First time posted long time reader. I've done a lot of searching and haven't been able to find anything so please excuse me if I missed a past post or something.
In any case I used to be a .net dev and now getting back into .net core MVC. New to MVC and really liking it!
In any case my question is this... is it possible to use a view model to consolidate data? Basically I am writing a timeline from multiple sources taking only the date stamp and description from each. I am hoping to consolidate all into a timeline viewmodel, but not sure if this is appropriate.
EX:
public class order {
public guid id {get; set;}
public datetime orderDate {get; set;}
public string orderDetail {get; set;}
public int orderQuantity {get; set;}
...
}
public class goodsReceipts {
public guid id {get; set;}
public datetime receiptDate {get; set;}
public int receiptQuantity {get; set}
public order order {get; set;}
...
}
public class otherTransactionaldata {
... there are many different transactions such as goodsreceipt
}
then my view model something like this
public class transactions {
public date transactionDate {get; set;}
public string transactionDetail {get; set;}
}
So I basically want to load all transactional data such as (orders, receipts, returns...) into the view model to create a sorted timeline. Am I going down the wrong path here?
Again sorry for the dumb question. I've been reading like crazy and I'm sure I've missed something so I apologize in advance.
Thank you,
E
Related
I have the following models
public class Student
{
public int Id {get; set; }
public string Name {get; set; }
public ICollection<StudentToCourse> StudentToCourse {get; set; }
}
public class StudentToCourse
{
public int StudentId{get; set; }
public Student Student {get; set; }
public int CourseId{get; set; }
public Course Course {get; set; }
}
public class Course
{
public int Id {get; set; }
public string Name {get; set; }
public ICollection<StudentToCourse> StudentToCourse {get; set; }
}
I want to get a list of all COURSE per student ID, how do I go about doing that?
Short answer: SELECT and match on the Id values. Or programatically -
foreach(Student s in yourstudentList)
{
foreach(StudentToCourse stc in s.StudentToCourse)
{
if(stc.StudentId = s.Id)
//this is one you want, do something with it
}
}
Better answer:
First let's look at your model...
Imagine the underlying database structure.
Your middle table is known as a lookup.
You don't really need the entire Student, nor the entire Course object in it.
Also, your Course object does not need to know about either of the other objects.
If you can imagine three tables in your database you can see how you would logically connect a Student to a Course across the three tables.
Your model is still incomplete though. Within your application you still need a container, in this case a List courseIds. In this way your Student doesn't need to care about all the entries in the Student/Course lookup table, just the ones applicable to the particular Student. And you have an easily accessible object to pull data from, or send updates to, the database.
On initial population of the courseIds collection you would do a
SELECT FROM StudentToCourse where StudentId = x
You can then JOIN on your Course table to pull values such as the Course name.
If you find you need to do a lot of those look ups you may cache your Course list and lower your database traffic at the cost of some ram.
Each time you make a new student you would want to populate their list of course Ids and when committing the student to the database you would save your look up table.
This keeps your objects as lightweight as possible while maintaining their relationships.
There are various ways to write the SELECT statement in your dev environment, search them out and find one you like (or that matches your company's current practices) and get used to consistently using the same one. It will keep your code more readable and manageable.
I have a project where most of the globalization Information is stored in the resx. files and Dataannotations are extensively used.
But now there is a new Poco class which has a text which needs to be localized. What is the best method to do this?
I would do it like this:
public class example
{
public int ItemID {get; set;}
public string Description_en_US {get; set;}
public string Description_de_DE {get; set;}
}
My main concern is how to use this later on in the razor webpage, maybe I will build a method who select a column depending on the thread locale - or does some better mechanism exist?
I have a requirement like this,
Making fields in model as read or write basing on different roles
Suppose in a model i have 15 fields then
User1 with Role1 can edit {Fields 1 to 5; but can view(read only) Fields 6 to 15 } and
User2 with Role2 can edit {Fields 4 ,5,6; but can view(read only) Fields 1 to 3 , 7 to 15}
I googled a lot but i could not find solution
I found a link
http://www.codeproject.com/Tips/403921/Field-Based-Security-in-ASP-NET-MVC-3-for-Differen
but using articles we have to create edit templates for different controls to make it read / write
This is one of major task in the project.
