I have the code below which works:
List<XXTJobTableModel> xjobs = filexxts.GroupBy(x=> x.job)
.Select(fx => new JobTableModel
{
job_no = fx.First().job,
emps = fx.GroupBy(x=>x.emp_id).Select(x => new EmployeeTableModel
{
eid = x.First().emp_id,
heds = x.GroupBy(h => h.HED).Select(h => new HEDModel
{
hed = h.First().HED,
hours = h.Sum(c => c.HOURS),
amt = h.Sum(c => c.AMOUNTRATE)
}).ToList()
}).ToList()
}).ToList();
public class JobTableModel
{
public string job_no { get; set; }
public List<EmployeeTableModel> emps { get; set; }
}
public class EmployeeTableModel
{
public string emp_id { get; set; }
public List<HEDModel> heds { get; set; }
}
public class THEDModel
{
public string hed { get; set; }
public decimal hours { get; set; }
public decimal amt { get; set; }
}
I have another List<XXTJobTableModel> yjobs already loaded from another data source. What I would like to do, if the job_no is not found in yjobs, then add the job (with employee and he data) to yjobs. If the job_no is found in yjobs, and the emp_id is not found in the Employee table for that job, then add the employee (and hed data) to that jobs. If the employee is found in that job, then just add the HED data to the employees list.
I do not have a preference if I somehow merge xjobs and yjobs or if I load the xjobs directly into the yjobs list.
thanks
Are you looking for a very concise set of LINQ statements to do this merge operation or just any solution at all? What I would do is loop through one set and use LINQ to compare each item to the other set, and add items resulting from the comparison to a third set. Problems like this you have to decompose into manageable pieces, and then recompose it into a larger solution once the smaller pieces are working. Make an attempt and if you get stuck someone on here will surely be able to fill in the blanks.
Related
While using LinQ, retrieving data from foreign key table data are available. But when I try to 'Add' into my ViewModel this warnings shows. Warningsare difference from each other. such as,
Cannot implicitly convert type 'System.Collection.Generic.IEnumerable<string>' to 'string'
and
Cannot implicitly convert type 'System.Collection.Generic.IEnumerable<System.Collection.Generic.IEnumerable.IEnumerable<string>' to 'string'.
I tried casting to ToString() but it was worthless, no errors shows but data was replaced with system messages. I also tried to LinQ Join in students but I was unable to show Skills Comma Separated that way.
Here is my code:
public ActionResult GetStudentsInfo ()
{
var students = (from stud in db.Students
group stud by stud.StudentId into sg
select new
{
studentName=sg.Select(s=>s.StudentName).FirstOrDefault(),
coutryName=sg.Select(c=>c.Country.CountryName),
cityName=sg.Select(ct=>ct.Country.Cities.Select(x=>x.CityName)),
skillName=sg.Select(sk=>sk.StudentSkills.Select(s=>s.Skill.SkillName)),
resumeName=sg.Select(r=>r.Resumes.Select(m=>m.ResumeName)),
dob=sg.Select(d=>d.DateOfBirth)
}).ToList();
List<StudentListVM> studentLists=new List<StudentListVM>();
foreach (var item in students)
{
studentLists.Add(new StudentListVM
{
studentName = item.studentName,
country = item.coutryName, //warnings here
city = item.cityName, //warnings here
skills = string.Join(",", item.skillName),
resume = item.resumeName, //warnings here
dateOfBirth = item.dob //warnings here
});
}
return View(studentLists);
}
```
StudentListVM class
public class StudentListVM
{
public string studentName { get; set; }
public string country { get; set; }
public string city { get; set; }
public string skills { get; set; }
public string resume { get; set; }
public DateTime dateOfBirth { get; set; }
}
```
I tried this before
var students = (from stud in db.Students
join con in db.Countries on stud.CountryId equals con.CountryId
join ct in db.Cities on stud.CityId equals ct.CityId
join rsm in db.Resumes on stud.ResumeID equals rsm.ResumeId
join stsk in db.StudentSkills on stud.StudentId equals stsk.StudentId
//group stud by stud.StudentId into sg
select new StudentListVM()
{
studentName = stud.StudentName,
countries = con.CountryName,
cities = ct.CityName,
skills=stsk.Skill.SkillName,
resumes = rsm.ResumeName,
dateOfBirth = stud.DateOfBirth,
}).ToList();
```
StudentSkill class:
public partial class StudentSkill
{
public int StudentSkillsId { get; set; }
public int StudentId { get; set; }
public int SkillId { get; set; }
public virtual Student Student { get; set; }
public virtual Skill Skill { get; set; }
}
```
This returns All fine except The Skills in a comma separated list. All I need to show my multiple skills that are checked multiply and added to the database in a separated table name StudentSkills. Is there any good solution to do it?
