I am new in ASP.NET MVC 4. In my project I am using Code First technique in of EF. I want to retrieve some data from database and I used following code for this :
List<SelectListItem> ls = new List<SelectListItem>();
var lm = from m in db.BOs //fetch data from database
select m;
foreach (var temp in lm)
{
ls.Add(new SelectListItem() { Text = temp.Name, Value = temp.Id.ToString() });
}
But when execution pointer move inside foreach it immediately come back out of the loop showing return ls value Count = 0. Code does not giving me any error while running that's why I am not getting where is going wrong.
UPDATE: I found something new this problem. When I kept mouse pointer over var lm; it shows me query and in query table name in FROM clause is not that one in my SQL database. My SQL table name is BO and in query it is taking BOes. I don't know from where this name is coming. So How I overcome this??
decorate your BO class with Table("BO") to specify the table name (attribute is in System.ComponentModel.DataAnnotations.Schema namespace)
[Table("BO")]
public partial class BO
{
...
Write following code inside DbContext class :
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
}
The modelBuilder.Conventions.Remove statement in the OnModelCreating method prevents table names from being pluralized. If you didn't do this, the generated tables would be named Students, Courses, and Enrollments. Instead, the table names will be Student, Course, and Enrollment. Developers disagree about whether table names should be pluralized or not. This tutorial uses the singular form, but the important point is that you can select whichever form you prefer by including or omitting this line of code.
Related
I'm trying to use RepoDb to query the contents of a table (in an existing Sql Server database), but all my attempts result in an InvalidOperationException (There are no 'contructor parameter' and/or 'property member' bindings found between the resultset of the data reader and the type 'MyType').
The query I'm using looks like the following:
public Task<ICollection<MyType>> GetAllAsync()
{
var result = new List<MyType>();
using (var db = new SqlConnection(connectionString).EnsureOpen())
{
result = (await db.ExecuteQueryAsync<MyType>("select * from mytype")).ToList();
}
return result;
}
I'm trying to run this via a unit test, similar to the following:
[Test]
public async Task MyTypeFetcher_returns_all()
{
SqlServerBootstrap.Initialize();
var sut = new MyTypeFetcher("connection string");
var actual = await sut.GetAllAsync();
Assert.IsNotNull(actual);
}
The Entity I'm trying to map to matches the database table (i.e. class name and table name are the same, property names and table column names also match).
I've also tried:
putting annotations on the class I am trying to map to (both at the class level and the property level)
using the ClassMapper to map the class to the db table
using the FluentMapper to map the entire class (i.e. entity-table, all columns, identity, primary)
putting all mappings into a static class which holds all mapping and configuration and calling that in the test
providing mapping information directly in the test via both ClassMapper and FluentMapper
From the error message it seems like RepoDb cannot find the mappings I'm providing. Unfortunately I have no idea how to go about fixing this. I've been through the documentation and the sample tutorials, but I haven't been able to find anything of use. Most of them don't seem to need any mapping configuration (similar to what you would expect when using Dapper). What am I missing, and how can I fix this?
So I've created an HTML table on a Razor page as shown below. Basically I'm just calling a method that returns a list and then using a foreach to go create the rows and controls. The part I'm completely lost on is how I go about posting this data back to the server and on the code behind using that data to insert back to SQL Server. I'm using Dapper and I'd like each row of the table to represent a data row, or one object, but how do I get the data from the Razor page passed back as a list of a class? Not sure if my terminology is accurate here but can you model bind on a list of a type? Would appreciate some assistance thanks!
It seems I'm so far off track (or so few people use asp.net core and Dapper) that I'm not getting any help. But someone very helpful marked down my question without commenting - thanks so much.
I realised the key thing I was doing wrong was trying to circumvent model binding, so I created a class/type Rating that represents each row (each column as a property) and then an Assessment type/class that contains a List as one of the properties.