Do you have any solution for this.
Thanks,
Vijay
I don't know if you ever came up with a solution to this and I'd be curious to hear if you did, but for anyone else that stumbles upon this question what I ended up doing was passing a list of the name of all the fields a user has read only access with the view model, and then in my cshtml page I check if the field is part of that list and disable the input tag based on that.
public class DataFields{
public string Field1 {get; set;}
public string Field2 {get; set;}
public string Field3 {get; set;}
public string Field4 {get; set;}
public string Field5 {get; set;}
}
public class DataFieldsViewModel{
public DataFields DataFields {get; set;}
public IEnumerable<string> ReadOnlyFields {get; set;}
}
And then on my cshtml page something like this:
#var isField1ReadOnly = Model.ReadOnlyFields.Contains(nameof(Model.DataFields.Field1));
#var isField2ReadOnly = Model.ReadOnlyFields.Contains(nameof(Model.DataFields.Field2));
#var isField3ReadOnly = Model.ReadOnlyFields.Contains(nameof(Model.DataFields.Field3));
#var isField4ReadOnly = Model.ReadOnlyFields.Contains(nameof(Model.DataFields.Field4));
#var isField5ReadOnly = Model.ReadOnlyFields.Contains(nameof(Model.DataFields.Field5));
...
<input asp-is-disabled="#(isField1ReadOnly)" asp-for"Model.DataFields.Field1">
<input asp-is-disabled="#(isField2ReadOnly)" asp-for"Model.DataFields.Field2">
asp-is-disabled is based on something like this: https://stackoverflow.com/a/34868369/4573789
Can someone please post an example on how to create a many to many relationship where the source class is also the target one, using code-first ?
Something like:
Toys * <-----> * Toys
Thank you.
Nuno Senica
I don't think this is possible with EF Code First. As a workaround, you could create the mapping table yourself:
public Toy
{
public int ToyID {get; set;}
public ICollection<ToyMapping> Toys {get; set;}
}
public ToyMapping
{
public int ToyOneID {get; set;}
public int ToyTwoID {get; set;}
public ICollection<Toy> ToyOnes {get; set;}
public ICollection<Toy> ToyTwos {get; set;}
}
I'm not sure the actual use-case for this is, otherwise I would have made better named properties.
let's say we have something like this
public class Person
{
public string Name {get; set;}
public Country Country {get; set;}
}
public class PersonViewModel
{
public Person Person {get; set;}
public SelectList Countries {get; set;}
}
can automapper be used to perform to parse from Person into PersonViewModel and back ?
Don't use AutoMapper for this - it's not worth it. For example, in the cases where you have a validation failure and you show the form again - AutoMapper is not executed here (usually). We usually go two routes:
If the list is not context-specific, create an HtmlHelper that queries some ISelectListProvider for the select list items: Html.DropDownList(). You'd use your IoC container of choice to locate the personListProvider, query for the list of items, and populate the dropdown list.
If the list is context-specific, just construct the list in the controller action
It sounds like you want to send a Person to the view via the PersonViewModel which has all the bonus info you need to generate and return a new (or updated) Person object.
If this is correct, I don't think you need automapper at all. From what I understand of automapper it is for mapping collection of related objects to a more view model type of state, but in this case, you are sending a Person to the client and trying to receive a Person back. In this case, it seems easier to use your view model to populate the page, but have the page return a Person instead (or extract the updated Person from the view model to save a few keystrokes).
EDIT: That being said, yes you should be able to use automapper to move the info around. Its just a unnecessary layer for this easy scenario.
if one chose to, you could do this:
public class Person
{
public string Name {get; set;}
public Country Country {get; set;}
public Country[] GetCountries
{
... add method for countries here
}
}
Then in your ViewModel you can have your select list pull data from that collection.
public class PersonViewModel
{
public Person Person {get; set;}
public Country[] Countries {get; set;}
public SelectList Countries { get{ .. add new select list code here getting vals from Countries..}}
}
Again, this is for context sensitive lists. You are however muddling concerns a wee bit here (should a person get a list of countries?)