get()
.OrderBy(order => order.USERNAME));
return users;
}
Your code didn't work, because it tried to apply the options onto the last line "users.AsQueryable()", so what actually happened, is that EF pull the FULL dataset, and then applied the query onto the last line (that being a in memory collection). And that's why You didn't see that "filter" not being passed to the SQL.
The mechanics are such, that EF tries to apply the Query, to the IQueryable collection that it finds in the code (there's still a question how does it find the correct line).
Ok, so let me explain a little of what I am trying to do.
I have a table called WebsitePage that contains all of the pages on my site with some information about them. Then, I have a Customer table for all of my customers. Then I have another table called CustomerWebsitePage that stores customer values for some of the columns in the WebsitePage table.
So, using the entity framework, I imported these three tables. What I want to be able to do is return a strongly typed WebsitePage list that has any values from CustomerWebsitePage if there are any values for it. So, for example, say one of my customers added a CustomerWebsitePageName for one of my website pages. I want to return a list of WebsitePages that contains the CustomerWebsitePageName instead of the WebsitePage Name in that case. But the original WebsitePage Name for everything else since it wasn't overridden.
The kicker here is that my WebsitePage table has a foreign key to itself for a Parent/Child relationship. So, I also want to return the child WebsitePages at the same time. I tried using a function import to get what I wanted, but then of course I lost the ChildPages.
I have tried just about everything to get what I want using the Entity framework and LINQ. But so far almost everything I try ends up with an exception being thrown. Here are a few:
The EntityCollection has already been initialized
The entity or complex type 'MyEntityModel.WebsitePage' cannot be constructed in a LINQ to Entities query.
I have one idea of how I can get around all this, and that would be to duplicate the ParentPageID into my WebsitePage table, but this really seems to violate a lot of principles and I really just don't want to add the maintenance headache related to this.
Anyone have any ideas how to accomplish this type of thing?
A simple DB diagram. http://images.tehone.com/screenshots/2009-08-17_013009.png
The object that you need to return is a CustomerWebsitePage and not a WebsitePage. The reason is that whatever object you return must know about the customer since the property will need it to determine which field (CustomerPage or WebsitePage) to use.
Considering that, you can have a function CustomerWebsitePage.GetAllPagesForCustomer(Customer c) that would return an enumeration of pages. However, to achieve the functionality you are looking for, you must implement some read-through properties in the CustomerWebsitePage. Let's take the example of Name. Here would be how to implement it in CustomerWebsitePage:
public string Name
{
get{ if( String.IsNullOrEmpty(CustomerWebsitePageName) )
return WebsitePage.Name;
return CustomerWebsitePageName; }
}
For the Children pages, you could have a property:
public IEnumerable<CustomerWebPage> Children
{
get
{
return WebsitePage.Children.Select( it => it.Customer.CustomerID == this.CustomerID ); }
}
Note that with this setup you couldn't run EF Linq queries on these new fields (because they exist only in the objects themselves, not in the database mapping). You can pepper the code with Load() if you want to seamlessly load all the children, but it will cost you in performance. To ensure that all the children are loaded, try the following loading function:
IEnumerable<CusomterWebPage> GetAllPagesForCustomer(Customer c)
{
return Context.CustomerWebPageSet.Include("WebsitePage").Where( it => it.Customer.CustomerID == c.CustomerID );
}