You are trying to assign a group of strings, specifically the various IEnumerable<string> collections, into a single string due to your Select() calls.
For example, this line is clearly selecting more than one resume name.
resumeName=sg.Select(r=>r.Resumes.Select(m=>m.ResumeName))
If you don't care and expect them to be all the same value you could just grab the first one:
resume = item.resumeName.FirstOrDefault()
Or flatten the collection some other way.
That said, there's something off with the design when you grab a collection and try to assign it to a single item.
Try to change this line:
skills = string.Join(",", item.skillName),
With this:
skills = string.Join(",", item.skillName.ToArray()),
The problem you have is not in your code. The problem is how you think you are solving it. Think it right, the solution will be right. #Zer0 already mentioned that but you probably need more explanation. I will try to explain with some assumption that you might be wanting to do --
1: If Student can have multiple country, city, skill and resumes, then the StudentVM class you have is most certainly wrong. By definition it only supports one city, country, skill, etc. Modify it to support multiples -
public class StudentListVM
{
public string studentName { get; set; }
public List<string> countries { get; set; }
public List<string> cities { get; set; }
public string skills { get; set; }
public List<string> resume { get; set; }
//does not make sense to have a list, a person has only one DOB
public DateTime dateOfBirth { get; set; }
}
then the code you have will work -
public ActionResult GetStudentsInfo ()
{
var students = (from stud in db.Students
group stud by stud.StudentId into sg
select new
{
studentName=sg.Select(s=>s.StudentName).FirstOrDefault(),
coutryName=sg.Select(c=>c.Country.CountryName),
cityName=sg.Select(ct=>ct.Country.Cities.Select(x=>x.CityName)),
skillName=sg.Select(sk=>sk.StudentSkills.Select(s=>s.Skill.SkillName)),
resumeName=sg.Select(r=>r.Resumes.Select(m=>m.ResumeName)),
dob=sg.Select(d=>d.DateOfBirth).FirstOrDefault()
}).ToList();
List<StudentListVM> studentLists=new List<StudentListVM>();
foreach (var item in students)
{
studentLists.Add(new StudentListVM
{
studentName = item.studentName,
countries = item.coutryName.ToList(), //should work, as these are lists
cities = item.cityName.ToList(), //should work, as these are lists
skills = string.Join(",", item.skillName),
resume = item.resumeName.ToList(), //should work, as these are lists
dateOfBirth = item.dob //does not make sense to have a list, a person has only one DOB
});
}
return View(studentLists);
}
2: Once the class is okay, you could shorten the code. You don't need a second block to create a typed list, you can do it directly -
public ActionResult GetStudentsInfo ()
{
var students = (from stud in db.Students
group stud by stud.StudentId into sg
select new StudentListVM
{
studentName=sg.Select(s=>s.StudentName).FirstOrDefault(),
countries=sg.Select(c=>c.Country.CountryName).ToList(),
cities=sg.SelectMany(ct=>ct.Country.Cities.Select(x=>x.CityName)).ToList(),
skills=string.Join(",", sg.Select(sk=>sk.StudentSkills.Select(s=>s.Skill.SkillName))),
resume=sg.SelectMany(r=>r.Resumes.Select(m=>m.ResumeName)).ToList(),
//does not make sense to have a list, a person has only one DOB
dob=sg.Select(d=>d.DateOfBirth).FirstOrDefault()
}).ToList();
return View(students);
}
3: If the above does not make sense, then the idea is not right. Think of what you are trying to achieve and update the question. May be then people will be able to help.
