I'm trying to set up an API for a system I'm working on, but the LINQ seems to not grab the parameters.
A bit of background: During covid I've been working with a local business owner to develop an info system for his business. So far, everything has been kept in the browser, but now we want to create a small windows form application the users can download instead of using the browser. The application will be much smaller in scope than the full site, but I don't want the SQL connection in the form.
So I guess my first question is, am I being overly cautious at not wanting the SQL connector in the client and wanting them to connect to the database, via an API, or is it safe enough to add the connection and calls directly in the application (I know how to do this, it's the API part I can't figure out). I'm thinking about it from a security point of view - would the users be able to find the connection and potentially do harm to my database by having it straight in the application or is it safe there?
If using API calls is the proper way to go, that leads me to my second question. How do I configure it properly?
This is my table (I've been following the Microsoft ToDoItems tutorials):
CREATE TABLE [dbo].[TodoItems] (
[Id] [int] identity(1,1) NOT NULL,
[Name] [nvarchar](50) NULL,
[IsComplete] [bit] NULL,
[Secret] [nvarchar](10) NULL
) ON [PRIMARY]
GO
My test form has a single button, which when pressed calls this method:
static async Task RunAsync()
{
// Update port # in the following line.
client.BaseAddress = new Uri("https://localhost:7217/");
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(
new MediaTypeWithQualityHeaderValue("application/json"));
try
{
// Create a new product
TodoItem product = new TodoItem
{
Name = "Gizmo",
IsComplete = false,
Secret = "false"
};
var url = await CreateProductAsync(product);
Console.WriteLine($"Created at {url}");
// Get the product
product = await GetProductAsync(url.PathAndQuery);
ShowProduct(product);
// Update the product
Console.WriteLine("Updating IsCompleted...");
product.IsComplete = true;
await UpdateProductAsync(product);
// Get the updated product
product = await GetProductAsync(url.PathAndQuery);
ShowProduct(product);
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
}
My ToDoItem class looks like this:
public class TodoItem
{
public long Id { get; set; }
public string Name { get; set; }
public bool IsComplete { get; set; }
public string Secret { get; set; }
}
My first issue is creating the ToDoItem. This method should do the trick:
static async Task<Uri> CreateProductAsync(TodoItem product)
{
HttpResponseMessage response = await client.PostAsJsonAsync(
"api/todoitems", product);
response.EnsureSuccessStatusCode();
// return URI of the created resource.
return response.Headers.Location;
}
However, when I run the method my API logs this error and nothing is posted to the database:
Executed DbCommand (46ms) [Parameters=[#p0='?' (DbType = Boolean), #p1='?' (Size = 4000), #p2='?' (Size = 4000)], CommandType='Text', CommandTimeout='30']
SET NOCOUNT ON;
INSERT INTO [TodoItems] ([IsComplete], [Name], [Secret])
VALUES (#p0, #p1, #p2);
SELECT [Id]
FROM [TodoItems]
WHERE ##ROWCOUNT = 1 AND [Id] = scope_identity();
The way I read this, and I might be wrong, the method CreateProductAsync (which gets a product with the values "Gizmo", false and "false") simply doesn't transfer the values to the API.
For reference, my API ToDoContext class look like this:
public class TodoContext : DbContext
{
public TodoContext(DbContextOptions<TodoContext> options)
: base(options)
{
}
public DbSet<TodoItem> TodoItems { get; set; } = null!;
}
Do I need to add something to this class? I'm wholly unfamiliar with both API and LINQ, but I did figure out that changing the table name to ToDoItems made the connection for me on its own.
Related
So I am kind of new to Web services, and I am trying to wrap my head around how it works.
Basically, I need to receive an ID from one side, pass it to another source which returns the employee information.
Now, this is what I did so far:
[WebMethod(Description = "Returns employee object for id")]
public Employee GetEmployeeById(int Id)
{
// how to ?
return new Employee( // data from outer source);
}
I see the wsdl, where you can send the id to the function.
How does the other source get the information from my service?
The another source means that anywhere you want to connect to. Maybe it's a database, other web service, or only a text file....
For example, you have a db that saves employee data. You can use Entity Framework to get employee data from db.
