I have two entities: Person and Quote (in one to many relationship)
Person:
public class Person
{
public int PersonID { get; set; }
[Required]
[StringLength(20]
public string Name { get; set; }
[StringLength(30]
public string Relation { get; set; }
public byte[] Image { get; set; }
[StringLength(50)]
public string ImageMimeType { get; set; }
public virtual ICollection<Quote> Quotes { get; set; }
}
Quote:
public class Quote
{
public int QuoteID { get; set; }
public int PersonID { get; set; }
[Required]
[StringLength(200)]
public string QuoteName { get; set; }
[StringLength(400)]
public string Context { get; set; }
public DateTime? Date { get; set; }
public virtual Person Person { get; set; }
}
I want to make a ViewModel for displaying quotes in short format - I need just a few properties - Person Name, QuoteName and Person Image. I could do something casual like they're showing in every ASP.NET MVC tutorial:
public class QuoteViewModel
{
public IEnumerable<Quote> Quotes { get; set; }
}
Is there a better way rather than creating IEnumerable with type of Quote and loading all properties?
How about creating QuoteShort model and making QuoteViewModel as IEnumerable<QuoteShort> QuotesShort.
In controller I would map every 3 fields from repository to QuoteShort and add it to QuotesShort IEnumerable (even though I don't know how to persist them to QuotesShort IEnumerable )
Some examples appreciated.
You can make a QuoteShort ViewModel with just the few properties you need, and then have your view expect IEnumerable<QuoteShort> as its model. You don't necessarily have to wrap that up in another container.
If you have this:
public class QuoteShort{
public Person Person {get;set;}
public string Name {get; set;}
// etc
}
You can do this in the controller:
var quotes = //however you get your list of quotes
var model = (from q in quotes select new QuoteShort
{ Person = q.Person, Name = q.Name /*etc*/ }).ToList();
return View(model);
What about something like
public class QuotesShortViewModel
{
public IEnumerable<QuoteShortViewModel> QuotesShort { get; set; }
}
public class QuoteShortViewModel
{
// ... the properties you need
}
Create a View that receives a QuotesShortViewModel and iterates through the list, rendering the short quotes as it pleases you.
AutoMapper is useful to map between Models and ViewModels in your controllers.
Related
Having an issue with projection and getting child objects to load. The following is simplified code to represent the logic I'm trying to implement, not the actual code.
public class TicketItem
{
public int TicketItemId { get; set; }
public string TicketReason { get; set; }
public Station Station { get; set; }
public TicketOwner TicketOwner { get; set; }
}
public class Station
{
public int StationId { get; set; }
public string Name { get; set; }
}
public class TicketOwner
{
public int TicketOwnerId { get; set; }
public Employee Employee { get; set; }
public Organization Organization { get; set; }
}
public class Employee
{
public int EmployeeId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
}
public class Organization
{
public int OrganizationId { get; set; }
public string Code { get; set; }
public string Name { get; set; }
}
public class CommonReasons
{
public int CommonReasonId { get; set; }
public string Reason { get; set; }
}
public TicketItem GetById(int id)
{
var query = from i in _dataContext.TicketItems
.Include("Station")
.Include("TicketOwner.Employee")
.Include("TicketOwner.Organization")
join r in _dataContext.CommonReasons on i.TicketReason equals r.CommonReasonId.ToString() into r1
from r2 in r1.DefaultIfEmpty()
where i.TicketItemId == id
select new TicketItem {
TicketItemId = i.TicketItemId,
TicketReason = r2.Reason == null ? i.Reason : r2.Reason,
Station = i.Station,
TicketOwner = i.TicketOwner
};
return query
.AsNoTracking()
.FirstOrDefault();
}
Most the code is self-explanatory. The part that is indirectly causing the trouble would be the relationship between TicketItem.TicketReason property (a string) and the CommonReasons entity. From the user interface side, the end-user has an input field of "Reason", and they can select from "common" reasons or input an adhoc reason. They original developer chose to have the TicketReason property contain either the key ID from the CommonReasons table (if the user selected from drop-down) or the adhoc reason typed in.
So, to handle this logic in the linq query, the only way I have found is to do a left join between TicketItem.TicketReason and CommonReasons.CommonReasonId, then use projection to modify the TicketReason column returning either the common reason text or adhoc text. If there is a different way to do this that would get me around the trouble I'm having with projection/include, I'm all ears.