You have said -
Actually I can do them separately in different ways but I can't do it in a single code
So what are those ways? Mentioning them will probably give an idea of what you are trying to achieve. The details on the question is not enough to give you solution. It does not say what you are trying to do.
I have referenced numerous questions on this site related to calculated fields and ViewModels, but I can't seem to extrapolate from examples given. I hope that laying out a specific scenario would allow someone to pin point what I can't see. I am new to WebApp design in general. Please take that into consideration. Also, if I've left off any relevant information, please let me know and I will update the question.
Here is the scenario:
I have a complex query that is spanning multiple tables to return data used in calculations. Specifically, I store units for a recipe converted to a base unit and then convert the quantity to the units specified by the user.
I am using AutoMapper to map from entities to ViewModels and vice versa, but I am not sure how to handle the calculated values. Especially with the nested ViewModel Collection thrown into the mix.
Option 1
Do I return an autonomous set of data? Like the following... and then somehow use AutoMapper to do the mapping? Perhaps I would need to do the mapping manually, which I haven't found a solid example which includes nested ViewModels. At this point, I'm not even sure if the following code handles the nested collection correctly for the autonomous data.
var userId = User.Identity.GetUserId();
var recipes = from u in db.Users.Where(u => u.Id == userId)
from c in db.Categories
from r in db.Recipes
join ur in db.UserRecipes.Where(u => u.UserId == userId) on r.Id equals ur.RecipeId
join mus in db.MeasUnitSystems on ur.RecipeYieldUnitSysId equals mus.Id
join muc in db.MeasUnitConvs on mus.Id equals muc.UnitSysId
join mu in db.MeasUnits on mus.UnitId equals mu.Id
join msy in db.MeasUnitSymbols on mu.Id equals msy.UnitId
select new
{
Id = c.Id,
ParentId = c.ParentId,
Name = c.Name,
Descr = c.Descr,
Category1 = c.Category1,
Category2 = c.Category2,
Recipes = new
{
Id = r.Id,
Title = r.Title,
Descr = r.Descr,
Yield = String.Format("{0} {1}", ((r.Yield * muc.UnitBaseConvDiv / muc.UnitBaseConvMult) - muc.UnitBaseConvOffset), msy.Symbol)
}
};
Option 2
Another option that crossed my mind was to return the entities and use AutoMapper as I normally would. Then iterate through the collections and perform the calculations there. I feel like I could make this work, but it seems inefficient to me because it would result in many queries back to the database.
Option 3
???? I can't think of any other method to do this. But, please, if you have suggestions, I am more than willing to hear them.
Relevant Data
Here is the query returning the data I want in SQL Server (more or less).
