如何合并两个不同对象的列表？

Question

I have two Data Entity Classes of different objects like-

class UserDetails
{
   int Id,
   DateTime DoB,
   string Name,
   .....
   .....
   .....
}

class Documents 
{
   int Id,
   int UserIdFK,
   string ImagePath,
   .....
   .....
}

I am fetching data from below LINQ query-

var UserInfo = (from UserDetail in _userDBContext.UserDetails
                                             join doc in _userDBContext.Documents on UserDetail.Id equals doc.UserIdFK
                                             select new { UserDetail, doc }).ToList();

Now I get data in UserInfo List but data is in 2 rows, 1st row for UserDetails & 2nd one for Documents, how can I merge them (userInfo & Document data) into one single list, having only one row. So that I could use that list in Razor Pages(Front end).

I even created another object & then tried to Convert UserInfo List items into new list but unable to do so, what are the ways to get selected objects of both tables into one single list. Please help me to find an elegant solution.

    public class UserKycCompositeModel
    {
       int Id,
       DateTime DoB,
       string Name,
       .......
       .......
       .......
       int Id,
       int UserIdFK,
       string ImagePath,
       .........
       .........
       .........
  }

Answer 1

If there is a many-to-one relationship between the Documents class and the UserDetails class (meaning that a UserDetails class can have multiple Documents ), then it would be better to give the UserDetails class a list of Documents

Add a List<Documents> to the UserDetails class:

public class UserDetails
{
    public List<Documents> Documents { get; set; }
}

Select the unique UserDetails first:

var userDetails = from ud in _userDBCOntext.UserDetails
                  select ud;

This will result in an IEnumerable<UserDetails> . Loop through that IEnumerable and get all the Documents for each UserDetails instance:

foreach (var userDetail in userDetails)
{
    userDetail.Documets = from doc in _userDBContext.Documents
                          where userDetail.Id equals doc.UserIdFK
                          select doc;
}

Now you have an IEnumerable<UserDetails> (named userDetails ) that has all of the Documents that correspond to it.

Answer 2

It is always better to have a specific ViewModel created to bind it to the View. Window's answer from above should work for you. If you still want to have a generic list instead, a slight tweak to the query should help you out.

    var UserInfo = (from UserDetail in _userDBContext.UserDetails
                    join doc in _userDBContext.Documents 
                    on UserDetail.Id equals doc.UserIdFK
                    select new
                    {
                        UserId = UserDetail.Id,
                        DoB = UserDetail.DoB,
                        Name = UserDetail.Name,
                        DocId = doc.Id,
                        doc.UserIdFK,
                        doc.ImagePath
                    }).ToList();

Answer 3

Select the specific object properties into your composite object:

List<UserKycCompositeModel> userKycCompositeModels = (from UserDetail in _userDBContext.UserDetails
    join doc in _userDBContext.Documents on UserDetail.Id equals doc.UserIdFK
    select new UserKycCompositeModel { UserDetail.Id, UserDetail.Dob, **...etc.** }).ToList();

Answer 4

Because var UserInfo is a List. You cant/should create an object with properties that are not defined.

If you persist with this approach you can create the anonymus object with the way that arun Mohan say.

new {
   UserId = UserDetail.Id,
   DoB = UserDetail.DoB,
   Name = UserDetail.Name,
   DocId = doc.Id,
   doc.UserIdFK,
   doc.ImagePath
}

I don't recomend to use a new class UserKycCompositeModel as that way, but is better (as performance and controling) that having dynamic objects.

Another thing if you want to avoid calling each property (like UserID = UserDetail.ID) is using reflection something like this:

UserKycCompositeModel newObj = new UserKycCompositeModel();

foreach (var item in yourObject.GetType().GetProperties(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.DeclaredOnly))
{
    propertyValue = item.GetValue(yourObject, null);
    Type myType = typeof(newObj);                   
    PropertyInfo myPropInfo = myType.GetProperty(item.Name);
    myPropInfo.SetValue(this, value, null);
}

There are a lot of ways, I believe, not to do exactly what you want, but depending on how you will use it in your logical business you can do it in a different way.

I prefer to do:

public class UserKycCompositeModel
{
    public UserKycCompositeModel(UserDetails ud,Documents  doc)
    {
        this.UserDetails = ud;
        this.Document = doc;
    }
    public UserDetails UserDetails {get; private set;}
    public Documents Document {get; private set;}

}

And after that call in this way:

var UserInfo = (from UserDetail in _userDBContext.UserDetails
                     join doc in _userDBContext.Documents on UserDetail.Id equals doc.UserIdFK
                     select new UserKycCompositeModel(UserDetail, doc)).ToList();

And use user info like UserInfo.UserDetails or UserInfo.Documents.

There are more ways but maybe you have to explain why you want it toghter, or looks if you want to follow the normal way to use entities.