Getting list in asp.net core from another table

Sushant Torankar

Helllo,

I am new to asp.net core 5.0 web api entity framework, with sql database.

I have two tables LogsMaster with columns Id, title, Description and PermissionMaster with columns Id, LogId and ContactId

When Log details is saved in LogsMaster, along with it I am saving LogId(Primary Id column of LogsMaster) and ContactId in PermissionMaster table. So one LogId can have multiple ContactId in PermissionMaster table.

Using following property in LogsMaster table to save ContactId List
public IEnumerable Contacts { get; set; }

Here I want to fetch List of Logs by LogId, I am getting that list,but Contact is coming as null

so how to bind multiple contact id's for that logid in asp.net core web api ?

sorry, if I'm not able to explain you well ?

thank you

5 Replies

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Sushant Torankar4y ago
i try to understand navigation property, but somehow it is not working in my case or I'm doing something wrong
Following is my table structure

LOGSMASTER Table PERMISSIONMASTER Table
[Key] [Key]
public Guid LogId { get; set; } public Guid Id { get; set; }
public string Title { get; set; } [ForeignKey("LogsMaster")]
public string Description { get; set; } public Guid? LogId { get; set; }
public IEnumerable PermissionMasters { get; set; } public virtual LogsMaster LogsMaster { get; set; }

here I've to get list of Logs, including permission list. Following is my code :
public async Task> GetAllLogs()
{
var posts = await _context.LogsMasters.Include(x => x.PermissionMasters).ToListAsync();
return posts;
}

But it says : SqlException : Invalid column 'LogsMasterLogId'

Both table have LogId column, not sure why it's giving that error.

I am using entity framework core, with database first approach

thank you
Sachin Singh4y ago
@Sushant you can follow my article

https://www.sharpencode.com/article/EntityFramework/how-to-establish-relationship-correctly

This is applicable to both EF and EF Core
Sushant Torankar4y ago
thank you for reply
Sachin, can you plz explain, how should i menton relationship with these tables?
Sachin Singh4y ago
If you are using EF Core then you must have navigation property
use this
var res=_Context.LogsMaster.Include(x=> x.Contacts)
.ToList();
Riccardo Rigutini4y ago
Hi,

is ContactsMaster another table?

Anyway, in Entity Framework related entities are not loaded by default; there are three main ways to load them:
- Eager loading - related data is loaded from the database as part of the initial query.
- Explicit loading - related data is explicitly loaded from the database at a later time.
- Lazy loading - related data is loaded from the database when the navigation property (Contacts) is accessed.
The documentation shows how to implement these patterns:

https://docs.microsoft.com/en-us/ef/core/querying/related-data/