I'm attempting to create a drop down list from one table in my database grouped by names from a different table in the same database.
What I have is a table that holds a bunch of units. These units belong to parent units. The tables are joined on the parent units id. So for the Units table, there's a property Parent, data type int. The ParentUnit table has an Id data type int, and a Name.
What I want to do is create a drop down list with all the Units group together by the Parent's Name. Unfortunately, this needs to happen inside the Controller and NOT the Model.
The other peace is, the drop down list is part of a workorder request form. So in the Workorder Controller, I need to create a SelectList with the optionGroup of Name of the Parent Unit.
How do I go about doing this?
This is what I'm thinking:
ViewBag.UnitId = new SelectList(db.Units.ToList(), "Id", "Name", ParentUnit.Name);
but I don't know how to implement it since I'm new to MVC.
When I tried ViewBag.UnitId = new SelectList(db.Units.ToList(), "Id", "Name", "Parents", 1);, the IDs of the Parents showed up in the optGroup, I'm guessing because the Id of the ParentUnit is stored in the Units table. How can I get the Name of the Parent to show up?
Based on my experience, First, it's better to change your model,
So you can have both tables (models) in one model with self-relation, for example, your model can be:
public class Model_Name
{
public int Id { get; set; }
public string Title { get; set; }
public int ParentId { get; set; }
public Model_Name model_name { get; set; }
public ICollection<Model_Name> Model_Names{ get; set; }
}
And then implement your view model layer (DTO) as below;
public class View_Model_Name
{
public int Id {get;set;}
public string Title {get;set;}
public int ParentId {get;set;}
public int ParentTitle {get;set;}
}
Then for the implementation option group, you need to get a Dictionary of data, same as below:
public Dictionary<long,List<View_Model_Name>> GetGroupAndChilds()
{
var result = _yourcontext.Model_Name
.Select(x => new View_Model_Name
{
ID = x.ID,
Title = x.Title,
ParentId = x.ParentId,
ParentTitle=x.Model_Names.Title,
}).AsEnumerable().GroupBy(x => x.ParentId).ToList();
return result.ToDictionary(k => k.Key, v => v.ToList());
}
Now you have a list of your data and you can use it in the presentation layer (Razor Page) as below:
public List<SelectListItem> showlist = new List<SelectListItem>();
public List<SelectListItem> GetList()
{
var allList= GetGroupAndChilds();
foreach (var (key, value) in allList)
{
var parentTitle = GetDetails(key).Title; //you can write a function to get title from Id
var group = new SelectListGroup() { Name = parentTitle };
foreach (var per in value)
{
var item = new SelectListItem(per.Title, per.ID.ToString())
{
Group = group
};
showlist.Add(item);
}
}
And finally, add the below tag to your cshtml (view) page;
<select asp-for="Your_Page_Model.YourItem" asp-items="Model.showlist"></select>
Finish
Related
public static List<TruckWithModel> GetAllTrucks()
{
using (DAD_BaldipContext ctx = new DAD_BaldipContext())
{
var x = ctx.TruckFeatureAssociation
.Include(t => t.Truck)
.Include(tf => tf.Feature)
.Include(tm => tm.Truck.TruckModel)
.Select(it => new TruckWithModel()
{
Colour = it.Truck.Colour,
Size = it.Truck.TruckModel.Size,
RentalPrice = it.Truck.DailyRentalPrice,
Status = it.Truck.Status,
Model = it.Truck.TruckModel.Model,
Rego = it.Truck.RegistrationNumber,
Features = it.Feature.Description
}) ;
return (List<TruckWithModel>)x.ToList();
}
}
This code retrieves the various attribute values from the relative tables TruckFeatureAssociation, TruckFeature, IndividualTruck and TruckModel.
The trouble I'm having is that the TruckFeatureAssociation has up to 5 entries for the same truck, this table is a junction table between IndividualTruck and TruckFeature where TruckFeature is a table of various features.