declare #uid as nvarchar(128) = 'da5435ae-5198-4690-b502-ea3723a9b217'
SELECT c.[Name] as [Category]
,r.Title
,r.Descr
,(r.Yield*rmuc.UnitBaseConvDiv/rmuc.UnitBaseConvMult)-rmuc.UnitBaseConvOffset as [Yield]
,rmsy.Symbol
FROM Category as c
inner join RecipeCat as rc on c.Id = rc.CategoryId
inner join Recipe as r on rc.RecipeId = r.Id
inner join UserRecipe as ur on r.Id = ur.RecipeId and ur.UserId = #uid
inner join MeasUnitSystem as rmus on ur.RecipeYieldUnitSysId = rmus.Id
inner join MeasUnitConv as rmuc on rmus.Id = rmuc.UnitSysId
inner join MeasUnit as rmu on rmus.UnitId = rmu.Id
inner join MeasUnitSymbol as rmsy on rmu.Id = rmsy.UnitId
inner join UserUnitSymbol as ruus on rmsy.UnitId = ruus.UnitId and rmsy.SymIndex = ruus.UnitSymIndex and ruus.UserId = #uid
ViewModels
public class CategoryRecipeIndexViewModel
{
public int Id { get; set; }
public int ParentId { get; set; }
[Display(Name = "Category")]
public string Name { get; set; }
[Display(Name = "Description")]
public string Descr { get; set; }
public ICollection<CategoryRecipeIndexViewModel> Category1 { get; set; }
public CategoryRecipeIndexViewModel Category2 { get; set; }
public ICollection<RecipeIndexViewModel> Recipes { get; set; }
}
public class RecipeIndexViewModel
{
public int Id { get; set; }
[Display(Name = "Recipe")]
public string Title { get; set; }
[Display(Name = "Description")]
public string Descr { get; set; }
[Display(Name = "YieldUnit")]
public string Yield { get; set; }
}
UPDATE 2/10/2018
I found an answer here that does a very good job of explaining exactly what I'm looking at. Particularly under the A Better solution ? section. Mapping queries directly to my ViewModels looks like it would allow me to get my calculated values as well. Problem is, the example given is once again too simplistic.
He gives the following DTO's
public class UserDto
{
public int Id {get;set;}
public string Name {get;set;}
public UserTypeDto UserType { set; get; }
}
public class UserTypeDto
{
public int Id { set; get; }
public string Name { set; get; }
}
And does the following for mapping:
var users = dbContext.Users.Select(s => new UserDto
{
Id = s.Id,
Name = s.Name,
UserType = new UserTypeDto
{
Id = s.UserType.Id,
Name = s.UserType.Name
}
});
Now what if the UserDTO looked like this:
public class UserDto
{
public int Id {get;set;}
public string Name {get;set;}
public ICollection<UserTypeDto> UserTypes { set; get; }
}
How would the mapping be done if the UserTypes were a collection?
Update 2/13/2018
I feel I am making progress, but am currently headed in the wrong direction. I found this and came up with the following (which currently errors because of the method call in the linq query):
*Note: I removed Category2 from the ViewModel as I found it was not needed and only complicated this further.
query inside index controller method
IEnumerable<CategoryRecipeIndexViewModel> recipesVM = db.Categories
.Where(x => x.ParentId == null)
.Select(x => new CategoryRecipeIndexViewModel()
{
Id = x.Id,
ParentId = x.ParentId,
Name = x.Name,
Descr = x.Descr,
Category1 = MapCategoryRecipeIndexViewModelChildren(x.Category1),
Recipes = x.Recipes.Select(y => new RecipeIndexViewModel()
{
Id = y.Id,
Title = y.Title,
Descr = y.Descr
})
});
Recursive Method
private static IEnumerable<CategoryRecipeIndexViewModel> MapCategoryRecipeIndexViewModelChildren(ICollection<Category> categories)
{
return categories
.Select(c => new CategoryRecipeIndexViewModel
{
Id = c.Id,
ParentId = c.ParentId,
Name = c.Name,
Descr = c.Descr,
Category1 = MapCategoryRecipeIndexViewModelChildren(c.Category1),
Recipes = c.Recipes.Select(r => new RecipeIndexViewModel()
{
Id = r.Id,
Title = r.Title,
Descr = r.Descr
})
});
}
At this point, I don't even have the calculations I require, but that doesn't matter until I get this working (small steps). I quickly discovered you can't really call a method inside a Linq Query. Then a thought occurs to me, if I need to force the Linq Query to execute and then perform all the mapping on the in memory data, then I would essentially be doing the same thing as Option 2 (above), but I could perform the calculations within the ViewModel. This is the solution I will pursue and will keep everyone posted.
You have to iterate over UserType Collection and map the value to UserType dto's collection.
Use this code.
var users = dbContext.Users.Select(s => new UserDto
Id = s.Id,
Name = s.FullName,
UserType = s.UserType.Select(t => new UserTypeDto
{
Id = t.Id,
Name = t.Name
}).ToList()
Hope this will help.
