Is there a way to convert data in an existing database into objects that can easily be put into a seed method?
Essentially I'd like to let some people add lines to my DB via a form and then convert that into an object that I can re-seed the DB anytime I need to make changes.
The database itself is created via code-first using the following model:
public class Combo
{
public int Id { get; set; }
public string MainPrefix { get; set; }
public string MainDescriptor { get; set; }
public string MainDish { get; set; }
public string Connector { get; set; }
public string SecondaryDescriptor { get; set; }
public string SecondaryDish { get; set; }
}
High level untested idea:
Create a new T4 template which will use either your context or direct SQL to query database and generate either C# static class with method (which will return collection of object created from database data) or SQL insert commands. Depending on what you choose you will either call static method in Seed to get all entities you want to insert or simply load the created SQL script and execute it.
You can also do the same without T4 by using Code Dom (if you want to generate C# code) and creating a new custom tool for visual studio.
These features can be part of your project or the result (C# code) can be compiled in separate external assembly.
Related
Assume I've read and googled, and I still don't know what I'm doing incorrectly. Whenever I try to execute
_dbContext.Set<T>().Add(aMediaObjectWithAssociatedProvider);
_dbContext.SaveChanges();
I get the dreaded efcore violation of primary key constraint reference table
I have a class as such:
public class Media : BaseModel
{
public virtual string Title { get; set; }
public virtual string? Description { get; set; }
public virtual string Source { get; set; }
public virtual Guid? MediaTypeId { get; set; }
public virtual Guid? ProviderId { get; set; }
public virtual DateTime? StartDate { get; set; }
public virtual DateTime? EndDate { get; set; }
public virtual Provider? Provider { get; set; }
}
The BaseModel class is
public abstract class BaseModel : IBaseModel
{
public virtual Guid Id { get; set; }
}
The Provider class is as such:
public class Provider : BaseModel
{
public virtual string Name { get; set; }
public virtual string? ApiUsername { get; set; }
public virtual string? ConfigurationSection{ get; set; }
}
My DBContext has the following:
protected override void OnModelCreating(ModelBuilder mb)
{
mb.Entity<Media>().HasKey(x => x.Id);
mb.Entity<Media>().HasOne(p => p.Provider).WithOne().HasForeignKey<Media>(x => x.ProviderId);
}
The code for inserting a new object is as follows:
public T Insert(T oneObject)
{
try
{
// Ensure the entity has an ID
if (oneObject.Id == Guid.Empty)
{
oneObject.Id = Guid.NewGuid();
}
_dbContext.Set<T>().Add(oneObject);
_dbContext.SaveChanges();
}
catch (Exception error)
{
_logger.LogError(error.Message, error);
}
return oneObject;
}
Assume that providers are static, in a sense that they already exist in their table, and I don't want to add new providers when I save media... Media just needs to have a provider.
I know exactly what is happening (the model, after travelling through json back through the api to the server is losing context, but I'm also trying to build a repository type of system where I don't have to build complex save logic for every object. (hence why i'm hand wringing over adding code that loads existing providers).
This problem specifically began rearing its head when I was saving new Media objects into the database with existing Providers. I am still mulling over how to look up children dynamically, but i'm not quite there yet.
I've been at this for so long, i'm about ready to give up on efcore relations and just rebuild the models as single objects, and handle all of the manipulation in javascript. And I don't like this idea.
I know for a fact that there will be questions for more code, but please let me know what. Again, I'm just stepping into .net core / ef core so this code-first is a little confusing for me. Thanks
You may have 2 options to try. Do backup your whole project and database beforehand. Clone your database to another database name. Try these either one option using new cloned database for testing.
No.1
Set "newid()" without quotes in your ID's default value in sql server. So you don't need to use Guid.NewGuid() in code every insert. newid() will auto generate GUID.
No. 2
How about removing primary key from ID (GUID) and then creating new column "UID" (running number) and set UID (running number) as primary key and enable its identity? You need to change all other tables too. And re-link UID each other if you use relationship. This way, your UID will not have existing number when insert.
I am developing a contact log in a website using VS 2010, MVC3 and EF 5 - the entities are created using code first. The data is stored in an SQL Server 2008 R2 set of databases. I want to display a summary of the contact log and have created a view.
