MVC: Get List of values from Database - asp.net-mvc

I am trying to pull data from my database in my MVC Controller. This is the code I have but not sure if I'm doing this right using a LINQ query
public class EditProfileController : Controller
{
private ApplicationDbContext db = new ApplicationDbContext();
public IActionResult Index()
{
var listdata = db.Users.ToList().Select(x => new FE.Models.AspNetUsers
{
Id = x.Id,
// (repeat the same for all)
}).ToList();
}
}
Get error on Index:
EditProfileController.Index(): not all code paths return a value FE
and on db:
The name db does not exist in the current context
How can I pull data from a database table to create a list view? Should I use LINQ and if so what am I missing from my code above?

You are not returning anything you should return your list:
public class EditProfileController : Controller
{
public IActionResult Index()
{
var listdata = db.Users.ToList().Select(x => new FE.Models.AspNetUsers
{
Id = x.Id,
// (repeat the same for all)
}).ToList();
return Ok(listdata);
}
}

public class EditProfileController : Controller
{
public IActionResult Index()
{
List<FE.Models.AspNetUsers> listdata = new List<FE.Models.AspNetUsers>();
using(ApplicationDbContext db = new ApplicationDbContext())
{
listdata = db.Users.Select(x => new FE.Models.AspNetUsers
{
Id = x.Id,
// (repeat the same for all)
}).ToList();
}
return View(listdata)
}
}
I made a couple assumptions that you are trying to pass the list to a view rather than returning the list of AspNetUsers and your db context is working. Make sure in your view you declare the model like so:
#model IEnumerable<FE.Models.AspNetUsers>

I only work with VB (use C# converter) so here is how I get get a list of values from my DB:
Public Function Index()
dim listData as List(Of Users) = new List(Of Users)
Using db as new YourDB()
listData = db.Users.Select(Function(x) x.Id = id).ToList()
End Using
return listdata
End Function
Or you can just use an IQueryable of your model.

Related

getting all rows from db mvc asp.net

var listdata = db.UserDetails.Select(m => new SelectListItem
{
Value = m.userid.ToString(),
Text = string.Format("{0}{1}{2}{3}",m.bankname,m.userid,m.gender,m.name)
});
Here UserDetails is the table that is present in the database and this is the way i am trying to display every entry of the table.
Controller
[HttpGet]
public ActionResult getAll()
{
var listdata = db.UserDetails.Select(m => new SelectListItem
{
Value = m.userid.ToString(),
Text = string.Format("{0}{1}{2}{3}",m.bankname,m.userid,m.gender,m.name)
});
return View("getAll", listdata);
}
View
#model UserApp.Models.UserDetails
#{
ViewBag.Title = "getAll";
}
<h2>getAll</h2>
#foreach (var item in Model)
{
<tr>
<td>
#Html.DisplayFor(modelItem => item.name)
</td>
<td>
#Html.DisplayFor(modelItem => item.gender)
</td>
</tr>
}
Model
namespace UserApp.Models
{
public class UserModel : IEnumerable<UserModel>
{
public int userid {get; set;}
public string name{get; set;}
public IList<SelectListItem> bankname { get; set; }
public string gender{get; set;}
}
}
How do i get the elements and display them properly on the view?
I can't seem to get a proper solution.
Stuck on this thing for hours.
P.s: new to it, any help will be appreciated.
First, add ToList() for your listdata to make it list, currently it is still IQueryable , second your view accepts model, you are passing list of model, I guess you want that to be list not model, something like this
#model List<UserApp.Models.UserDetails>
Third, you are selecting SelectListItem but you are using UserApp.Models.UserDetails, I think you should be doing something like this
var listdata = db.UserDetails.ToList().Select(x => new UserApp.Models.UserDetails {
userid = x.userid, (repeat the same for all)
}).ToList();
because looking at your code you don't need selectListItem, you need UserApp.Models.UserDetails.
That should fix all your problems, I hope I didn't miss any.
My approach may not be the best approach but it seems to work for me.
I usually have my model for the item :
model :
namespace UserApp.Models
{
public class UserModel
{
public int userid {get; set;}
public string name{get; set;}
public IList<SelectListItem> bankname { get; set; }
public string gender{get; set;}
}
}
Then I have in my database class ( a class that calls the database and populates the queries etc: Call it CodeDB() for this example)
DB getter :
public List<UserModel> getUsers(){
{
List<UserModel> myUsers = new List<userModel>();
// however you are accessing your db do it here
string sql = "select * ...";
//access DB
//open connection
//run query command usually for me it is rdr = cmd.ExecuteReader();
while(rdr.Read()){
UserModel retrievedUser = new UserModel();
retrievedUser.userid = (int)rdr[0];
retrievedUser.name = rdr[1].ToString();
... add the other fields
myUsers.Add(retrievedUser);
}
//close db connection
return myUsers
}
In my Controller
//call my database class
CodeDB() DB = new CodeDB()
[HttpGet]
public ActionResult getAll()
{
List<UserModel> viewUsers = DB.getUsers();
ViewBag.users = viewUsers
return View();
}
in the view
#{
if(Viewbag.users != null)
{
foreach(UserApp.Models.UserModel u in ViewBag.users)
{
#Html.Raw( " userID : " + u.userid +" Gender : " + u.gender)
}
}
}
I think you could do. MVC Scaffolding of Crud with there Views Auto Generated
When you make your controller There's an option "MVC Controller with Views"
Then it will ask For your Model that you want to use for scaffolding which will be
"UserModel" Then just give your Controller a Name.
Now if you look at the Index View of your Controller it will have all the attributes you want and don't want.But of course, you can remove the unnecessary attributes
Hope this helps!

