I have understood the following code
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Student>()
.MapToStoredProcedures(p => p.Insert(sp => sp.HasName("sp_InsertStudent").Parameter(pm => pm.StudentName, "name").Result(rs => rs.Student_ID, "Student_ID"))
.Update(sp => sp.HasName("sp_UpdateStudent").Parameter(pm => pm.StudentName, "name"))
.Delete(sp => sp.HasName("sp_DeleteStudent").Parameter(pm => pm.Student_ID, "Id"))
);
}
But still I have few questions
1. If I have button called calculate and want to call some other procedure apart from CRUD. How can I call that SP?
2. How can I pass list of model/entity (collection) to procedure as parameter? or any other solution.
If you have access to your DbContext class where you want to call the stored procedure, you can simply do:
var studentStuff = dbContext.Database.SqlQuery<Student>
("dbo.DoSomethingWithStudent #studentID",
new SqlParameter("#studentID", studentID));
You can't pass a complex model directly to a SQL stored procedure.
If your procedure returns no results it would be:
dbContext.Database.ExecuteSqlCommand("EXEC dbo.DoSomethingWithStudent #studentID",
new SqlParameter("#studentID", studentID));
Related
How can I save a string in upper case using entity framework.
I'm not looking to override saveChanges method.
What I want is a way to (if I want) apply a transformation to a string saved in a DB column
I've tried this, but it does not work.
builder.Property(self => self.Series)
.HasMaxLength(2)
.HasConversion(ToUpperCaseConvertor())
.IsRequired();
public static ValueConverter<string, string> ToUpperCaseConvertor()
{
return new ValueConverter<string, string>(
prop => prop,
prop => prop.ToUpper());
}
I currently have Sql mapped function which I want to map as a user-defined function:
context.Structures.FromSqlInterpolated($"select * from \"Structures\" where \"Molfile\" # ({search}, '')::bingo.sub")
The where method comes from a PostgreSQL extension called Bingo.
I don't understand from the docs how I should be doing that. Here's an example of the things I've tried:
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
builder.Entity<Structure>().ToTable("Structure");
builder.HasDbFunction(typeof(ChemistryContext).GetMethod(nameof(Sub), new[] { typeof(string) })).HasName("bingo.sub");
}
public IQueryable<Structure> Sub(string search)
=> FromExpression(() => Sub(search));
This particular code above fails because there's no bingo.sub user function.
Thank you for some inputs on how this should be done!
I have this value object
public class ProductReference : ValueObject
{
protected ProductReference(){}
public ProductReference(string value){}
public string Value{get; protected set;}
}
I use it in my entity as :
public class Product : Entity<long>
{
protected Product(){}
public ProductReference Reference{get; protected set;}
}
In the OnModelCreating of my DbContext I defined :
modelBuilder.Entity<Product>(entity => {
entity.Property(a => a.Reference)
.HasColumnName("Reference")
.HasConversion(
a => a.Value,
s => new ProductReference (s);
});
When I do :
await dbcontext.Products.Where(p=>p.Reference.Value.Contains("some text")).toArrayAsync();
I get an exception
Expression cannot be converted to a valid SQL statement
I know for sure there is a way to create a custom expression converter, but I cannot find a good, simple and EF Core 3.1 compatible example to deal with my issue and that explain me clearly the concepts I miss.
I found this very interesting project
https://github.com/StevenRasmussen/EFCore.SqlServer.NodaTime
but it is too advanced for me to reproduce it for only my use case.
[EDIT] the ValueObject ans Entity are from
CSharpFunctionalExtensions nuget package, I dont think they are really relevant in my question.
I am not completely sure if i understand correctly what you want to accomplish, but you could try to configure your ProductReference as an Owned Entity Type.
Here you would transform the following code from:
modelBuilder.Entity<Product>(entity => {
entity.Property(a => a.Reference)
.HasColumnName("Reference")
.HasConversion(
a => a.Value,
s => new ProductReference (s);
});
to
modelBuilder.Entity<Product>(entity => {
entity.OwnsOne(a => a.Reference, referenceBuilder => {
referenceBuilder.Property(p => p.Value).HasColumnName("Reference");
});
});
With that your select statement should work.
It could be that you have to play around with the properties of your class ProductReference, or use some modifiers of the fluent API.
So first for some context on what is happening here behind the scenes and why its not gonna work even for build in simple converters like BoolToZeroOneConverter.
The problem here is that you are calling when converting the new ProductReference(s). This is method where you can do whatever you want in it. For example if use it in a Select statement it will again fail. For example:
await dbcontext.Products
.Select(x=>new ProductReference(x.Value))
.toArrayAsync();
The reason is obvious, it won't be able to translate. But why it cant transform it to a query?
Because you are passing a constructor. Inside this constructor you could be doing API calls or using Reflections to set the variables to your object, pretty much anything. That of course is not able to be translated in an SQL query.
Converters are generally used for in memory but they can be used for databse operations as well. This would mean that you will need something like this:
await dbcontext.Products
.Select(x=>new ProductReference() // empty constructor that does nothing
{
Property1 = x.Property1 // I don't know how the constructor maps them
})
.toArrayAsync();
Using this type of expression allow you to actually transalte the expression to an SQL statement and not making the conversion on the SQL DB and not in memory.
