Get entity by field value in ASP.NET Core 3.1
asp.net-core c# entity-framework-core linq-to-sql repository-pattern
Question
I have used a method like this before to retrieve the entity and It was working perfectly in ASP.NET Core 2.2 Repository (because most of my tables have the CODE property):
public T GetByCode(string code)
{
PropertyInfo pi = typeof(T).GetProperty("Code");
return _context.Set<T>().FirstOrDefault(t => pi.GetValue(t).ToString().Trim().ToLower() == code.Trim().ToLower());
}
But as soon as I changed the framework to .NET Core 3.1 I got error like:
InvalidOperationException: The LINQ expression 'DbSet .Where(c => __pi_0.GetValue(c).ToString().Trim().ToLower() == __ToLower_1)' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to either AsEnumerable(), AsAsyncEnumerable(), ToList(), or ToListAsync().
Popular Answer
Because in EF Core 2.2, you were probably fetching the entire table into memory.
In your case, since all these tables have a Code property, I would recommend adding some form of IHaveCode common interface. Then you can trivially remove all the reflection, which EF Core can't translate to sql;
public T GetByCode<T>(string code) where T:IHaveCode
{
return _context.Set<T>().FirstOrDefault(t => t.Code.Trim().ToLower() == code.Trim().ToLower());
}
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