I have 5 tables to use in one mvc view. So I created a database view and want to map this view into EF for using it as a model. How can I do?
I have successfully used the following in a code-first application where I used Sql Server Functions as 'views' to run complex queries against the database to fetch data (I did not need inserts or updates).
List<MyClass> myClassItems =
dbContext.Database.SqlQuery<MyClass>("Select * from dbo.MyClassFunction(#param)", param).ToList();
I returned myClassItems as the result of a Repository function, with MyClass a class with properties that match the columns that the MyClassFunction returned.
Related
Is there a native Entity Framework way to create a database (LocalDB) without populating it with the tables defined in my DbContext class (code first)? (I want to use my own database creation script, with default values, etc, and I want to be able to clear it out beforehand using context.Database.Delete().)
If I use context.Database.Create() then EF will populate the database with tables. If not then no database exists and I cannot connect to it to run my database creation SQL.
I am providing a connection string like this:
data source=(LocalDB)\\MSSQLLocalDB;integrated security=True;attachdbfilename=|DataDirectory|\\FileName.mdf;connect timeout=30;MultipleActiveResultSets=True;App=EntityFramework
Create a base DbContext instance that uses the same database, and use it to do the recreation.
var my_context = new MyDbContext(connection_string);
var creater_context = new DbContext(connection_string);
creater_context.Database.Delete();
creater_context.Database.Create();
// now use my_context on the database.
We have a table (AttendanceType) in our database which have many fields with multiple options. this multiple options are defined in single table. So, instead of creating separate Option table for each option we have single table (Option_Data) with key to identify each option type (Record).
Example : AttendanceType table has following fields
ID
Description
Category (Payroll / Accrual)
Type (Hours / Days)
Mode (Work hours / Overtime / ExtraHours)
Operation (Add / Minus)
These fields have options (data as shown above in brackets) which comes from Option_data table. We have created separate views from this Option_data table example: vwOption_Attendance_Mode, vwOption_Attendance_Operation etc.
Now, how we can link this view in breeze so the reference data come automatically.
We are using EF6, SqlServer, Asp.Net WebApi. When the table relationship is defined in SQL Server Breeze works perfectly and manages the relational data. In this case we cannot define relationship in SQL Server between Table and Views.
How we can code it so Breeze can manage the relational / reference data for us? If you require further clarification please let me know.
Edit # Jay Traband : Let say a single table (ie: AttendanceType) has fields which get reference/lookup data for its field from Views. How in breeze we can relate them (table with views), as in SQL Server we cannot.
My reference points is when Tables are related breeze does excellent job. I want to achieve same with table and views.
Breeze gets its metadata (including the relationships between entities) from EF. You'll need to tell EF about the relationship between the tables and views, even if there is no such relationship defined in SQL Server. This SO post provides some clues, and this blog post gives some related information about creating relationships in the designer.
I would like to use Entity Framework 5 from which I can use one MVC Model that can span two or more databases.
Is this possible?
In other words, have one EF model that can use two or more databases. Because with MVC, you can only use 1 model in a View. Some of the data with some of the Views can come from different databases. In order to use the model binder in MVC and map it to EF 5 columns, I would need to accomplish this.
ASP.NET MVC is NOT dependent on Entity Framework.
ASP.NET MVC is a framework for building web application that stick with the Model View Controller pattern. It is not bounded to Entity framework. It can work with any data access technologies like LINQ2SQL / Entity Framework / Pure ADO.NET etc.. that means you can develop MVC application with or without using Entity Framework.
I assume you want to get data from 2 different databases and load a model object. You can do that by writing a select query which gets data from 2 databases and put that in a Stored procedure and put that proc in your database which your DbContext is communicating with. Then execute the stored proc and load the Model object.
a sample procedure which gets data from 2 databases
CREATE PROCEDURE GetCustomer(#id int)
AS
BEGIN
SELECT C.ID,A.DateReceived
FROM FirstServerName.DbName.dbo.Customer C
INNER JOIN SecondServerName.DbName.dbo.Applications A
ON A.CustomerID=C.CustomerID
AND A.CustomerID=#id
END
To execute the stored proc with Entity framework, you can use Database.SqlQuery method
var idParam = new SqlParameter { ParameterName = "#Id", Value = 414};
var result = context.Database.SqlQuery<Customer>
("exec GetCustomer #Id", idParam).ToList();
This will execute your proc and load the data to an instance of Customer class, assuming the result set structure and your model class structure look similar.
You may need to adjust the permissions of the stored proc to read data from the relevant databases /tables.
What Shyju is saying is that MVC doesn't care or know anything about your Entity Framework data model or database. As such, the idea that an MVC model can span two databases is like saying an airplane can span two hammers.
As above the M in MVC is whatever you want it to be. Microsoft don't specify what Model actually is. It certainly doesn't have to be an EF Model (although some code samples from MS use that as an example)
I'd suggest that M should be a ViewModel and should be unrelated to your data layer. Then use a tool like Automapper to map from a domain model to a ViewModel. The ViewModel encapsulates the data you want to show and any specific web view specific information that you want to display. Then when you post back the ViewModel you can use that to update the domain models appropriate fields etc and persist that to both databases. This is a good article on the subject of ViewModels http://lostechies.com/jimmybogard/2009/06/30/how-we-do-mvc-view-models/
I am developing MVC application and using razor syntax. I have used model first method.
I have two entities, Customer and Lead. Lead is inherited from Customer.
When IsActive property is true then Customer treated as a Lead, otherwise it will be a customer.
Please check edmx file image.
Now, In regular entities we just deal with single entity and single table.
In this case how can I handle , Save and Load process. beacuse I have to store and load the record from 2 tables of DB.
Is Regular Index View will work here ?
When using inheritance in the Entity Framework you will have a single DbSet on your DbContext that exposes your hierarchy. In your database you have several options for configuring your table structure. For example you can use:
Table per Hierarchy
Table per Type
Table per Concrete type
(See this blog for a nice explanation: Inheritance in the Entity Framework.
In your queries however, you don't have to think about this. Your queries will have the following structure:
var leads = from l in dbcontext.Leads.OfType<Customer>()
select l;
The OfType() filters your collection to a subtype in your hierarchy. If you skip the OfType you will get both customers and leads in your resulting query.
I have an entity (Org) in my Entity Framework that has a foreign key with a table that is in another database (BusinessUnit). We need the foreign key to get the description of the BusinessUnit linked with the Org. In the past (old project without Entity Framework) we were using a stored procedure to return all the information about this entity, including the BusinessUnit description, using a join. So now my problem is how to display the same information than before using Entity Framework.
I've tried, once I load my Org entity from database, to make a loop accessing to BusinessUnit to get the description for each Org, but this is too slow. My other idea was use a store procedure, but I need an extra field on my entity and Entity Frameworks gives me an 3004 error: No mapping specified for my property. I was thinking to use a complex type, but I'm not sure if it's what I need keeping in mind I have to add just a field to my entity. In that case, could I use the complex type just for "select" operations and keep my original entity for the rest of CRUD operations?
How should I proceed?
Thanks.
EF is not able to execute queries across multiple databases. If you need to perform such query you must either use database view and map the view as a new entity (it will be readonly - making it updatable requires mapping insert, update and delete stored procedures) or divide your data querying into two separate parts to load data from both databases. Divided querying can either use two contexts or you can get data from the second database using stored procedure.
The reason why you got the error is that you added the property in EDMX. EDMX can contain only properties mapped to your first database. EDMX generates entity code as partial classes If you need property manually populated from the second database you have to create your partial part (partial class) for entity and add the property in code.