I got it working! ...I think. ...Maybe. If anything, I'm querying the data, mapping it to my ViewModels and I have the calculations too. I do have additional questions, but they are a lot more specific. I will layout the solution I followed and where I think it requires work below.
I basically implemented my Option 2 from above, but instead of iterating through the collections, I just performed the calculations within the ViewModels.
Controller Method
public ActionResult Index()
{
var userId = User.Identity.GetUserId();
var recipes = db.Categories.Where(u => u.Users.Any(x => x.Id == userId))
.Include(c => c.Category1)
.Include(r => r.Recipes
.Select(u => u.UserRecipes
.Select(s => s.MeasUnitSystem.MeasUnitConv)))
.Include(r => r.Recipes
.Select(u => u.UserRecipes
.Select(s => s.MeasUnitSystem.MeasUnit.MeasUnitSymbols)));
IEnumerable<CategoryRecipeIndexViewModel> recipesVM = Mapper.Map<IEnumerable<Category>, IEnumerable<CategoryRecipeIndexViewModel>>(recipes.ToList());
return View(recipesVM);
}
View Models
public class CategoryRecipeIndexViewModel
{
public int Id { get; set; }
public int ParentId { get; set; }
[Display(Name = "Category")]
public string Name { get; set; }
[Display(Name = "Description")]
public string Descr { get; set; }
public ICollection<CategoryRecipeIndexViewModel> Category1 { get; set; }
public ICollection<RecipeIndexViewModel> Recipes { get; set; }
}
public class RecipeIndexViewModel
{
public int Id { get; set; }
[Display(Name = "Recipe")]
public string Title { get; set; }
[Display(Name = "Description")]
public string Descr { get; set; }
public double Yield { get; set; }
public ICollection<UserRecipeIndexViewModel> UserRecipes { get; set; }
[Display(Name = "Yield")]
public string UserYieldUnit
{
get
{
return System.String.Format("{0} {1}", ((Yield *
UserRecipes.FirstOrDefault().MeasUnitSystem.MeasUnitConv.UnitBaseConvDiv /
UserRecipes.FirstOrDefault().MeasUnitSystem.MeasUnitConv.UnitBaseConvMult) -
UserRecipes.FirstOrDefault().MeasUnitSystem.MeasUnitConv.UnitBaseConvOffset).ToString("n1"),
UserRecipes.FirstOrDefault().MeasUnitSystem.MeasUnit.MeasUnitSymbols.FirstOrDefault().Symbol);
}
}
}
public class UserRecipeIndexViewModel
{
public MeasUnitSystemIndexViewModel MeasUnitSystem { get; set; }
}
public class MeasUnitSystemIndexViewModel
{
public MeasUnitIndexViewModel MeasUnit { get; set; }
public MeasUnitConvIndexViewModel MeasUnitConv { get; set; }
}
public class MeasUnitIndexViewModel
{
public ICollection<MeasUnitSymbolIndexViewModel> MeasUnitSymbols { get; set; }
}
public class MeasUnitConvIndexViewModel
{
public double UnitBaseConvMult { get; set; }
public double UnitBaseConvDiv { get; set; }
public double UnitBaseConvOffset { get; set; }
}
public class MeasUnitSymbolIndexViewModel
{
public string Symbol { get; set; }
}
This appears to be working, but I know it needs some work.
For instance, the relation shown between the Recipe and UserRecipe shows one to many. In reality, if the UserRecipe were filtered by the current user, the relationship would be one to one. Also, the same goes for the MeasUnit and the MeasUnitSymbol entities. Currently, I'm relying on the FirstOrDefault of those collections to actually perform the calculations.
Also, I have seen numerous posts that state that calculations should not be done in the View Models. Except for some who say it's okay if it is only a requirement of the View.
Last I will say that paying attention to variable names within the ViewModels would have saved me some headaches. And I thought I knew how to utilize Linq Queries, but had issues with the data returned. It was easier to rely on the eager loading provided by Entity Framework to bring back the hierarchical data structure needed, versus the flat table structures I'm used to working with.