For each TruckFeatureAssociation a different object of TruckWithModel is created i.e. if there are 3 features associated each truck has three rows displayed in the datagrid where I call this function.
I want it so that all the features can be stored in one object.
So in the above output I would want, only one row, saying alarm systems, chrome wheels.
The issue here is that you are querying against Features, but the model reflects a Truck... Query a truck, get it's features, then let your view model (TruckWithModel) help format that data for the view..
For example:
[Serializable]
public class TruckWithModel
{
public string Colour { get; set; }
public string Size { get; set; }
public decimal RentalPrice { get; set; }
public string Status { get; set; }
public string Model { get; set; }
public List<string> Features { get; set; } = new List<string>();
public string FormattedFeatures
{
get { return string.Join(", ", Features); }
}
}
Now when you query the data:
var trucks = ctx.Trucks
.Select(t => new TruckWithModel()
{
Colour = t.Colour,
Size = t.TruckModel.Size,
RentalPrice = t.DailyRentalPrice,
Status = t.Status,
Model = t.TruckModel.Model,
Rego = t.RegistrationNumber,
Features = t.Features.Select(f => f.Description).ToList()
}).ToList();
This assumes that Truck has a Collection of Features where TruckFeatureAssociation is just a mapping entity. If your Truck's collection is based off TruckFeatureAssociation:
Features = t.Features.Select(f => f.Feature.Description).ToList()
Now in your view, where you want to display the features, bind to the FormattedFeatures property to get the comma-delimited list of Features for each Truck.
Note that when you use Projection through .Select() you do not need to use .Include() to eager load related entities. EF can work out what to load to satisfy the projection automatically.
I have a ViewModel
public class ProductViewModel
{
public ProductModel Product { get; set; }
public string ProductVersion { get; set; }
public UserModel User { get; set; }
...
}
I query the database and fetch a Dataset which has one table say Table[0] that has- many rows- a list of details of all the members of my ViewModel (i.e. Product,ProductVersion,User)
My db query is as below
SELECT productName,
productID,
productPrice,
...
PRODUCTVerion,
UserName,
UserID,
UserEmail
FROM Product,
ProductVersionCtrl,
User
...
The return type of my method is
IEnumnerable of ProductViewModel
<>
My Requirement I need a lamda linq query that would frame\form the object IEnumnerable
of ProductViewModel
return type is given below
IEnumerable<ProductViewModel>
What I have tried
I have idea to place simple data which belongs to one complex object liek
IEnumerable<DealerModel> list = dsData.Tables[0].AsEnumerable().Select(p =>
new DealerModel()
{
DealerID = int.Parse(p["DealerID"].ToString()),
DealerName = p["DealerName"].ToString(),
DealerContactNo = p["DealerContactNo"].ToString(),
DealerEmailID = p["DealerEmailID"].ToString(),
DealerPassword = "******",
IsActive = int.Parse(p["IsActive"].ToString())
});
But I am not able to place different object within the ViewModel
Yes I got it , The below worked for me.
IEnumerable<ProductBuyViewModel> productBuyList = dsData.Tables[0].AsEnumerable().Select(p =>
new ProductBuyViewModel()
{
ProductBuy = {ProductName = p["productName "],ProductPrice =p["ProductPrice ...]},
ProductVesrion =p["ProductVesrion "],
User = {UserName =...}
});
I have the following Entity Data models, simplified for brevity;
public abstract class Entity<T> : BaseEntity, IEntity<T>
{
[Key]
public virtual T Id { get; set; }
}
public class User : Entity<int>
{
public List<Category> Categories { get; set; }
}
public class Category : Entity<int>
{
public string Description { get; set; }
}
public class List : Entity<int>
{
public Category Category { get; set; }
}
These are accessed from the DbContext using a DbContext exposed by either a generic service, or a more customised implementation to provide business logic.
