Develop Reference

Entity Framework, how to make this more generic to write less code

So, I am writing a program, and getting my data using EF 6.
Basically, I though the simplest approach would be to have one class like this:
public class DataRetriever
{
public List<TEntity> GetAll<TEntity>() where TEntity : class
{
using (var Db = new Entity())
{
return Db.Set<TEntity>().ToList();
}
}
}
So then, you care start creating other classes on the basis of specifying which data you want to be collected. So say I have a list of carnival rides and one method is to get a single ride or something. SO then I would have the following:
public class SelectedRide
{
int RideId { get; set; }
string RideName { get; set; }
string DomValue { get; set; }
public SelectedRide(DataRetriever Retriever)
{
var Records = Retriever.GetAll<vwRideList>();
var Record = from x in Records
where x.RideId == RideId
select x;
RideName = Record.Single().RideName;
DomValue = Record.Single().DomValue;
}
}
Ride ID being an identity.
So then one could say that if another class like say we had multiple parks where rides were, could be public class SelectedPark it would have the same logic, but in the Retriever.GetAll<vwParkList>(); The ride list is now the park list. And so on.
I can't tell if this is quickly going to get out of hand if I say had 50 separate types of retrieving that needed to be done. Granted, I won't as I know the total scope of this program, but WHAT IF.
I've seen stuff like the repo pattern as well, but I can't tell if that's somewhat of a waste of time or not. I can't tell what I am getting out of it. This seemed to keep it generic enough that I am not writing the context in a million different places.

DevExpress Datagrid Master-Detail Multiple List<type> as a Datasource - Guidance

My program gets two lists of custom types. The first list is the master and contain a schedule, the second list is the detail and contains the actions taken against the master list.
I am trying to apply these binding lists to a DevExpress Grid Control in a Windows Form with the above mentioned relationship (Master-detail), but I am stumped by how to do this. The examples and walk-troughs I have read use ADO datasets.
I imagine I would have to take the two lists and program a relationship in some kind of dataset file and link this to the grid, but I must admit I haven't a clue. Any guidance welcome.
Thanks :)
P.S. I should mention, I have successfully bound the master view to a list, but my trouble comes when I try to bind the detail view to a data source. It seems to me that the data source will only accept one binding source and the binding source will only accept one binding list.

The GridControl is smart enough to detect a master-detail relation based directly on data-type:
gridControl1.DataSource = new List<Blog> {
new Blog {
Url = "http://blogs.msdn.com/adonet",
Posts = new List<Post>{
new Post() { Title = "The First" },
new Post() { Title = "The Second" }
}
}
};
The relation is defined onto the Blog class level via List-property:
public class Blog {
public string Url { get; set; }
public List<Post> Posts { get; set; } // <<<
}
public class Post {
public string Title { get; set; }
public string Content { get; set; }
}

How do I add a new table to a Telerik Open Access MVC project?

