I'm using EF code first and I have two classes that inherited from a base class(TPT):
public class Party
{
public int PartyId {get; set;}
}
public Person:Party
{
string FirstName { get; set; }
string LastName { get; set; }
}
public Organization:Party
{
string Name { get; set; }
}
Now, I want to create a query to fetch all Persons that their LastNames are equal to "SomeName" and all Organizations that their Name begins with "A" in one transaction.
Something like this
IList<Party> GetParties(string name, string organizationName)
{
IList<Party> result = new List<Party>();
using(var context = new MyContext())
{
var persons = context.Parties.OfType<Person>().Where(t=>t.LastName = name) ;
var organizations = context.Parties.OfType<Organization>().Where(t=>t.Name.StartWith(organizationName));
//return merge of persons and organizations
}
}
Is there any way to do this?
You can do
context.Parties.OfType<Person>().Where(t=>t.LastName = name).OfType<Party>()
.Concat(context.Parties.OfType<Organization>()
.Where(t=>t.Name.StartWith(organizationName)))
You don't have to cast the second collection to Party because it is concatenated with an IQueryable<Party> which is covariant with IQueryable<Organization>.
I did some LINQPad fiddling and I believe that this is the result you want.
IList<Party> GetParties(string name, string organizationName)
{
IList<Party> result = new List<Party>();
using(var context = new MyContext())
{
var persons = context.Parties.OfType<Person>().Where(t=>t.LastName = name) ;
var organizations = context.Parties.OfType<Organization>().Where(t=>t.Name.StartWith(organizationName));
//return merge of persons and organizations
result = (IList<Party>)persons.Union((IEnumerable<Party>)organizations);
}
return result;
}
Related
Initially I was using automapper for this but its seems way harder for me to implement it.
Basically, I just want to return an empty list instead of null values. I can do this on projects level but not on teammates level. The API must not return a null because the UI that consumes it will have an error.
Sample of my implementation below:
Projects = !Util.IsNullOrEmpty(x.Projects) ? x.Projects : new List<ProjectsDto>(),
Ill highly appreciate if someone can guide me on how to manually map this with null/empty checking.
If you can also provide and example using automapper that too will be very helpful.
public class Employee
{
public int Id { get; set; }
public string Name { get; set; }
public List<ProjectsDto> Projects { get; set; }
}
public class ProjectsDto
{
public string Status { get; set; }
public List<TeammatesDto> Teammates { get; set; }
}
public class TeammatesDto
{
public string TeammateName { get; set; }
public string PreviousProject { get; set; }
}
//Get by Id
var employee = await _context.Employees
.Where(x => x.id.Equals(request.Id)
.FirstOrDefaultAsync(cancellationToken);
//Map employee
EmployeeDto ret = new EmployeeDto()
{
Id = employee.id,
Name = employee.Name,
Projects = null //TODO: map manually
}
//Get all employees
var employees = await _context.Employees.AsNoTracking()
.ToListAsync(cancellationToken);
//Map here
IList<EmployeeDto> list = new List<EmployeeDto>();
foreach (var x in employees)
{
EmployeeDto dto = new EmployeeDto()
{
Id = x.id,
Name = x.Name,
Projects = null //TODO: map manually
};
list.Add(dto);
}
return list;
Instead of materializing full entities, do the following:
var query = _context.Employees
.Select(e = new EmployeeDto
{
Id = e.id,
Name = e.Name,
Projects = e.Projects.Select(p => new ProjectDto
{
Status = p.Status,
Templates = p.Templates.Select(t => new TemplateDto
{
TeammateName = t.TeammateName,
PreviousProject = t.PreviousProject
}).ToList()
}).ToList()
}
);
var result = await query.ToListAsync();
I'm trying to build a sub-query by using expression-trees. In linq I would write something like:
var single = MyTable
.AsExpandable()
.Select(c => new
{
Childs = Enumerable.Select(
MyTable.VisibleChilds.Invoke(c, dbContext),
cc => Convert(cfg.ChildsConfig).Invoke(dbContext, cc))
});
where the Convert is building an expression like
p => new MyTableSelect {
Id = p.Id,
Name = p.Name
}
depending on the given values from the config (to only read needed data from database).
but I'm struggeling with the second parameter to be passed to the Select call as I need cc to be passed to the Convert-call.