Returning more than just one model to the View?

I am fairly new to MVC, and I've been reading a bit about ViewModels, but how do I go about sending two models to my View, where the queries are like so
public ActionResult Index(int Id)
{
var People = from a in db.Person
select a;
var Data = from a in db.Member
where a.Person.PersonId.Equals(Id)
select new
{
a.Project.ProjectId,
a.Project.Name,
a.Project.Customer,
a.Project.TechProfile.Select(x => new
{
x.TechId,
x.Name,
x.Elements
}),
a.MemberId,
a.Role,
a.Start,
a.End
};
return View(People);
}
I was using #model IQueryable<GeoCV.Models.Person> before so I could use a #foreach in my View but I don't know how to get my other query to the View so I can get data from it too.
Update
And I'm making a custom class for my Data query, but I don't know how to set the property of TechProfile
Right now I have
public IEnumerable<TechProfile> ProjectTechProfile { get; set; }
In my custom class, but it doesn't work, so I guess I have to specify TechId, Name and Elements?
But how?
A ViewModel wraps around the 2 models you are getting with your 2 queries, so you can return it as a single object to your view. In your case we need to adress another issue first. You are returning an anonymous object in your data query.
This means, your data query needs to return a strongly typed object instead of an anonymous object.
Create a class for your data query:
public class MyCustomDataObject
{
public int ProjectId { get; set; }
//... map all properties as needed
}
then edit your data query to return this object:
var Data = from a in db.Member
where a.Person.PersonId.Equals(Id)
select new MyCustomDataObject
{
ProjectId = a.Project.ProjectId,
//assign all properties
};
Now you need to create the actual ViewModel class:
public class MyViewModel
{
public IEnumerable<Person> Persons { get; set; }
public IEnumerable<MyCustomDataObject> Data { get; set; }
}
And after this you just need to assign the values to it in your Actionmethod:
public ActionResult Index(int Id)
{
var People = from a in db.Person
select a;
var Data = from a in db.Member
where a.Person.PersonId.Equals(Id)
select new MyCustomDataObject
{
ProjectId = a.Project.ProjectId,
//...
};
//store data of both queries in your ViewModel class here:
var vm = new MyCustomDataObject();
vm.Persons = People;
vm.Data = Data
//return ViewModel to View.
return View(vm);
}
And then declare it in your view: #model Namespace.Subfolder.MyCustomDataObject
You can use #Html.Action("actionName","controllerName") method in view. You can divide your original view into multiple partial view and then you can render that partial view with dynamic model binding using #Html.Action("actionName","controllerName") method.
For more details with sample code http://devproconnections.com/development/how-use-aspnet-mvc-render-action-helpers
You can have methods like below to get multiple model in single view
private IList<People> GetPeople()
{
return from a in db.Person
select a;
}
private IList<Data> GetData()
{
return from a in db.Member
where a.Person.PersonId.Equals(Id)
select new
{
a.Project.ProjectId,
a.Project.Name,
a.Project.Customer,
a.Project.TechProfile.Select(x => new
{
x.TechId,
x.Name,
x.Elements
}),
a.MemberId,
a.Role,
a.Start,
a.End
};
}
public ActionResult Index(int Id)
{
var MultipleModel = new Tuple<IList<People>,IList<Data>>(GetPeople(),GetData()) { };
return View(MultipleModel);
}
Here's a codeproject tutorial on the subject.

MVC 5 DropDownListFor Database Linq;