Now in your specific case using:
.HasConversion(
a => a.Value,
s => new ProductReference (){};
});
Should fix your issues but I fail to understand why would you want to initialize or convert a ProductReference to a ProductReference.
I will state up front I am still very new to asp.net core and entity framework but I am familiar with ADO and recordset which it seems entity framework is built from. I am struggling to use entity framework because I am able to run the query but I am not sure how to use the results and most help docs I see online only discuss the procedures and methods and not how to use the results. I am building login functionality on my site and have developed the following code to query DB in my UserAccount table. FOr this login I really only want the Username, Password, and the ID however I have multiple fields in this table that I dont need for this aspect. I come from using ADO and recordsets so really I just prefer to use raw sql and determine what i want to do with those results and not bind them to some objects which it seems entity framework does for the most part. I do liek the ease of use of the entity framework and using parameters though so I prefer to just go this route (not sure if this is bad practice or not). Everything works great except when I add ToList it starts to say error "InvalidOperationException: The required column 'AccessLevel' was not present in the results of a 'FromSql' operation." I am not even tryign to use that field in the query so not sure why that is even coming up and I am using a rawsql query method so why is it trying to see what I have in the model for that table? Lastly, this shoudl return a single record in which case I want to pull the password value from that record field similar to how i use to do in ADO as you will see in my passwordhash verification but I cannot figure out how to even pull that from the query result. Thanks for any help on this as I am getting a headache trying to learn this stuff!!
var UserResults = _context.UserAccounts.FromSqlInterpolated($"SELECT USERACCOUNT.USERNAME, USERACCOUNT.PASSWORD, USERACCOUNT.ID,USERACCOUNT.ACCESS_LEVEL FROM DBO.USERACCOUNT WHERE USERACCOUNT.USERNAME={UserName}");
if (UserResults.Count() == 1) //if we have more than 1 result we have security issue so do not allow login
{
var passwordHasher = new PasswordHasher<string>();
var hashedPassword = passwordHasher.HashPassword(null, Password);
var testResults = UserResults.ToList();
if (passwordHasher.VerifyHashedPassword(null, hashedPassword, THIS SHOULD BE VALUE FROM DB RIGHT HERE!!!) == PasswordVerificationResult.Success)
{
var claims = new List<Claim>
{
new Claim(ClaimTypes.Name, UserName)
};
My DBContext is as follows:
public partial class LoginDBContext : DbContext
{
public DbSet<UserAccount> UserAccounts { get; set; }
public LoginDBContext(DbContextOptions<LoginDBContext> options) : base(options)
{
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<UserAccount>(entity =>
{
//entity.ToTable("UserAccount");
entity.HasNoKey();
//entity.Property(e => e.Id)
// .HasMaxLength(50)
// .IsUnicode(false);
//entity.Property(e => e.Username)
// .HasMaxLength(50)
// .IsUnicode(false);
//entity.Property(e => e.Password)
// .HasMaxLength(50)
// .IsUnicode(false);
});
}
}
If you don't want to load all columns of the user table you can return anonymous object with properties you need or create a class for the columns you need and return it.
var users = _context.UserAccounts
.Where(a => a.UserName == UserName)
.Select(a => new { a.Id, a.UserName, a.Password })
.ToArray();
if (users.Length == 1)
{
var user = users.First();
if (passwordHasher.VerifyHashedPassword(null, hashedPassword, user.Password) == PasswordVerificationResult.Success)
{
// ... your magic
}
}
I have an EF model with a notification emails property. The notification emails are saved in the database as string separated by ';'. I added a conversion to retrieve the data as a ICollection in the model. This is working well except one thing: when the string is null the collection is also null, and I want to convert it to an empty collection instead. is it possible?
//This is my code
entity.Property(e => e.NotificationEmails)
.HasConversion(
v => string.Join(",", v.Select(s => s.Trim())),
v => v.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries));
I tried to add String.IsNullOrEmpty(v) but EF ignores it.
Currently, it isn't possible :
https://learn.microsoft.com/en-us/ef/core/modeling/value-conversions#configuring-a-value-converter
A null value will never be passed to a value converter. This makes the implementation of conversions easier and allows them to be shared amongst nullable and non-nullable properties.
It isn't elegant, but you can use a backing field :
public class Notification
{
private List<string> _emails = new List<string>();
public List<string> Emails
{
get => _emails;
set => _emails = value ?? new List<string>();
}
}
public class NotificationContext : DbContext
{
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Notification>().Property(d => d.Emails).HasConversion(
v => string.Join(",", v.Select(s => s.Trim())),
v => v.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries).ToList()
);
modelBuilder.Entity<Notification>()
.Property(b => b.Emails)
.HasField("_emails")
.UsePropertyAccessMode(PropertyAccessMode.Property);
}
}
Note : in where, a empty list will not be translated by null, but by a empty string.
Edit : This feature is available from EF Core 6, but bugged.
See this comment :
For anyone watching this issue: there are significant problems when executing queries that either convert nulls in the database to non-nulls in code or vice-versa. Therefore, we have marked this feature as internal for EF Core 6.0. You can still use it, but you will get a compiler warning. The warning can be disabled with a #pragma.