I guess I need something like Expression.Lambda<Func<>> but I don't see it.
Expression.Lambda>(Expression.Invoke(Instance.Convert(cfg.ChildOrganizersFilterConfig), ContextParameter, theEntity));
I am not familiar with your use of Invoke but if you just want to run a 'Converter' in a fluent syntax for use in a Linq Expression I could show you an example of that. Say I have three POCO classes, one parent container, a child container, and a container I want to convert to.
public class POC
{
public int Id { get; set; }
public string Name { get; set; }
public POC(int id, string name)
{
Id = id;
Name = name;
}
}
public class ChildPOC
{
public int ParentId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public ChildPOC(int parentId, string firstName, string lastName)
{
ParentId = parentId;
FirstName = firstName;
LastName = lastName;
}
}
public class ChildPOCAlter
{
public int ParentId { get; set; }
public string Name { get; set; }
public ChildPOCAlter(string first, string last, int parentId)
{
ParentId = parentId;
Name = $"{first} {last}";
}
}
I could write a converter method to take ChildPOC to ChildPOCAlter like so:
public static Converter<ChildPOC, ChildPOCAlter> ChildPOCOAlter()
{
return new Converter<ChildPOC, ChildPOCAlter>((x) => { return new ChildPOCAlter(x.FirstName, x.LastName, x.ParentId); });
}
I could then populate some data:
var someParents = new List<POC> { new POC(1, "A"), new POC(2, "B") };
var somechildren = new List<ChildPOC> { new ChildPOC(1, "Brett", "x"), new ChildPOC(1, "Emily", "X"), new ChildPOC(2, "John", "Y") };
And then I may want to take these relationships and apply a converter directly on it:
var relationships = someParents.Select(x => new
{
Id = x.Id,
Name = x.Name,
Children = somechildren.Where(y => y.ParentId == x.Id).ToList().ConvertAll(ChildPOCOAlter())
});
I'm sure someone else has asked this but I searched on what I could think of to find the solution.
I've got the following data models to match tables in my SQL db:
public class ProfileDetailModel
{
public string id { get; set; }
public string name { get; set; }
public StyleList[] styleList { get; set; }
public FabricList[] fabricList { get; set; }
}
public class StyleList
{
public string id { get; set; }
public string name { get; set; }
}
public class FabricList
{
public string id { get; set; }
public string fabricName { get; set; }
}
This is the current query code:
var query = (from t in db.tblProfiles
select new ProfileDetailModel()
{
id = t.id,
name = t.name
});
var querylist = await query.ToListAsync();
(prototyped linq queries below for style and fabric)
var styleQuery = (from t in db.tblStyles
select new styleList()
{
id = t.id,
name = t.name
});
var fabricQuery = (from t in db.tblFabrics
select new fabricList()
{
id = t.id,
name = t.name
});
if (queryList.Count > 0)
{
var item = queryList[0];
item.styleList = styleQuery;
item.fabricList = fabricQuery;
}
I'll have one profileDetailModel with multiple items in styleList and in fabricList. EG.
ProfileDetailModel
Data: Pants
styleList: Bell Bottom, Straight Leg, Boot fit
fabricList: jean-blue, jean-black, plaid
All three above models are tables in my db. I could issue 3 separate queries to read the data then assemble after the fact. But is there a way I can do a linq query to include the two arrays in the main query in one shot?
Try this:
var newQuery = (from p in db.tblProfiles
select p)
.AsEnumerable()
.Select(x => new ProfileDetailModel()
{
id = x.id,
name = x.name,
styleList = styleQuery,
fabricList = fabricQuery
});
I have a database that has two tables as follows, Please ignore the data but the format looks as follows
Now I have a Model class that is constructed as follows
public class FamilyModel
{
public string Name { get; set; }
public List<FamilyModel> FamilyList { get; set; }
public FamilyModel()
{
FamilyList = new List<FamilyModel>();
}
}
Now all I want is to get data from the two tables and populate the list.