I've inherited a MVC project that seems to use Telerik Open Access to handle data instead of using something I'm more familiar with like entity framework. I'm trying to understand the whole concept of how to work with this data method, but right now I'm just needing to find out how to add a table. I've limited my code examples to one table, but in reality there are dozens of them.
So I see that the class OpenAccessContext.cs has a database connection string, but it also has a IQueryable item made up of the class tblMaterial. The tblMaterial class is defined in tblMaterial.cs. I don't understand how this class is connected to the SQL database version of tblMaterial (so feel free to educate me on that).
I have a table called tblContacts in the SQL database. What do I need to do to connect it to my project? There's no "update from database" option when I right click any object in the solution (because they're all just classes). Will I need to create a new class manually called tblContacts.cs? If so, how do I connect it to the database version of tblContacts? Am I going to need to manually change multiple classes to add the table (OpenAccessContext, MetadataSources, Repository, etc.)?
I tried to keep this as one simple question (how do I add a table) so I don't get dinged, but any light you can shine on the Telerik Open Access would be helpful. (Please don't ding me for asking that!) I checked out the Telerik documentation here: http://docs.telerik.com/data-access/developers-guide/code-only-mapping/getting-started/fluent-mapping-getting-started-fluent-mapping-api , but it's related to setting up a new open access solution. I need to know how to modify one (without ruining the already working code). Thank you in advance for your help!
Here's the solution as seen in Visual Studio:
Open Access
Properties
References
OpenAccessContext.cs
OpenAccessMetadataSources.cs
Repository.cs
tblMaterial.cs
Here's the code:
OpenAccessContext.cs
namespace OpenAccess
{
public partial class OpenAccessContext : OpenAccessContext
{
static MetadataContainer metadataContainer = new OpenAccessMetadataSource().GetModel();
static BackendConfiguration backendConfiguration = new BackendConfiguration()
{
Backend = "mssql"
};
private static string DbConnection = ConfigurationManager.ConnectionStrings["ConnString"].ConnectionString;
private static int entity = ConfigurationManager.AppSettings["Entity"] == "" ? 0 : int.Parse(ConfigurationManager.AppSettings["Entity"]);
public OpenAccessContext() : base(DbConnection, backendConfiguration, metadataContainer)
{
}
public IQueryable<tblMaterial> tblMaterials
{
get
{
return this.GetAll<tblMaterial>(); //.Where(a => a.EntityId == entity);
}
}
}
}
OpenAccessMetadataSources.cs
namespace OpenAccess
{
public class OpenAccessMetadataSource : FluentMetadataSource
{
protected override IList<MappingConfiguration> PrepareMapping()
{
var configurations = new List<MappingConfiguration>();
// tblMaterial
var materialConfiguration = new MappingConfiguration<tblMaterial>();
materialConfiguration.MapType(x => new
{
MaterialId = x.MaterialId,
MaterialName = x.MaterialName,
MaterialDescription = x.MaterialDescription,
MaterialActive = x.MaterialActive,
MaterialUsageType = x.MaterialUsageType,
AddDate = x.AddDate,
AddBy = x.AddBy,
ModDate = x.ModDate,
ModBy = x.ModBy
}).ToTable("tblMaterial");
materialConfiguration.HasProperty(x => x.MaterialId).IsIdentity(KeyGenerator.Autoinc);
}
}
}
Repository.cs
namespace OpenAccess
{
public class Repository : IRepository
{
#region private variables
private static OpenAccessContext dat = null;
#endregion private varibles
#region public constructor
/// <summary>
/// Constructor
/// </summary>
public Repository()
{
if (dat == null)
{
dat = new OpenAccessContext();
}
}
#endregion public constructor
#region Material (tblMaterials)
public int CreateMaterial(tblMaterial itm)
{
try
{
dat.Add(itm);
dat.SaveChanges();
return itm.MaterialId;
}
catch (Exception)
{
return 0;
}
}
}
}
tblMaterial.cs
namespace OpenAccess
{
public class tblMaterial
{
public int MaterialId { get; set; }
public string MaterialName { get; set; }
public string MaterialDescription { get; set; }
public bool MaterialActive { get; set; }
public int MaterialUsageType { get; set; }
public DateTime? AddDate { get; set; }
public string AddBy { get; set; }
public DateTime? ModDate { get; set; }
public string ModBy { get; set; }
}
}

In the case of tblContacts, I would suggest to you the following workflow for extending the model:
Add a new class file that will hold the definition of the tblContact POCO class. In this class add properties that will correspond to the columns of the table. The types of the properties should logically match the datatypes of the table columns.
In the OpenAccessMetadataSource class, add a new MappingConfiguration<tblContact> for the tblContact class and using explicit mapping provide the mapping details that logically connect the tblContact class with the tblContacts table. Make sure to add both the existing and the new mapping configurations to the configurations list.
Expose the newly added class through an IQueryable<tblContact> property in the context. This property will allow you to compose LINQ queries against the tblContacts table.
Regarding the Repository class, it seems like it is related to the custom logic of the application. It surely is not a file generated by Data Access. Therefore, you need to discuss it in your team.
I also strongly advise you against using OpenAccess in the namespaces of your application. This is known to interfere with the Data Access' namespaces during build time and at some point it causes runtime errors.
I hope this helps.

C# Complex Property Setter option

I have an ASP.Net MVC 5 (C#) application and I'm giving my users the ability to like posts and comments.
for this I have a Model called Likes with the following Properties:
public class Like
{
public Like()
{
this.CreatedUTC = System.DateTime.UtcNow;
this.isActive = true;
}
public long id { get; set; }
public string UserID { get; set; }
public bool isActive { get; set; }
public LikeType Type { get; set; }
public DateTime CreatedUTC { get; set; }
}
Type is an enum and it can be either Comments or Posts. I've also added the following Navigation Property to both Post Model and Comment Model:
public virtual ICollection<Like> Likes { get; set; }
My question is, can I have a setter function in the above line of code where it would automatically set Comments and Posts for the Like type? I know I can use the Value variable in the Setter but using Google I couldn't find how to use it for complex types as I have above (Like).
I'm sure this would be a better way of doing this than in the repository manually set that enum every-time I'm going to save a like.
UPDATE:
Seeing how we're starting a nice little conversation about this Questions, I will throw another alternative in the mix.
How about two Tables with a base class of Like, one CommentLikes and the other PostLikes Seeing that the size of this table will grow really fast, I'm thinking separating them would possibly be a good thing, Right?

I'd rather drop the "LikeType" and either have Comment and Post entity in the Like entity and distinguish by one of them being null or introduce two new entities
public class CommentLike
{
public Comment Comment { get; set; }
public Like Like { get; set; }
}
which holds a comment and a like and PostLike which holds a Post and a Like. The Comment then looks like this
public Comment
{
public virtual ICollection<CommentLike> { get; set; }
}
Another alternative is to create separate tables for comment and post likes. While what you ask for is definitely doable I would recommend more verbose but simpler solution which will result in code that is easier to maintain and has less bugs. Is there any specific reason you want to have a LikeType property?

