I’m using EF 4.0. I’ve got fluent API mapping between my model and database. In one of small utility applications I want just to display my entities as a table, so I can add/edit/delete records from the WPF user interface using DevExpress Grid control. I followed their video http://tv.devexpress.com/#DXGridWPFBindEF4 and now I see my data in the grid, but I can’t edit it.
control.gridUsers.ItemsSource = new LinqServerModeSource
{
ElementType = typeof (User),
KeyExpression = "Login",
QueryableSource = control._dbContext.Users
};
Is there any way of making this binding working in both ways?
Thanks
Not with the LinqServerModeSource as datasource because it is read-only. The "server mode"-datasources are intended to display large datasources. They implement a paging mechanism so not all of the data from the server is queried and transfered to the client but only the currently visible part.
I actually got response from DevExpress support team which helped me.
http://www.devexpress.com/Support/Center/p/Q442601.aspx
Related
I am building an application that will interface with my database backend using EF 6. I have my database built so I will be going the database first approach.
One of the goals will be to utilize the grid control from DevExpress and allow the user to view a Master/Detail style of information for each Facility in my Facility table.
I need the ability to update/insert so I would assume using a view would not be as good as actually supplying the context to the grid's data source.
My question is trying to understand the overhead involved with Entity Framework. If my table contains 20 columns but my Grid only needs 10 of these for viewing/updating/inserting does the application still load ALL of the information into memory? Am I better off using a view for the grid and some form of custom routines for an update?
It doesn't necessarily load all of the columns. If you're smart about it, you can only have it load those columns that you need using LINQ to Entities.
For example:
var records = db.MyTable.Where(...Some condition...).ToList(); will return all the columns.
But doing it this way
`var records = db.MyTable.Where(...Some condition...).Select(x => new MyModel { ...some fields here... }
will only load those fields that are specified.
I've worked with DevExpress and Entity Framework combined before, and I can tell you that it's relatively painless as long as you understand what you're doing with Entity Framework, and don't just blindly have your grids make queries that can get expensive.
I'm using breezejs with an entity framework 5 model. The model is the old-school edmx/objectcontext style- not the newer dbcontext/poco style.
The model is shared with some wcf ria services domain services so I cannot switch to entity framework 6 or poco style entity framework at this time.
When using wcf ria services, if you wanted to add a property to an entity beyond what is generated by entity framework you could create a partial class, define the property and annotate it with the datamember attribute. Wcf ria services treats this new property like any other property and sends it to the client from the server and back to the server.
Is there a way to do the same thing with breezejs? Without moving entirely away from the automatic metadata generation goodness that comes with using entity framework?
Using fiddler I can see the property I want exposed is transmitted to the client during a query request.
I've looked at the documentation here http://www.breezejs.com/documentation/extending-entities but none of the examples seem to fit this scenario.
Breeze supports unmapped properties, these are properties that are declared on your javascript constructor that cannot be matched to any property in metadata. By default these properties are both persisted locally and sent to the server on a save. This is described in the link you mentioned:
http://www.breezejs.com/documentation/extending-entities
var Customer = function () {
this.myUnmappedProperty = "anything22";
};
myEntityManager.metadataStore.registerEntityTypeCtor("Customer", Customer);
These values will be available on the server after a SaveChanges call via the 'UnmappedValuesMap' property on each EntityInfo instance.
var unmappedValue = entityInfo.UnmappedValuesMap["myUnmappedProperty"];
What is sounds like you are looking for is "unmapped" properties to go in the "other" direction, i.e. from the server to the client. What might work for that but we haven't tried is adding a property to your server side EF class ( via the partial class mechanism) and mark it up for Json serialization. It "should" then get serialized down to the client, even though it won't show up in Metadata.
If this does NOT work, please post back here and we will consider it as a breeze feature request. The basic idea does make a lot of sense and we should support it.
I need some help in understanding the benefit of using Breeze JS in a Visual Studio MVC project.
With MVC, using razor, I can bind my model properties to controls on the page and have any changes user makes sent back to the server without me writing any code. So, I am not really understanding if in this situation use of Breeze can be beneficial.
Certainly, I am not looking at the whole picture. And that is the reason I am asking this question here. Can anyone explain.
TIA.
kr
breeze is very helpful when you use ORM like NH\EF (also good for nosql and mongo)
if you do stuff like TPT\TPH and circular ref data it's hard to serialize by yourself
breeze takes care of that part for you
you can get your entities on the client side and keep change tracking
also no need to write sql\sp\functions to query data you can do all that on the client side
breeze supports client side cache with ease
breeze also works great with angularjs and knockout, if you bind data to the scope and then use breeze manager to delete or add more data no need to push or splice it breeze does that for you
breeze can do so much more so please check out the docs and features and find out what breeze can do for your project
I am using MVC Pattern and breeze will help us to integrate our typeScript interface generated from T4Ts taking the advantage of have strongly typed entities.
export interface Library extends breeze.Entity {
Category: string;
Name: string;
}
var manager = new breeze.EntityManager('api/library');
var query = new breeze.EntityQuery()
.from("Library");
manager.executeQuery(query).then(data => {
var employees = <Library []>data.results;
}).fail(e => {
alert(e);
});
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.
I have a few tables that reference the same table. For example:
Person has an address.
Business has an address.
When using the models I would like to do this in the controller:
person.Address.Zip
business.Address.Zip
I'm coming from a rails background where I can just declare a relationship and have all the above functionality. Force loading of the address when I get the object (person or business).
I'm new to entity framework, and I'm struggling with how to achieve that functionality. I can't include the table in both models (person and business). If I use repository pattern and add the objects to a partial for the class, then I'm using lazy loading.
Am I looking at this wrong? Any suggestions for patterns I could use?
If your using Entity Framework 4.0 with Visual Studio 2010 lazy loading is automatic.
If your using Entity Framework 1.0 your life just got harder...
To eager load with EF1 you have to use the Include() method on your ObjectQuery and specify which navigation properties ( address ). For example:
ModelContainer.Persons.Where(#p => #p.Id == 39 ).Include("Address")
For "lazy" loading you have to manually load all of the FK associations manually. For example:
var myPeople = ModelContainer.Persons.Where(#p => #p.Id == 39
if( !myPeople.Address.IsLoaded() )
myPeople.Address.Load()
Another option is to modify how EF1 generates your model types and include lazy loading out of gates.
http://code.msdn.microsoft.com/EFLazyLoading
Previously, I was creating an ADO.NET Entity Data Model for each controller.
Now I've created one Data Model for all tables (it's not a monstrous db). That way I can include the tables when I query for eager loading.
If anyone has a better suggestion. Let me know. If anyone knows the correct behavior with a large database, please comment. Would you want one large edmx file to represent the database?
Ideally you should be able to traverse the object model to get most of the data you need, starting with a reference to the current user object.