For the "reason" logic, this query works, returning the proper text. The trouble is that none of the "grand-child" objects are returning, i.e. TicketItem.TicketOwner.Employee, TicketItem.TicketOwner.Organization. How do I get those objects to return also?
Changing the structure of the tables would be an absolute last resort, just based on the amount of code that would have to change. There are other spots in the code that are using the above logic but don't need the child objects.
Any help would be appreciated. Hope I've explained enough.
EDIT: I originally worded this question very poorly, stating the problem was with JSON serialization. The problem actually happens when I'm converting from my base classes to my returned models using my custom mappings. I apologize for the confusion. :(
I'm using .NET Core 1.1.0, EF Core 1.1.0. I'm querying an interest and want to get its category from my DB. EF is querying the DB properly, no problems there. The issue is that the returned category has a collection with one interest, which has one parent category, which has a collection with one interest, etc. When I attempt to convert this from the base class to my return model, I'm getting a stack overflow because it's attempting to convert the infinite loop of objects. The only way I can get around this is to set that collection to null before I serialize the category.
Interest/category is an example, but this is happening with ALL of the entities I query. Some of them get very messy with the loops to set the relevant properties to null, such as posts/comments.
What is the best way to address this? Right now I'm using custom mappings that I wrote to convert between base classes and the returned models, but I'm open to using any other tools that may be helpful. (I know my custom mappings are the reason for the stack overflow, but surely there must be a more graceful way of handling this than setting everything to null before projecting from base class to model.)
Classes:
public class InterestCategory
{
public long Id { get; set; }
public string Name { get; set; }
public ICollection<Interest> Interests { get; set; }
}
public class Interest
{
public long Id { get; set; }
public string Name { get; set; }
public long InterestCategoryId { get; set; }
public InterestCategory InterestCategory { get; set; }
}
Models:
public class InterestCategoryModel
{
public long Id { get; set; }
public string Name { get; set; }
public List<InterestModel> Interests { get; set; }
}
public class InterestModel
{
public long Id { get; set; }
public string Name { get; set; }
public InterestCategoryModel InterestCategory { get; set; }
public long? InterestCategoryId { get; set; }
}
Mapping functions:
public static InterestCategoryModel ToModel(this InterestCategory category)
{
var m = new InterestCategoryModel
{
Name = category.Name,
Description = category.Description
};
if (category.Interests != null)
m.Interests = category.Interests.Select(i => i.ToModel()).ToList();
return m;
}
public static InterestModel ToModel(this Interest interest)
{
var m = new InterestModel
{
Name = interest.Name,
Description = interest.Description
};
if (interest.InterestCategory != null)
m.InterestCategory = interest.InterestCategory.ToModel();
return m;
}
This is returned by the query. (Sorry, needed to censor some things.)
This is not .NET Core related! JSON.NET is doing the serialization.
To disable it globally, just add this during configuration in Startup
services.AddMvc()
.AddJsonOptions(options =>
{
options.SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
}));
edit:
Is it an option to remove the circular references form the model and have 2 distinct pair of models, depending on whether you want to show categories or interests?
public class InterestCategoryModel
{
public long Id { get; set; }
public string Name { get; set; }
public List<InterestModel> Interests { get; set; }
public class InterestModel
{
public long Id { get; set; }
public string Name { get; set; }
}
}
public class InterestModel
{
public long Id { get; set; }
public string Name { get; set; }
public InterestCategoryModel InterestCategory { get; set; }
public class InterestCategoryModel
{
public long Id { get; set; }
public string Name { get; set; }
}
}
Note that each of the models has a nested class for it's child objects, but they have their back references removed, so there would be no infinite reference during deserialization?
I have an application that can contain a minimum of one "person" up to a maximum of fours "persons". I am using view models and manually mapping in the controller to the domain model.
I am completely lost as to how to include more than one "person" in the app. I've read up on using for but can't wrap my head around it.
Right now, I am just adding the data from the "person" class manually such that
Code:
public class SomeClass
{
public Guid SomeClassId {get; set;}
public string BorrowerFirst { get; set; }
public string BorrowerMI { get; set; }
public string BorrowerLast { get; set; }
public Suffix? BorrowerSuffix { get; set; }
... some more fields ...