So I have a stored procedure that returns data as follows
So I have written some code to populate the above class. But it dosent work. I get a count of 5 when I debug. I want the count to be 2 and when expanded I want something like FamilyA ->{Nick, Tom, Pam}.. FamilyB->{Harry} and so on. Please help fixing this code.
public static FamilyModel familyData()
{
//FamilyModel fml = new FamilyModel();
//fml.FamilyList = new List<FamilyModel>();
using (SqlConnection con = new SqlConnection(#"Data Source=(LocalDB)\v11.0; AttachDbFilename=|DataDirectory|\Families.mdf; Integrated Security=True; Connect Timeout=30;"))
{
con.Open();
SqlCommand cmd = new SqlCommand("sp_GetFamilies", con);
cmd.CommandType = CommandType.StoredProcedure;
SqlDataReader dr = cmd.ExecuteReader();
while (dr.Read()) {
FamilyModel fm = new FamilyModel();
fm.Name = dr["FamilyName"].ToString();
foreach (var item in dr["ChildName"].ToString())
{
if (Convert.ToInt32(dr["id"]) == Convert.ToInt32(dr["FID"]))
{
fm.FamilyList.Add(new FamilyModel() { Name = dr["ChildName"].ToString() });
}
}
}
return fm;
}
}
Here is some source code that should get the right idea across. Below it, I've included some explanation for what's going on.
using Dapper;
public class FamilyModel
{
public int Id { get; set;}
public string FamilyName { get; set; }
public List<Person> Members { get; set; } = new List<Person>();//Initializer for Auto-Property, C#6<= only
}
public class Person
{
public int Id { get; set;}
public string Name { get; set; }
}
public class DatabasePOCO
{
public string FamilyName { get; set; }
public string ChildName { get; set; }
public int Fid { get; set; }
public int Id { get; set;}
}
void Main()
{
using (IDbConnection conn = new SqlConnection("..."))
{
conn.Open();
var raw = conn.Query<DatabasePOCO>("sp_GetFamilies",
commandType: CommandType.StoredProcedure);//Could be dynamic, not typed
var familyList = raw
.GroupBy(x => x.Fid)
.Select(x =>
{
var rawMembers = x.ToList();
var fId = x.First().Fid;
var fName = x.First().FamilyName;
var members = rawMembers.Select(y => new Person
{
Id = y.Id,
Name = y.ChildName
});
return new FamilyModel
{
Id = fId,
FamilyName = fName,
Members = members.ToList()
};
});
//Whatever else you want to do here
}
}
Consider using Dappper. It is a great ORM that makes accessing data from database really easy. It's designed to work with SQL Server, but I've had success using Oracle too, and most other RMDBS systems will probably work.
Consider using Slapper. If you have control over your stored procedure, this can reduce a lot of the boilerplate code below.
If you use Dapper (I hope you do), you can play around with C# dynamic objects, or you can create a POCO to help get some type enforcement on your code.
Understand if you care about reference equality. The code I provided below does not enforce reference equality of objects. Reference equality, in my experience, doesn't buy you much and is a pain to enforce.
You need to distinguish between a new row in the data set and a new FamilyModel. One way to do this is to declare a list of models, then look up the "right" one before you add the current child row:
var rootModel = new FamilyModel();
rootModel.Name = "root";
// ... Set up data reader ...
while (dr.Read())
{
//This requires support for the Id in your FamilyModel:
var id = (int)dr["Id"];
//You could also use ".Single(...)" here
var fm = rootModel.FamilyList.Where(x => x.Id == id).First();
if (fm == null)
{
fm = new FamilyModel();
fm.Name = dr["FamilyName"].ToString();
rootModel.FamilyList.Add(fm);
}
fm.FamilyList.Add(new FamilyModel() { Name = dr["ChildName"].ToString() });
}
For each row in your database query, you'll:
Try to look up that family in your list
If you don't find one, create a new one. Add it to your top-level list.