CREATE VIEW dbo.ContactLogSummaries
AS
SELECT
CLE.ContactLogEntryID,
CLE.CaseID,
'Test' AS ContactName,
EU.UserName As OfficeUser,
CLE.DateAndTimeOfContact,
CLC.Category,
CLE.ContactDetails
FROM
ContactLogEntries AS CLE
JOIN
ContactLogCategories AS CLC
ON CLE.ContactLogCategoryID = CLC.ContactLogCategoryID
JOIN
Control.dbo.EndUsers AS EU
ON CLE.UserID = EU.EnduserID
There are two entities in the Contact Log database (ContactLogEntries and ContactLogCategories) and a database first entity Control.dbo.EndUsers in another database. The contact log could contain a large number of records. I want to be able to display just the records for a specific case.
My question is in two parts:
Can I use the SQL view directly to display a summary on a web page (perhaps by reading it into a class)
Can I create a code first object equivalent to the SQL view.
You can just map the Entity directly to the view using TableAttribute (data annoations), or ToTable in your Fluent Mappings...
For example using data annotions:
using System;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
public namespace whatever.mynamespace
[Table("dbo.ContactLogSummaries")] //<-- this is your view
public class ContactLogSummary
{
...
}
}
Found a simple solution to question 1:
public class ContactLogSummary
{
public int ContactLogEntryID { get; set; }
public int MaternalCaseID { get; set; }
public String ContactName { get; set; }
public String OfficeUser { get; set; }
public DateTime DateAndTimeOfContact { get; set; }
public String Category { get; set; }
public String ContactDetails { get; set; }
public static List<ContactLogSummary> LoadContactListSummary
(int caseID, String connectionString);
{
MyDataContext dbContext = new MyDataContext(connectionString);
return dbContext.Database.SqlQuery<ContactLogSummary>
("SELECT * FROM dbo.ContactLogSummaries WHERE MaternalCaseID = #CaseID ORDER BY ContactLogEntryID DESC",
new SqlParameter("CaseID", caseID)).ToList();
}
It does all that's required so, although I'm interest in an answer to question 2 I have a working solution.
I'm trying to use the entity framework to communicate with my existing DB. This is thus DB first. Using sql server and c#. The problem is that I would like to use a sequential GUID, generated by the database.
Each time I run the code, my controller pastes the GUID assigned to lutRoughagePhysicalSiloId to the DB (most of the time lutRoughagePhysicalSiloId is just an empty GUID (000..) since I don't fill it). As far as I can see, this should not be happening since I use [DatabaseGenerated(DatabaseGeneratedOption.Identity)].
Any Ideas?
SQL code
CREATE TABLE [dbo].[lutRoughagePhysicalSiloType]
(
[RoughagePhysicalSiloTypeId] UNIQUEIDENTIFIER NOT NULL PRIMARY KEY UNIQUE DEFAULT NEWSEQUENTIALID(),
[PhysicalSiloTypeName] NVARCHAR(50) NOT NULL UNIQUE
)
(Notice the Default value newsequentialId() that gets generated as default by sql server)
Automatic created modelview (DB first):
namespace guiIlvoDairyCowBarn.Models
{
using System;
using System.Collections.Generic;
public partial class lutConcentratePhysicalSiloType
{
public lutConcentratePhysicalSiloType()
{
this.lutConcentratePhysicalSiloes = new HashSet<lutConcentratePhysicalSilo>();
}
public System.Guid ConcentratePhysicalSiloTypeId { get; set; }
public string PhysicalSiloTypeName { get; set; }
public virtual ICollection<lutConcentratePhysicalSilo> lutConcentratePhysicalSiloes { get; set; }
}
}
Buddy class
namespace guiIlvoDairyCowBarn.Models
{
[MetadataType(typeof(lutRoughagePhysicalSiloMD))]
public partial class lutRoughagePhysicalSiloType
{
public class lutRoughagePhysicalSiloMD
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public System.Guid RoughagePhysicalSiloTypeId { get; set; }
[Required, DisplayName("Physical silo type")]
public string PhysicalSiloTypeName { get; set; }
public virtual ICollection<lutRoughagePhysicalSilo> lutRoughagePhysicalSiloes { get; set; }
}
}
}
what is a Buddy class suppose to mean?
Using both [Key] and the [DatabaseGenerated(DatabaseGeneratedOption.Identity)] should work and ignore any user provided value. After saving to the DB the property should have the DB generated Guid.
Your class lutConcentratePhysicalSiloType has no EF data annotations and if saved would take the values you provided. NewSequentialId() is a default and without any EF data annotations the DB row will get whatever the value you specify in the C# class.
I'm all new to databases and I've heard that SQLite should be straight forward, but I kinda find that not to be the case.