I'm still new to a lot of this and wrapping my head around some of the quirks of MVC and Entity Framework leaves me brain dead after a few hours, but I will continue to optimize and adopt better programming methods as I go.
Ok, I'll try and make this make sense.
In a model, Lead, among other properties, we have these:
public class Lead
{
....
public int LeadID {get; set; }
public virtual ICollection<QuoteRevision> QuoteRevisions { get; set; }
....
}
And QuoteRevision...
public class QuoteRevision
{
....
[ForeignKey(nameof(LeadID))]
public virtual Lead Lead { get; set; }
public virtual ICollection<QuoteRevisionProduct> QuoteRevisionProduct{ get; set; }
....
}
And the model for QuoteRevisionProduct:
public class QuoteRevisionProduct
{
....
[ForeignKey(nameof(QuoteRevisionID))]
public virtual QuoteRevision QuoteRevision { get; set; }
[ForeignKey("ProductID")]
public virtual Product Product { get; set; }
....
}
And last of all...
public class Product
{
....
public string Code { get; set; }
....
}
Ok. So these are the models I need to query to build an object called QuoteSearchItem that has multiple properties. Here's two of them:
public class QuoteSearchItem
{
....
public LeadID {get; set; }
public List<string> Codes { get; set; }
....
}
I'm starting with this IQueryable of all rows in Lead:
leads = IQueryable<Lead>
And then doing this:
var results = from l in leads
from qr in l.QuoteRevisions
from rp in qr.RevisionProducts
select new QuoteSearchItem
{
....
LeadID = l.LeadID,
AdditionalProducts = ???
....
};
I'm not sure how to get that list of Codes. I can do this:
Code = rp.Product.Code,
And that will get me a single code, the first in the list. But how do I get ALL that match?
I know this was a lot to follow. I hope it makes sense. Thank you!
EDIT:
This is (almost) the SQL that I'm looking for:
SELECT
l.ID,
p.Code
FROM
dbo.Leads AS l
JOIN QuoteRevisions qr ON qr.LeadID = l.ID
JOIN QuoteRevisionProducts qrp on qrp.QuoteRevisionID = qr.QuoteRevisionID
JOIN Products p on p.ProductID = qrp.ProductID
Except that this will just return multiple rows per product. But, at least it gives an idea.
EDIT 2:
Code = l.QuoteRevisions.SelectMany(qr => qr.RevisionProducts).Select(p => p.Product.Code).ToList()
This doesn't throw an error, but it's returning a row of data for each code, which isn't what I need.
You can use SelectMany to flatten the models and get all the codes, something like this:
var results = from l in leads
select new QuoteSearchItem
{
....
LeadID = l.LeadID,
Codes = l.QuoteRevisions.SelectMany(qr => qr.QuoteRevisionProduct)
.Select(p => p.Product.Code)
....
};
not sure how your DB looks, but you can probably use Distinct as well to eliminate duplicate Codes
I really love Dapper's simplicity and possibilities. I would like to use Dapper to solve common challenges I face on a day-to-day basis. These are described below.
Here is my simple model.
public class OrderItem {
public long Id { get; set; }
public Item Item { get; set; }
public Vendor Vendor { get; set; }
public Money PurchasePrice { get; set; }
public Money SellingPrice { get; set; }
}
public class Item
{
public long Id { get; set; }
public string Title { get; set; }
public Category Category { get; set; }
}
public class Category
{
public long Id { get; set; }
public string Title { get; set; }
public long? CategoryId { get; set; }
}
public class Vendor
{
public long Id { get; set; }
public string Title { get; set; }
public Money Balance { get; set; }
public string SyncValue { get; set; }
}
public struct Money
{
public string Currency { get; set; }
public double Amount { get; set; }
}
Two challenges have been stumping me.
Question 1:
Should I always create a DTO with mapping logic between DTO-Entity in cases when I have a single property difference or simple enum/struct mapping?