When I publish the database and add the following code to the Seed() method, all is well and the data looks good directly in the database.
var user = new User
{
Email = "",
Categories = new List<Category>
{
new Category
{
Description = "Category 1",
},
new Category
{
Description = "Category 2",
}
}
};
context.Users.AddOrUpdate(u => u.Email, user);
var list = new List()
{
Id = 1,
Description = "Test List",
UserId = 1,
Category = user.Categories.FirstOrDefault()
};
context.Lists.AddOrUpdate(u =>u.Id, list);
Please note that the User owns the categories and you can (should only be able to) create them by accessing the Categories Property.
This gives me;
I am using these objects in my controller as such;
public ActionResult Edit(int id)
{
var categories = _usersService.GetUser(User.Id).Categories;
categories.Insert(0, new Category {Description = "", Id = 0});
var list = _listsService.GetList(id);
var viewModel = new EditViewModel
{
Id = list.Id,
Reference = list.Reference,
Description = list.Description,
CategoryId = list.Category?.Id ?? 0,
Categories = new SelectList(categories.AsEnumerable(), "Id", "Description")
};
return View(viewModel);
}
In the above test, I am using the List inserted during the Seed and I can see the List does indeed have a Category, and the values are correct.
For information, I am using the following ViewModel. I have been investigation methods to be able to 'select' the User.Categories from a DropDown and this appeared to work the best at present.
public class EditViewModel
{
[Required]
public int Id { get; set; }
[Required]
public string Description { get; set; }
public IEnumerable<SelectListItem> Categories { get; set; }
[ScaffoldColumn(false)]
public int CategoryId { get; set; }
[ScaffoldColumn(false)]
public Guid Reference { get; set; }
}
The populated ViewModel looks like this;
and finally, the POST method;
[HttpPost]
public ActionResult Edit(EditViewModel model)
{
if (ModelState.IsValid)
{
var categories = _usersService.GetUser(User.Id).Categories;
var list = _listsService.GetList(model.Id);
list.Description = model.Description;
list.Category = categories.FirstOrDefault(x => x.Id == model.CategoryId);
_listsService.Update(list);
categories.Insert(0, new Category { Description = "", Id = 0 });
model.Categories = new SelectList(categories.AsEnumerable(), "Id", "Description");
return View(model);
}
return View(model);
}
So, in the following scenarios, this is what happens. For clarity, each time I am doing this, I go back to the Lists Index and GET Edit again;
Select '' from the Dropdown - NO Categories INSERT,UPDATE on Lists table only, setting [Category_Id] = NULL - Correct
SELECT 'Category 1' from DropDown. INSERT categories, UPDATE lists - NOT Correct
The code being used to update the List is;
public void Update(T entity)
{
if (entity == null) throw new ArgumentNullException(nameof(entity));
_context.Entry(entity).State = EntityState.Modified;
_context.SaveChanges();
}
Now, I know this is something I am doing, but being new to EF, I have no idea.
The problem was down to how the values were being set.
I needed to set the Foreign Key and assign the value to this.
public class List : Entity<int>
{
public int CategoryId { get; set; }
[ForeignKey("CategoryId")
public Category Category { get; set; }
}
and the value was then set as
var list = _listsService.GetList(model.Id);
list.Description = model.Description;
list.CategoryId = model.CategoryId;
list.Category = null;
_listsService.Update(list);
After this, when getting the list from the repository, both the Category and CategoryID would be populated correctly.
The issue was down the setting the Entity as modified, this internally indicated that the Category was 'new' when in fact it was not. You could also 'attach' and existing category to the entity/context but decided the method above was better.
A slightly better approach to the above would be to create a new 'UpdateList' method which could be called rather than the generic update. This method would perform the setting of the relevant properties outside of the controller method.