Like this:
[WebMethod(Description = "Returns employee object for id")]
public Employee GetEmployeeById(int Id)
{
using(var context = new MyDbContext())
{
var emp = context.Employees.Where(x => x.Id == Id).FirstOrDefault();
return emp;
}
}
So, I tried searching and couldn't really find an answer that was explicit enough and guided me to my solution so I thought I would add my problem and ultimately my solution for others to benefit.
Pardon my newness to SO (consider this my start of getting my reputation up), let me know if I do anything incorrect or forget anything.
I am trying to:
Create a controller that queries a database for all the users and their roles.
Return the list of unique users id's and email address with a List of roles.
The email address and roles are in separate tables and the pkey/fkey is the user id
The roles are returned as a list containing my AllUserInRolesDto
Every example I looked at on SO or other sites only provided examples of returning anonymous data objects back. I don't have a lot of LINQ query syntax so had me stuck for an hour or so.
Here is my DTO
namespace Lib.Dtos
{
public class AllUserInRolesDto
{
public string FullName { get; set; }
public string Email { get; set; }
public List<RoleDto> Roles { get; set; }
}
public class RoleDto
{
public string RoleName { get; set; }
}
}
I have a business layer that defines the LINQ query
public List<AllUserInRolesDto> UserAllRolesGet()
{
List<AllUserInRolesDto> getAllUsersRoles = (from u in _context.Users
join r in _context.UserInRoles on u.UserId equals r.UserId
into ur
select new Lib.Dtos.AllUserInRolesDto()
{
FullName = u.Fullname,
Email = u.Email,
Roles = ur //this was the problem line and what the docs were describing
}).ToList();
return getAllUsersRoles;
}
...and my controller
[HttpGet("GetAllUserRolesList")]
public IActionResult GetAllUserRolesList()
{
List<Lib.Dtos.AllUserInRolesDto> allUsers = _userBL.UserAllRolesGet();
return new JsonResult(allUsers);
}
my solution
After taking a step back for a second I realized I actually wasn't returning the right object back to my roles property...and so need to iterate over my roles and create a list from them. Here is what worked.
public List<AllUserInRolesDto> UserAllRolesGet()
{
List<AllUserInRolesDto> getAllUsersRoles = (from u in _Context.Users
join r in _context.UserInRoles on u.UserId equals r.UserId
into ur
select new Lib.Dtos.AllUserInRolesDto()
{
FullName = u.Fullname,
Email = u.Email,
Roles = .Select(x => new Lib.Dtos.RoleDto() { RoleName = x.RoleName }).ToList() //Changed to this
}).ToList();
return getAllUsersRoles;
}
Anyway, probably a pretty dumb mistake, but had me stuck for a bit. Maybe this helps someone in my same position or if someone has a comment of how I could have improved this or used a different approach I am open to hearing suggestions.
I assume you're using Entity Framework, and that you have your DB model defined with relationships. This means you don't need to use explicit JOINs in your queries: you can use navigation properties instead.
Your "business layer" (note that you don't necessarily always need a business layer) should only work with Entity types and should not use DTOs (as DTOs belong to your web-service, in the same way that View-Models belong to a web-application).
If your "business layer" just consists of predefined queries, I recommend defining them as static extension methods for your DbContext and returning IQueryable<T> instead of as materialized List<T> as this enables your consumers to perform further operations on them (such as additional filtering or sorting and paging).
I recommend doing it like this instead:
// Queries methods (i.e. "business layer" queries)
public static class QueriesExtensions
{
public static IQueryable<User> GetAllUsersAndTheirRoles( this MyDbContext db )
{
// I assume `UserInRoles` is a linking table for a many-to-many relationship:
return db
.UserInRoles
.Include( uir => uir.User )
.Include( uir => uir.Role )
.Select( uir => uir.User );
}
}
// Web-service controller:
[HttpGet("GetAllUserRolesList")]
[Produces(typeof(List<AllUserInRolesDto>)]
public async Task<IActionResult> GetAllUserRolesList()
{
List<User> usersList = await this.db
.GetAllUsersAndTheirRoles()
.ToListAsync();
List<Lib.Dtos.AllUserInRolesDto> usersListDto = usersList
.Select( u => ToDto( u ) )
.ToList();
return new JsonResult( usersListDto );
}
// Entity-to-DTO mapping functions (if you have a lot of DTOs and entities, consider using AutoMapper to reduce the tedium)
private static AllUserInRolesDto ToDto( User user )
{
return new AllUserInRolesDto()
{
FullName = user.FullName,
Email = user.Email,
Roles = user.Roles.Select( r => ToDto( r ) ).ToList()
};
}
private static RoleDto ToDto( Role role )
{
return new RoleDto()
{
RoleName = role.RoleName
};
}
I have a project where I'm using CosmosDb (SQL API) as my database. It's a .Net Core project and I'm using the latest stable NuGet packages.