For example: There is my Vendor entity, that has Balance property as a struct (otherwise it could be Enum). I haven't found anything better than that solution:
public async Task<Vendor> Load(long id) {
const string query = #"
select * from [dbo].[Vendor] where [Id] = #id
";
var row = (await this._db.QueryAsync<LoadVendorRow>(query, new {id})).FirstOrDefault();
if (row == null) {
return null;
}
return row.Map();
}
In this method I have 2 overhead code:
1. I have to create LoadVendorRow as DTO object;
2. I have to write my own mapping between LoadVendorRow and Vendor:
public static class VendorMapper {
public static Vendor Map(this LoadVendorRow row) {
return new Vendor {
Id = row.Id,
Title = row.Title,
Balance = new Money() {Amount = row.Balance, Currency = "RUR"},
SyncValue = row.SyncValue
};
}
}
Perhaps you might suggest that I have to store amount & currency together and retrieve it like _db.QueryAsync<Vendor, Money, Vendor>(...)- Perhaps, you are right. In that case, what should I do if I need to store/retrive Enum (OrderStatus property)?
var order = new Order
{
Id = row.Id,
ExternalOrderId = row.ExternalOrderId,
CustomerFullName = row.CustomerFullName,
CustomerAddress = row.CustomerAddress,
CustomerPhone = row.CustomerPhone,
Note = row.Note,
CreatedAtUtc = row.CreatedAtUtc,
DeliveryPrice = row.DeliveryPrice.ToMoney(),
OrderStatus = EnumExtensions.ParseEnum<OrderStatus>(row.OrderStatus)
};
Could I make this work without my own implementations and save time?
Question 2:
What should I do if I'd like to restore data to entities which are slightly more complex than simple single level DTO? OrderItem is beautiful example. This is the technique I am using to retrieve it right now:
public async Task<IList<OrderItem>> Load(long orderId) {
const string query = #"
select [oi].*,
[i].*,
[v].*,
[c].*
from [dbo].[OrderItem] [oi]
join [dbo].[Item] [i]
on [oi].[ItemId] = [i].[Id]
join [dbo].[Category] [c]
on [i].[CategoryId] = [c].[Id]
join [dbo].[Vendor] [v]
on [oi].[VendorId] = [v].[Id]
where [oi].[OrderId] = #orderId
";
var rows = (await this._db.QueryAsync<LoadOrderItemRow, LoadItemRow, LoadVendorRow, LoadCategoryRow, OrderItem>(query, this.Map, new { orderId }));
return rows.ToList();
}
As you can see, my question 1 problem forces me write custom mappers and DTO for every entity in the hierarchy. That's my mapper:
private OrderItem Map(LoadOrderItemRow row, LoadItemRow item, LoadVendorRow vendor, LoadCategoryRow category) {
return new OrderItem {
Id = row.Id,
Item = item.Map(category),
Vendor = vendor.Map(),
PurchasePrice = row.PurchasePrice.ToMoney(),
SellingPrice = row.SellingPrice.ToMoney()
};
}
There are lots of mappers that I'd like to eliminate to prevent unnecessary work.
Is there a clean way to retrive & map Order
entity with relative properties like Vendor, Item, Category etc)
You are not showing your Order entity but I'll take your OrderItem as an example and show you that you don't need a mapping tool for the specific problem (as quoted). You can retrieve the OrderItems along with the Item and Vendor info of each by doing the following:
var sql = #"
select oi.*, i.*, v.*
from OrderItem
inner join Item i on i.Id = oi.ItemId
left join Vendor v on v.Id = oi.VendorId
left join Category c on c.Id = i.CategoryId";
var items = connection.Query<OrderItem, Item, Vendor, Category, OrderItem>(sql,
(oi,i,v,c)=>
{
oi.Item=i;oi.Item.Category=c;oi.Vendor=v;
oi.Vendor.Balance = new Money { Amount = v.Amount, Currency = v.Currency};
return oi;
});
NOTE: The use of left join and adjust it accordingly based on your table structure.