Can anyone please tell me how to write Controller for C# (public ActionResult DropList()) for Drop Down List generate Linq I want convert this SELECT DISTINCT CouName FROM Locations; to Linq for my drop down list dynamically generate.
Chtml page how do I write in #Html.DropDownListFor("")
Models.Location
This code will generate a select list from an IQueryable GetAll() method, or you could use it on your entity directly using from c in _context.Set<Location>()
public SelectList GetAsSelectList()
{
var locs = from c in GetAll()
select new
{
Id = c.Id,
Name = c.Name
};
return new SelectList(locs, "Id", "Name");
}
Where Id is the Value field and Name is the Text field of the selectlist options.
This would be assigned to a model property:
var model = new MyModel
{
LocationList = GetAsSelectList();
}
You would pass the model to your View, and use DropDownListFor:
#Html.DropDownListFor(x => x.MyModel.Location, Model.LocationList)
Your model would also have a Location property which you would set to display a default value if you wanted to do that.
Assuming you model is named MyModel
Controller
public ActionResult Edit()
{
var couriers = // get your couriers from the database using your query
// Is better to assign this to a property in your view model, but ViewBag will do for now
ViewBag.CourierList = new SelectList(couriers);
var model = new YourModel();
}
View
#model YourModel
#using(Html.BeginForm())
{
#Html.DropDownListFor(m => m.CouriersName, (SelectList)ViewBag.CourierList)
}
As far as i have understood, you can do something like this:
public ActionResult DropList()
{
List<SelectListItem> objResult = new List<SelectListItem>();
var result = dbContext.Locations.Select(x=>x.CouName).Distinct().ToList();
foreach(var item in result)
{
SelectListItem temp = new SelectListItem();
temp.Text = item;
temp.Value = item;
objResult.Add(temp);
}
ViewBag.DropdownResult = objResult;
return View();
}
Dropdown in view:
#Html.DropDownListFor(m=>m.ModelLocations, ViewBag.DropdownResult as List<SelectListItem>)
Please modify the code as per your need.
using System.Web.Mvc;
...
public static List<SelectListItem> GetItemsForDisplay(string listName)
{
//your data access function should return a list of objects
return DAL.Table.SelectByName(listName)
.Select(x=> new SelectListItem{Text=x.DisplayName, Value=x.ID})
.ToList<SelectListItem>();
}

How to create a DropDownList from a LINQ query

I'm trying to use the results of a LINQ query to create a dropdownlist in an MVC app. I'm using this answer as a reference. However, when I try to implement for my case I get the error: 'System.String' does not contain a property with the name 'SAMPLING_EVENT'
My code is as follows:
Controller
public class HomeController : Controller
{
//
// GET: /Home/
public ActionResult Index()
{
ViewBag.Title = "Sample Tracker Tool";
DateTime nineMonthsAgo = DateTime.Now.AddDays(-270);
var context = new EDMS_Entities();
var resultSet = (from samplingEvents in context.EDMS_SAMPLES
where samplingEvents.RECORD_CREATED_DATE >= nineMonthsAgo
orderby samplingEvents.SAMPLING_EVENT
select samplingEvents.SAMPLE_ID)
.Distinct();
var viewModel = new SamplingEventsVM();
viewModel.SamplingEvents = new SelectList(resultSet, "SAMPLING_EVENT", "SAMPLING_EVENT");
return View(viewModel);
}
}
ViewModel class
public class SamplingEventsVM
{
public int SelectedSamplingEvent { get; set; }
public SelectList SamplingEvents { get; set; }
}
View
#model SamplingEventsVM
<h2>#ViewBag.Title</h2>
<span>
#Html.DropDownListFor(model => model.SelectedSamplingEvent, Model.SamplingEvents, "Sampling Event")
</span>
What am I doing wrong?
You are selecting this select samplingEvents.SAMPLE_ID
So you get a List of int maybe, depends on your ID type
Then you try to make a select list with the property value "SAMPLING_EVENT"
Which doesn't exist on the int object you filled resultSet with.
Instead do this:
var resultSet = (from samplingEvents in context.EDMS_SAMPLES
where samplingEvents.RECORD_CREATED_DATE >= nineMonthsAgo
orderby samplingEvents.SAMPLING_EVENT
select samplingEvents)
.Distinct();

With Repository pattern, what is the most effective way of updating records?

I am implementing Repository Pattern with ADO.NET entity framework. I see that updating records is relatively more complicated than just adding or removing from the database. See below the Update statement and add statement for your judgment.
I was wondering if there is any way that I can update the record without having to retreive the original record first.
public void Update(User user)
{
var userToUpdate = (from u in db.UserSet
where u.UserID == user.UserID
select u).FirstOrDefault(); //original record
db.ApplyPropertyChanges(userToUpdate.EntityKey.EntitySetName,
user);
db.SaveChanges();
}
Add statement for the same repo:
public void Add(User user)
{
user.MemberFrom = DateTime.Now;
_repository.AddToUserSet(user);
_repository.SaveChanges();
}
No, you can't do that with EF (unless you use ADO.NET directly of course). That said, you can simplify the retrieval code by adding some methods to the partial class of your entity context. This is how I do it:
public partial class MyEntities
{
public T GetById<T>(object id) where T : class
{
EntityKey key = CreateKey<T>(id);
// see http://msdn.microsoft.com/en-us/library/system.data.objects.objectcontext.getobjectbykey.aspx
return (T)GetObjectByKey(key);
}
public static EntityKey CreateKey<T>(object id)
{
var type = typeof(T);
return new EntityKey("MyEntities." + type.Name, "Id", id);
}
}
Now, your above code should be
public void Update(User user)
{
var userToUpdate = db.GetById<UserSet>(user.UserID);
db.ApplyPropertyChanges(userToUpdate.EntityKey.EntitySetName, user);
db.SaveChanges();
}

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