I had same problem but didnt encounter an easy way.
class Post{
public virtual ICollection<Like> Likes {set;get;}
}
class Comment{
public virtual ICollection<Like> Likes {set;get;}
}
Then:
class Like{
//....
}
You dont need a bi-directional relationship. Do you have a case where you need to query Likes table? and if you do, you will have to manage parsing it as ENUM somewhere which can be an extension method.
EF will create Post_Id and Comment_Id implicityly in your table design. You wont be able to query it but you wont need to. IN my experience i never needed to.

My question is, can I have a setter function in the above line of code
where it would automatically set Comments and Posts for the Like type?
I assume you are using T4 template or the classes that were generated by EF are partialthen you can extend it by creating another partial class and a wrapper property for Likes
// Backing field
private ICollection<Like> _likesWrapper;
public ICollection<Like> LikesWrapper {
get {
// Lazy loading
if(_likes == null)
{
// Just create a new list or load it from the database.
_likes = new List<Like>();
}
return _likes;
}
set {
foreach(var val in value)
{
//Set the comment and posts
}
Likes = value;
}

Custom organized data accessing via classes and constructors

struggling To achieve a solution for a basic Task:
working with more than one Sql Data table, as a source, for a WebSite application...
that's what leads me here once again... seeking for an Experienced C# .net Developers Help.
i was just trying to add some basic logic for a proper implementation,Like using
a dedicated namespace & classes, To Hold reference for All DATABASE tables,
(before i try working / learning about Entities Framework approach.)
i would like to try implement same of basic features of EF ...by my self, and that way... i will also learn how to properly work with classes.
as it is so far ... structured : with my little knowledge
a 'helper'.. namespace , say the company name is: HT technologies
so I've named the namespace HT_DbSchema ...that contains :
tables names
public sealed class HTDB_Tables
{
public const string Customers= "Customers";
public const string Times= "Times";
}
tables IDs
public sealed class HT_tblIDs
{
public const int tblCustomersID = 1, tblTimesID = 2;
}
tables Columns Lists ...(just one example)
public class HTDB_Cols
{
public class tblCustomers
{
public const string CustId = "custId",
CustName = "custName",
CellPhone = "cellPhone" .... etc'
}
}
and as all those 3 classes are serving all projects ..
there's another helper class for constructor Per Table For the Current Project
public class DBMetaDetails
{
public struct DbTable
{
public string TableName { get; set; }
public int TableID { get; set; }
}
}
so still these are all construction / helpers Classes and are separated from the project,
now for current project
What is The Appropriate way to get it done, using above Classes and constructor within a project
(i could name those templates)
what i was doing so far to implement some order is :
protected void Page_Load(object sender, EventArgs e)
{
if(!Page.IsPostBack)
{
.... some other App inits here
}
else
{
}
// this method should be the one that instanciates the DbTable struct
//and set the values of tables name and "ID"
setTablesReferences();
}
And Here's where the confusion starts :
in a day by day usage i want to try implement it in a WebSite application :
public void setTableReferences()
{
DBMetaDetails.DbTable CustMeta = new DBMetaDetails.DbTable();
DBMetaDetails.DbTable TimesMeta = new DBMetaDetails.DbTable();
}
so now i need to set CustMeta & TimesMeta details(ids & names)
the struct has a kind of a template structure a kind'a systematic technique to initialize and assign values, so it brings some decent order to my logic with it's existence .
so what is the confusing part ?
from one point of view(safety), i need those tables detailes to be readonly
so DbTable.TableID, and DbTable.TableName would not get overWriten by mistake.
having said that, there should be only one place it could be SET ... a dedicated section of the application, like setTableReferences() above,... there i might add :
CustMeta.TableID = HT_tblIDs.tblCustomersID
CustMeta.TableName = HTDB_Tables.Customers;
on the other hand, i need the information of the tables to be Accessible,
so if let's say i would like to add those DataTables into a DataSet
DataSet ALLTablesSet = new DataSet();
// assuming the SQL actions already been taken in another method previosly...
// so DataTable is already retrived from DB
//...but only as a short usage example:
AllTablesSet.Tables.Add(new DataTable(CustMeta.TableName));
My Question is What is the Correct Way to work with structs ... as in My Scenario,
So in one section of app: you would initialize - assign it with a value privately.
and from other sections of the app you could use its value (Only For Readings)
so that way, the application will not be able to access it's value for writing,
only by reading values, i think it should be trough another (Public ReadOnly) Variable.
so that variable was meant to be exposed ...and it's value could not be "harmed"

If I understand the question correctly, the way I would prevent other code from modifying it is by removing the setters on the properties. However, you still need to set them at some point, so rather than removing the setters completely, you can just make them private. For example:
public string TableName { get; private set; }
If you do this, the only place you can set this data is within the struct itself, so you would need to create a constructor that took the initial values you wanted. So something like:
public struct DbTable
{
public DbTable(string tableName, int tableId)
{
this.TableName = tableName;
this.TableID = tableId;
}
public string TableName { get; private set; }
public int TableID { get; private set; }
}