I'm not sure I understand your question a 100%. And the fact that no one has attempted to answer it yet, leads me to believe that I'm not alone when I say it might be a little confusing.
You mention that you love Dapper's functionality, but I don't see you using it in your examples. Is it that you want to develop an alternative to Dapper? Or that you don't know how to use Dapper in your code?
In any case, here's a link to Dapper's code base for your review:
https://github.com/StackExchange/dapper-dot-net
Hoping that you'd be able to clarify your questions, I'm looking forward to your reply.
At the moment, I have multiple tables in my Database with slightly varying columns to define different "history" elements for an item.
So I have my item table;
int ItemId {get;set}
string Name {get;set}
Location Loc {get;set}
int Quantity {get;set}
I can do a few things to these items like Move, Increase Quantity, Decrease Quantity, Book to a Customer, "Pick" an item, things like that. So I have made multiple "History Tables" as they have different values to save E.g
public class MoveHistory
{
public int MoveHistoryId { get; set; }
public DateTime Date { get; set; }
public Item Item { get; set; }
public virtual Location Location1Id { get; set; }
public virtual Location Location2Id { get; set; }
}
public class PickingHistory
{
public int PickingHistoryId { get; set; }
public DateTime Date { get; set; }
public Item Item { get; set; }
public int WorksOrderCode { get; set; }
}
This is fine apart from where I want to show a complete history for an item displayed in a list;
Item 123 was moved on 23/02/2013 from Location1 to Location2
Item 123 was picked on 24/02/2013 from work order 421
I am using Entity Framework, .NET 4.5, WPF, and querying using Linq but cannot figure a way of taking these lists of history elements, and ordering them out one by one based on their date.
I can think of messy ways, like one single history table with columns used if required. Or even create a third list containing the date and what list it came from, then cycle through that list picking the corresponding contents from the corresponding list. However, I feel there must be a better way!
Any help would be appreciated.
If you implement a GetDescription() method on your history items (even as an extension method), you can do this:
db.PickingHistory.Where(ph => ph.Item.ItemId == 123)
.Select(ph => new { Time = ph.Date, Description = ph.GetDescription() })
.Concat(db.MoveHistory.Where(mh => mh.ItemId == 123)
.Select(mh => new { Time = mh.Date, Description = mh.GetDescription() })
.OrderByDescending(e => e.Time).Select(e => e.Description);
The problem you are facing is that you're trying to use your database model as a display model and obviously are failing. You need to create a new class that represents your history grid and then populate it from your various queries. From your example output the display model may be:
public class HistoryRow{
public DateTime EventDate { get; set; }
public string ItemName { get; set; }
public string Action { get; set; }
public string Detail { get; set; }
}
You then load the data into this display model:
var historyRows = new List<HistoryRow>();
var pickingRows = _db.PickingHistory.Select(ph => new HistoryRow{
EventDate = ph.Date,
ItemName = ph.Item.Name,
Action = "picked",
Detail = "from works order " + ph.WorksOrderCode);
historyRows.AddRange(pickingRows);
var movingRows = _db.MoveHistory.Select(mh => new HistoryRow{
EventDate = mh.Date,
ItemName = ph.Item.Name,
Action = "moved",
Detail = "from location " + mh.Location1Id + " to location " + mh.Location2Id);
historyRows.AddRange(movingRows );
You can repeatedly add the rows from various tables to get a big list of the HistoryRow actions and then order that list and display the values as you wish.
foreach(var historyRow in historyRows)
{
var rowAsString = historyRow.ItemName + " was " + historyRow.Action.....;
Console.WriteLine(rowAsString);
}
If you are implementing this in order to provide some sort of undo/redo history, then I think that you're going about it in the wrong way. Normally, you would have one collection of ICommand objects with associated parameter values, eg. you store the operations that have occurred. You would then be able to filter this collection for each item individually.
If you're not trying to implement some sort of undo/redo history, then I have misunderstood your question and you can ignore this.