I am not sure but possible you must write your update method as follow:
public void Update(T entity)
{
if (entity == null) throw new ArgumentNullException(nameof(entity));
var item = _collection.Find(item.Id);
if (item == null) throw new ArgumentNullException(nameof(item ));
_context.Entry(item).CurrentValues.SetValues(entity);
_context.SaveChanges();
}
The problem can be in view, of you don't have the I'd the EF will add new record instead of update the existing record.
In general: Watch out for existing classes when you name your custom class (like List):
public class List : Entity<int>
{
public Category Category { get; set; }
}
Be shoure that you use the right class in the right namespace.
var user = new User
{
Email = "",
Categories = new YourOwnNamespace.List<Category>
{
new Category
{
Description = "Category 1",
},
new Category
{
Description = "Category 2",
}
}
};
Avoid naming classes and properties to existing names. Beter change List class in e.g. 'MyList'.
Need a help with RavenDB.
In my web page I want to have such list:
item1 category1
item2 category2
...
and another one:
category1, number of items
category2, number of items
...
My data structures:
public class Item
{
public string Id { get; set; }
public string Name { get; set; }
public string CategoryId { get; set; }
}
public class Category
{
public string Id { get; set; }
public string Name { get; set; }
public bool IsActive { get; set; }
}
Index for the first list:
public class Item_WithCategory : AbstractIndexCreationTask<Item>
{
public class Result
{
public string Name { get; set; }
public string CategoryName { get; set; }
}
public Item_WithCategory()
{
Map = items => from item in items
select new
{
Name = item.Name,
CategoryName = LoadDocument<Category>(item.CategoryId).Name
};
}
}
Is this data structure suitable for my case, or will it be better to have Category instead of CategoryId in item structure?
Should I use my index or is there a better solution to take category name?
If my index is good, how to write a correct query? My current try:
Item_WithCategory.Result[] all;
using (var session = DocumentStoreHolder.Store.OpenSession())
{
all = session.Query<Item_WithCategory.Result, Item_WithCategory>().ToArray();
}
but it throws exception stating that return type is item, not result. How to fix it?
You have a couple of options here. You could store both the CategoryId and the CategoryName on the Item entity. This will of course lead to duplicated data (if you still need to store the Category entity), but "storage is cheap" is a popular term these days.The downside of this is that you need to update each Item document of a given category if the category name changes to keep things consistent. A benefit is that you need to do less work to get your desired result.
If you store Category Name on the item as well you don't need a special index to handle the first list, just query on the Items and return what you need. For the second list you need to create a Map/Reduce index on the Item entity that groups on the category.
However, if you need to use the data structure you've given, there are a couple of ways of solving this. First, it's really not recommended to use a LoadDocument inside of an index definition, especially not in a select statement. This might affect indexing performance in a negative way.
Instead, just index the properties you need to query on (or use an auto index) and then use a Result Transformer to fetch information from related documents:
public class ItemCategoryTransformer : AbstractTransformerCreationTask<Item>
{
public ItemCategoryTransformer()
{
TransformResults = results => from item in results
let category = LoadDocument<Category>(item.CategoryId)
select new ItemCategoryViewModel
{
Name = item.Name,
CategoryName = category.Name
};
}
}
public class ItemCategoryViewModel
{
public string Name { get; set; }
public string CategoryName { get; set; }
}
You can use this Transformer with a Query on the Item entity:
using (var session = documentStore.OpenSession())
{
var items = session.Query<Item>()
.TransformWith<ItemCategoryTransformer, ItemCategoryViewModel>()
.ToList();
}
As for the second list, still using your data structure, you have to use a couple of things. First, a Map/Reduce index over the Items, grouped by CategoryId:
public class Category_Items_Count : AbstractIndexCreationTask<Item, Category_Items_Count.Result>
{
public class Result
{
public string CategoryId { get; set; }
public int Count { get; set; }
}
public Category_Items_Count()
{
Map = items => from item in items
select new Result
{
CategoryId = item.CategoryId,
Count = 1
};
Reduce = results => from result in results
group result by result.CategoryId
into c
select new Result
{
CategoryId = c.Key,
Count = c.Sum(x => x.Count)
};
}
}
But as you only have the CategoryId on the Item entity, you have to use a similar transformer as in the first list:
public class CategoryItemsCountTransformer : AbstractTransformerCreationTask<Category_Items_Count.Result>
{
public CategoryItemsCountTransformer()
{
TransformResults = results => from result in results
let category = LoadDocument<Category>(result.CategoryId)
select new CategoryItemsCountViewModel
{
CategoryName = category.Name,
NumberOfItems = result.Count
};
}
}
public class CategoryItemsCountViewModel
{
public string CategoryName { get; set; }
public int NumberOfItems { get; set; }
}
And lastly, query for it like this:
using (var session = documentStore.OpenSession())
{
var items = session.Query<Category_Items_Count.Result, Category_Items_Count>()
.TransformWith<CategoryItemsCountTransformer, CategoryItemsCountViewModel>()
.ToList();
}
As you can see, there are quite a difference in work needed depending on what data structure you're using. If you stored the Category Name on the Item entity directly you wouldn't need any Result Transformers to achieve the results you're after (you would only need a Map/Reduce index).