The document client is created as follows and use a custom contract resolver.
new DocumentClient(new Uri(settings.DatabaseUri), settings.DatabaseKey,
new JsonSerializerSettings
{
ContractResolver = new PrivateSetterCamelCasePropertyNamesContractResolver(),
Converters = new List<JsonConverter>
{
new EmailJsonConverter()
}
});
I have a collection called EmailAccount
public class EmailAccount : Entity
{
public string Email { get; private set; }
public string DisplayName { get; private set; }
public EmailAccount(DDD.Core.ValueObjects.Email email,
string displayName)
{
Email = email ?? throw new ArgumentNullException(nameof(email));
DisplayName = string.IsNullOrWhiteSpace(displayName) ? throw new ArgumentNullException(nameof(displayName)) : displayName;
}
}
All the properties are converted into camel-case when serialized which all works fine. But the problem is when I try to filter the documents. The SQL query that's generated looks something like this when I try to filter by the Email.
SELECT * FROM root WHERE (root["Email"] = "amila#iagto.com")
The problem is with the case of the property (Email). The property in the database is email but the query generator doesn't seem to be adhering to the ContractResolver provided and generates the above sql query which doesn't return any result.
If I put [JsonProperty("email")] above the Email property, the query is generated properly. Anyway to get the query generated properly without using attributes in the Entity class?
Any help much appreciated.
You need to set the JsonSerializerSettings at the CreateDocumentQuery level for the LINQ to SQL to pick it up.
This property was added in the SDK on 2.0.0+ versions.
I have a method that does some work in a transaction:
public async Task<int> AddAsync(Item item)
{
int result;
using (var transaction = await _context.Database.BeginTransactionAsync())
{
_context.Add(item);
// Save the item so it has an ItemId
result = await _context.SaveChangesAsync();
// perform some actions using that new item's ItemId
_otherRepository.Execute(item.ItemId);
transaction.Commit();
}
return result;
}
I'd like to add unit tests to check that if _context.SaveChangesAsync or _otherRepository.Execute fail then the transaction is rolled back, is that possible?
I can't see a way to do that using InMemory or SQLite?
#Ilya Chumakov's excellent answer allowed me to unit test for the transaction. Our discussion in the comments then exposed some interesting points that I thought were worth moving into an answer so they'd be more permanent and easier to see:
The primary point is that the events logged by Entity Framework change dependent on the database provider, which surprised me. If using the InMemory provider you get just one event:
Id:1; ExecutedCommand
Whereas if you use Sqlite for the in-memory database you get four events:
Id:1; ExecutedCommand
Id:5; BeginningTransaction
Id:1; ExecutedCommand
Id:6; CommittingTransaction
I hadn't expected the events logged to change depending on the DB provider.