}
and so on in the master class.
What I'd like to do is use a class such as:
Code:
public class Applicant
{
public string BorrowerFirst { get; set; }
public string BorrowerMI { get; set; }
public string BorrowerLast { get; set; }
public Suffix? BorrowerSuffix { get; set; }
}
can be reused in another class multiple times.
How can I separate that to strip that and instead use a named class consisting of first, middle and last names and allowing up to four "person" instances in my master class?
Have you tried inheritance?
public class Person
{
public Guid SomeClassId {get; set;}
public string BorrowerFirst { get; set; }
public string BorrowerMI { get; set; }
public string BorrowerLast { get; set; }
public Suffix? BorrowerSuffix { get; set; }
}
and the Applicant class:
public class Applicant : Person
{
//Only extra properties and methods here.
public string FullName
{
get
{
return this.BorrowerFirst + " " + this.BorrowerMI + " " + this.BorrowerLast;
}
}
}
You can then have a vendor as well:
public class Vendor: Person
{
//Only extra properties and methods here.
}
I have a C# MVC Model as follows;
public class MyModel
{
...
public IEnumerable<MyModel> allDetails { get; set; }
public int age { set; get; }
public string gender { set; get; }
public int schoolid { set; get; }
...
}
Now want to retrieve data from allDetails. How can i do it ?
In the controller;
model.allDetails = MyDetails.getAllDetails(); // Saves all details in the Model
Now how can i retrieve age, gender and school from this model; My approach as follows (but its doesn't work)
model.allDetails.age; // This doesn't work
In your code model.allDetails is a list (or smth else that implements IEnumerable), so you have to use foreach or another loop, or just First() to get first value from it: model.allDetails.First().age
I think you got your desing for class MyModel wrong, You should probably have two classes like:
public class MyClass
{
...
public IEnumerable<MyModel> allDetails { get; set; }
public int age { set; get; }
public string gender { set; get; }
public int schoolid { set; get; }
...
}
public class MyModel
{
...
public IEnumerable<MyClass> allDetails { get; set; }
...
}
Where your MyModel class will contain an IEnumerable of your other class which contains properties. Later you can fill your model through controller.
In your current MyModel class, you are keeping IEnumerable of the class itself, so each object for that class will have another IEnumerable and so on.
You may also see: C# Coding Conventions (C# Programming Guide) for your properties names.
here is the object model.When i try to commit Product to Solr, returning unknown field loca
public class Product
{
[SolrUniqueKey("id")]
public string Id { get; set; }
[SolrField("manu")]
public string Manufacturer { get; set; }
[SolrField("cat")] // cat is a multiValued field
public ICollection<string> Categories { get; set; }
[SolrField("price")]
public decimal Price { get; set; }
[SolrField("inStock")]
public bool InStock { get; set; }
[SolrField("loca")]
public Location Location { set; get; }
}
public class Location
{
[SolrField("zipcode")]
public int Zip { set; get; }
[SolrField("country")]
public string Country { set; get; }
}
Is nested classes legal with solr?
why is it failing to store? when i remove [SolrField("loca")] it works fine.
how do you store such classes?
You cannot do nested classes in Solr. So you will need to flatten the location information into the Product class. However, you can then represent it a nested class within your application, by mapping the data into/out of Solr as needed.
As an example, update your Solr schema to store a loca_zipcode and loca_country field and then map those perhaps in a new SolrProduct class defined like the following:
public class SolrProduct
{
[SolrUniqueKey("id")]
public string Id { get; set; }
[SolrField("manu")]
public string Manufacturer { get; set; }
[SolrField("cat")] // cat is a multiValued field
public ICollection<string> Categories { get; set; }
[SolrField("price")]
public decimal Price { get; set; }
[SolrField("inStock")]
public bool InStock { get; set; }
[SolrField("loca_zip")]
public int Zip { set; get; }
[SolrField("loca_country")]
public string Country { get; set; }
}
Then you can use something like AutoMapper to map the SolrProduct flattened class to your Product class with the nested Location class.
Another alternative would be to use dynamic fields in Solr and the dynamic mapping support in SolrNet using a Dictionary. Please see the SolrNet - Mapping section of the SolrNet wiki for more details and examples.