However, Result Transformers are executed server side and are only executed on request, instead of using LoadDocument inside of an index which is executed every time indexing occurs. Also, and maybe why LoadDocuments inside of index definitions isn't recommended, every change to a document that's referenced with a LoadDocument in an index will cause that index to have to be rewritten. This might lead to a lot of work for the index engine.
Lastly, to answer your last question about why you get an exception when querying: As the actual return type of your index is the document that that's being indexed (in this case Item). To use something else you need to project your result to something else. This can be done by using ".As()" in the query:
Item_WithCategory.Result[] all;
using (var session = DocumentStoreHolder.Store.OpenSession())
{
all = session.Query<Item_WithCategory.Result, Item_WithCategory>()
.As<Item_WithCategory.Result>()
.ToArray();
}
Long post, but hope it helps!
I have the following entity collections in RavenDB:
public class EntityA
{
public string Id { get; set; }
public string Name { get; set; }
public string[] Tags { get; set; }
}
public class EntityB
{
public string Id { get; set; }
public string Name { get; set; }
public string[] Tags { get; set; }
}
The only thing shared is the Tags collection: a tag of EntityA may exist in EntityB, so that they may intersect.
How can I retrieve every EntityA that has intersecting tags with EntityB where the Name property of EntityB is equal to a given value?
Well, this is a difficult one. To do it right, you would need two levels of reducing - one by the tag which would expand out your results, and another by the id to collapse it back. Raven doesn't have an easy way to do this.
You can fake it out though using a Transform. The only problem is that you will have skipped items in your result set, so make sure you know how to deal with those.
public class TestIndex : AbstractMultiMapIndexCreationTask<TestIndex.Result>
{
public class Result
{
public string[] Ids { get; set; }
public string Name { get; set; }
public string Tag { get; set; }
}
public TestIndex()
{
AddMap<EntityA>(entities => from a in entities
from tag in a.Tags.DefaultIfEmpty("_")
select new
{
Ids = new[] { a.Id },
Name = (string) null,
Tag = tag
});
AddMap<EntityB>(entities => from b in entities
from tag in b.Tags
select new
{
Ids = new string[0],
b.Name,
Tag = tag
});
Reduce = results => from result in results
group result by result.Tag
into g
select new
{
Ids = g.SelectMany(x => x.Ids),
g.First(x => x.Name != null).Name,
Tag = g.Key
};
TransformResults = (database, results) =>
results.SelectMany(x => x.Ids)
.Distinct()
.Select(x => database.Load<EntityA>(x));
}
}
See also the full unit test here.
There is another approach, but I haven't tested it yet. That would be to use the Indexed Properties Bundle to do the first pass, and then map those results for the second pass. I am experimenting with this in general, and if it works, I will update this answer with the results.