Add the child name as a sub-element of the "current" family.
Looking for an example where I can filter my collection based on some filtering criteria.
I have been looking for some example where given a list /array i can filter a collection.
In the example below in my find method I am trying to filter based on 2 values ,looking for something like an "IN" function any suggestions?
class Program
{
static void Main()
{
//Print all customres that belong to below deparments and match on surname
var criteria=new Criteria
{
Departments = new List<string> {"BusinessAnalyst", "Account"},
Surname = "Bloggs"
};
List<Customer> customers = Repository.Find(criteria);
customers.ForEach(x => Console.WriteLine(string.Format("Surname: {0} Department :{1}", x.Surname,x.Department)));
Console.Read();
}
}
public class Repository
{
public static List<Customer>GetCustomers()
{
return new List<Customer>
{
new Customer { Name = "Jon",Surname="Smith",Department = DepartmentType.Managers},
new Customer{Name = "Bill",Surname = "Gates",Department = DepartmentType.Managers},
new Customer { Name = "Mary",Surname = "Bug",Department = DepartmentType.Developers},
new Customer { Name = "Mark",Surname="Boo",Department = DepartmentType.Account},
new Customer{Name = "Ron",Surname = "Scott",Department = DepartmentType.Managers},
new Customer { Name = "Jonny",Surname = "Dip",Department = DepartmentType.Developers},
new Customer { Name = "Mary",Surname = "Bloggs",Department = DepartmentType.BusinessAnalyst},
new Customer { Name = "Mary",Surname = "Bug",Department = DepartmentType.Account},
new Customer { Name = "Jonny",Surname = "Dip",Department = DepartmentType.Account},
new Customer { Name = "Mary",Surname = "Bloggs",Department = DepartmentType.Managers}
};
}
public static List<Customer> Find(Criteria criteria)
{
List<Customer>customers=Repository.GetCustomers();
//Filter on departments
//ERROR HERE AS I cannot do this "IN" would be fantastic.
customers = customers.Contains(criteria.Departments);
//now filter on name
customers = customers.Where(x => x.Surname == criteria.Surname).ToList();
return customers;
}
}
public enum DepartmentType
{
Account,
Managers,
Developers,
BusinessAnalyst
}
public class Customer
{
public string Name { get; set; }
public string Surname { get; set; }
public DepartmentType Department { get; set; }
}
public class Criteria
{
public Criteria()
{
Departments=new List<string>();
}
public string Name { get; set; }
public string Surname { get; set; }
public List<string> Departments { get; set; }
}
public static List<Customer> Find(Criteria criteria)
{
List<Customer> customers = Repository.GetCustomers();
var customers2 = customers.Where(x => criteria.Departments.Contains(x.Department.ToString()));
var customers3 = customers2.Where(x => x.Surname == criteria.Surname);
return customers3.ToList();
}
But considering you use an enum for the Department (DepartmentType), shouldn't your Criteria class use the same instead of a string?
If you define the criteria.Departments as List<DepartmentType> then you can write
public static List<Customer> Find(Criteria criteria)
{
List<Customer> customers = Repository.GetCustomers();
var customers2 = customers.Where(x => criteria.Departments.Contains(x.Department));
var customers3 = customers2.Where(x => x.Surname == criteria.Surname);
return customers3.ToList();
}
Contains returns a bool defining whether a specified object is contained in a collection. Based on your example, you will need to use Where to filter the customers, then use Contains on the departments:
customers = customers.Where(c => criteria.Departments.Contains(c.Department));
i think you want something like this..
customers = customers.Where(c => criteria.Departments.Contains(c.Department));
You want
Customers.Where(c => criteria.Departments.Contains(c.Department.ToString()))
Not sure if this is what you're looking for but the following:
List<Customer> FilteredCustomers = (from c in customers where Criteria.Departments.Contains(c.deparment) && c.surname == Criteria.Surname select c).ToList();
Would equate to something like this in SQL:
SELECT *
FROM Customers
WHERE Department IN (
List of departments
)
AND Surname = surname
I haven't tested this but I think it should work and bring back what you want.