I have a decent knowledge of C# and WPF and I'm trying to make a small personal project which I want to use in daily life. My idea is a program that manages receipts that I bring home.
I have two Models - Item and Receipt
class Item
{
public int Id { get; set; }
public string Name { get; set; }
public double Price { get; set; }
public int ReceiptId { get; set; }
}
class Receipt
{
public int Id { get; set; }
public string Store { get; set; }
public double Price { get; set; }
public DateTime Date { get; set; }
}
My corrent problem is that I've been caught in all the different SQLite "versions" available. I've found that there is ADO.NET and LINQ and some other sorts.. what does these different ones mean and is the programming syntax for each of them different and which would be most suitable for my case?
I'm developing in Visual Studio 2012 and I've managed to download the NuGet SQLite package that goes by the name "System.Data.SQLite (x86/x64)".
I want to create a database, create two tables with these object in them, but I have basicly no idea how to and searching google for a day or two has just me that more confused, since so many people use different syntaxes and most of the tutorials I've find relate to how people used the old "SQLite.dll". So what my question is, is how do I make a database that fits this program structure and how do I write, read, connect and disconnect to my database.
I am struggling with returning a complex type from my services layer. It doesnt seem to be accessible from my object context.
This is the query in the service layer. All compiling fine.
public IQueryable<USP_GetPostsByThreadID_Result> uspGetPostsByThreadID(int ThreadID)
{
return this.ObjectContext.USP_GetPostsByThreadID(ThreadID).AsQueryable();
}
When I try and call it from my client, the ForumContext is not seeing it. I checked the client generated file and nothing similar is being generated. Help!!!
The name of your method may not meet the expected convention for queries. Try one or both of the following:
Add the [Query] attribute
Rename the method to GetUspPostsByThreadID
Result:
[System.ServiceModel.DomainServices.Server.Query]
public IQueryable<USP_GetPostsByThreadID_Result> GetUspPostsByThreadID(int ThreadID)
{
return this.ObjectContext.USP_GetPostsByThreadID(ThreadID).AsQueryable();
}
Its very common to have a stored procedure returning data from multiple tables. The return type doesn't fit well under any of the Entity Types(Tables). Therefore if we define Complex Type as the return collection of objects from Stored Procedure invocation, it becomes quite a powerful tool for the developer.
Following these steps I have achieved successfully the configuration of complex type on a sample AdventureWorks database.
1. Refer the picture and ensure the Stored procedure and function import is done.
2. Add the Domain Service name it as AdventureDomainService.
3. Now its time to define the tell the RIA services framework to identify my Complex Type as Entity Type. To be able to do this, we need to identify a [Key] DataAnnotation. Entity types provide data structure to the application's data model and by design, each entity type is required to define a unique entity key. We can define key on one property or a set of properties in metadata class file AdventureDomainService.metadata.cs
First define the class then add MetadatatypeAttribute like :
[MetadataTypeAttribute(typeof(CTEmployeeManagers.CTEmployeeManagersMetadata))]
public partial class CTEmployeeManagers
{
internal sealed class CTEmployeeManagersMetadata
{
private CTEmployeeManagersMetadata() { }
[Key]
public int EmployeeID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public int ManagerID { get; set; }
public string ManagerFirstName { get; set; }
public string ManagerLastName { get; set; }
}
}
Define the Domain service method to return the collection of objects/entities for populating the Silverlight Grid or any other data consuming controls.
public IQueryable<CTEmployeeManagers> GetEmployeeManagers(int empId)
{
return this.ObjectContext.GetEmployeeManagers(empId).AsQueryable();
}
We define IQueryable if we are to fetch the records from datasources like SQL, whereas we define IEnumerable if we are to fetch the records from in memory collections,dictionaty,arrays.lists, etc.
Compile the server side to generate the client proxy.
In the Silverlight side open the MainPage.xaml or wherever the datagrid is put, then add following namespaces :
using System.ServiceModel.DomainServices.Client;
using SLBusinessApplication.Web;
using SLBusinessApplication.Web.Services;
..
Load the data and display:
public partial class MyPage : Page
{
AdventureDomainContext ctx = new AdventureDomainContext();
public MyPage()
{
InitializeComponent();
LoadOperation loadOp = this.ctx.Load(this.ctx.GetEmployeeManagersQuery(29));
myGrid.ItemsSource = loadOp.Entities;
}
// Executes when the user navigates to this page.
protected override void OnNavigatedTo(NavigationEventArgs e)
{
}
}
That is all that is needed to do.
It has to be part of an entity. Complex types cannot be returned by themselves