To anyone wanting to look into this more, I captured the event details by changing Ilya's logging code as follows:
public class FakeLogger : ILogger
{
public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception,
Func<TState, Exception, string> formatter)
{
var record = new LogRecord
{
EventId = eventId.Id,
RelationalEventId = (RelationalEventId) eventId.Id,
Description = formatter(state, exception)
};
Events.Add(record);
}
public List<LogRecord> Events { get; set; } = new List<LogRecord>();
public bool IsEnabled(LogLevel logLevel) => true;
public IDisposable BeginScope<TState>(TState state) => null;
}
public class LogRecord
{
public EventId EventId { get; set; }
public RelationalEventId RelationalEventId { get; set; }
public string Description { get; set; }
}
And then I adjusted my code that returns an in-memory database so that I could switch in-memory DB provider as follows:
public class InMemoryDatabase
{
public FakeLogger EfLogger { get; private set; }
public MyDbContext GetContextWithData(bool useSqlite = false)
{
EfLogger = new FakeLogger();
var factoryMock = Substitute.For<ILoggerFactory>();
factoryMock.CreateLogger(Arg.Any<string>()).Returns(EfLogger);
DbContextOptions<MyDbContext> options;
if (useSqlite)
{
// In-memory database only exists while the connection is open
var connection = new SqliteConnection("DataSource=:memory:");
connection.Open();
options = new DbContextOptionsBuilder<MyDbContext>()
.UseSqlite(connection)
.UseLoggerFactory(factoryMock)
.Options;
}
else
{
options = new DbContextOptionsBuilder<MyDbContext>()
.UseInMemoryDatabase(Guid.NewGuid().ToString())
// don't raise the error warning us that the in memory db doesn't support transactions
.ConfigureWarnings(x => x.Ignore(InMemoryEventId.TransactionIgnoredWarning))
.UseLoggerFactory(factoryMock)
.Options;
}
var ctx = new MyDbContext(options);
if (useSqlite)
{
ctx.Database.EnsureCreated();
}
// code to populate the context with test data
ctx.SaveChanges();
return ctx;
}
}
Finally, in my unit test I made sure to clear the event log just before the assert part of my test to ensure I don't get a false positive due to events that were logged during the arrange part of my test:
public async Task Commits_transaction()
{
using (var context = _inMemoryDatabase.GetContextWithData(useSqlite: true))
{
// Arrange
// code to set up date for test
// make sure none of our setup added the event we are testing for
_inMemoryDatabase.EfLogger.Events.Clear();
// Act
// Call the method that has the transaction;
// Assert
var result = _inMemoryDatabase.EfLogger.Events
.Any(x => x.EventId.Id == (int) RelationalEventId.CommittingTransaction);
You could check EF Core logs for a RelationalEventId.RollingbackTransaction event type. I provided full details here:
How to trace an Entity Framework Core event for integration testing?
How it could look:
Assert.True(eventList.Contains((int)RelationalEventId.CommittingTransaction));
I think you are asking about how to rollback when a commit fails, EF core will auto rollback on if any of the statement failed
Read more here
, if you are asking for other reason or you want to do something when rollback happens, just to add try catch blocks,
using (var transaction = await
_context.Database.BeginTransactionAsync()){
try {
_context.Add(item);
// Save the item so it has an ItemId
result = await _context.SaveChangesAsync();
// perform some actions using that new item's ItemId
_otherRepository.Execute(item.ItemId);
transaction.Commit();
}
catch (Exception)
{
// failed, Do something
} }
I have DropDownList displays all server present in my network
I want to populate the databse names when i changed it into another dropdown
I want a LINQ query to get this.
See the question here on how to get the list of databases available to the logged-in user:
SELECT name
FROM sys.sysdatabases
WHERE HAS_DBACCESS(name) = 1
Implementing this into LINQ requires you to publish the sysdatabases view into your own view. I would recommend creating a view for the job in one of the databases:
CREATE VIEW [dbo].[vewDatabases]
AS
SELECT name
FROM sys.sysdatabases
WHERE HAS_DBACCESS(name) = 1
GO
Add this to your LINQ data model, and you will be able to select from it like so [c#]:
var databaseNames = serverDataContext.vewDatabases.Select(a => a.name);
You can then populate the DropDownList with the contents of databaseNames.
I don't think this is a job for Linq2SQL (though I'm not overly familiar with it).
Basically, I think you can get the results you want by looking at one of the SYS_ tables, or a SP_ stored procedure. Can't remember which - been a while since I did anything with SQL Server.
Try code below:
protected void ddList_SelectedIndexChanged(object sender, EventArgs e)
{
PopulateDatabaseDropDown(ddList.SelectedItem.Text);
}
private void PopulateDatabaseDropDown(string server)
{
ddDatabase.DataSource = DatabaseName(server);
ddDatabase.DataValueField = "DatabaseId";
ddDatabase.DataTextField = "Name";
ddDatabase.DataBind();
}
private DataBase[] DatabaseName(string serverName)
{
List<DataBase> data = new List<DataBase>();
System.Data.Linq.DataContext db = new System.Data.Linq.DataContext("Data Source="+serverName+";Initial Catalog=master;Integrated Security=SSPI");
var dbName = db.ExecuteQuery<DataBase>("select database_id, [name] from sys.databases").AsEnumerable();
foreach (var item in dbName)
data.Add(new DataBase() { DatabaseId = item.DatabaseId, Name = item.Name });
return data.ToArray();
}
}
public class DataBase
{
public string Name { get; set; }
public int DatabaseId { get; set; }
}