On the Razor page:
#foreach (Comp c in Model.GetComps())
{
count++;
Model.assessment.Ratings.Add(new Rating());
Model.assessment.Ratings[count].AchievedCompetencyID = c.AchievedCompetencyID;
Code behind:
public void OnPost()
{
using (IDbConnection con = new SqlConnection(Startup.conStr))
{
long assessID = con.Insert(assessment);
foreach (Rating r in assessment.Ratings)
{
r.AssessmentID = Convert.ToInt32(assessID);
con.Insert(r);
}
}
}
I am having a below csv file:
Employer EID,File Creation Date,File Creation Time,Salary Year and Month,Total Salaries,Total Records,,,
1006200,20032016,1031,201603,2200,1,,,
Record ID,Employee QID,Number of Working Days,Net Salary,Basic Salary,Extra hours,Extra Income,Deductions,Payment Type
1,29135617946,31,2200,2200,0,0,0,SALARY
2,29135617947,31,2200,2300,0,0,0,SALARY
3,29135617948,31,2200,2250,0,0,0,SALARY
Above file is having the first part as the employer information and the seond set of rows having the employees working with that along with their salary.
I want to create a complex class Employer which will be having the employees attributes along with a List of complex type named Employee that will include all the employees information.
Please help me by giving a direction/code to how can I achieve this using the FileHelpers.
You can use a MasterDetailEngine. There is an example in the documentation.
You provide a selector class to enable FileHelpers to determine whether a record is a master record or a detail record.
private RecordAction ExampleSelector(string record)
{
if (record.Length < 2)
return RecordAction.Skip;
if (IsMasterRecord(record)) // some way of identifying your master records
return RecordAction.Master;
else
return RecordAction.Detail;
}
Then you can read your the file into your classes like this:
var engine = new MasterDetailEngine<Employer, Employee>(new MasterDetailSelector(ExampleSelector));
var result = engine.ReadFile("Input.txt");
foreach (var group in result) {
Console.WriteLine("Customer: {0}", group.Master.EmployerEid);
foreach (var detail in group.Details)
Console.WriteLine(" Freight: {0}", detail.EmployeeQid);
}
I'm working with Fluent nHibernate on a legacy database and have a main Person table and several extension tables containing additional information about the person. These extension tables are one-to-one, meaning that a person will only have one row on the extension table and the extension table should always map back to one person.
Table: Person
Columns: PersonID, FirstName, LastName, etc.
Table: PersonLogin
Columns: PersonID (FK, unique), UserName, Password, etc.
I have my mappings defined as this (with the irrelevant properties omitted):
public PersonMap()
{
Table("Person");
Id(x => x.Id, "PersonID").Not.Nullable();
References(x => x.Login, "PersonID").LazyLoad();
}
public LoginMap()
{
Table("PersonLogin");
Id(x => x.Id, "PersonID").GeneratedBy.Foreign("Person");
References(x => x.Person, "PersonID").LazyLoad();
}
This works when I have data on both tables, but I recently learned that some of the extension tables don't have data for all Person rows. This caused me to get errors during the query. So, I added .NotFound.Ignore() to my PersonMap making it look like this:
References(x => x.Login, "PersonID").LazyLoad().NotFound.Ignore();
That caused me to get unnecessary selects from the Login table due to https://nhibernate.jira.com/browse/NH-1001 when my business layer doesn't need to project any of the extension table values. It is causing the performance to be terrible in some of my search queries.
I've scoured a lot of posts, but haven't found a rock solid answer about how to address this scenario. Below are the options I've tried:
Option One:
Create rows on the extension table to ensure there is no Person without a row on the extension table and then remove the .NotFound.Ignore().
The issue with this option is that it's a legacy database and I'm not sure where I'd need to update to ensure that a PersonLogin is inserted when a Person is inserted.
Option Two:
Remove the PersonLogin reference from my PersonMap and custom load it inside my Person class. Like this:
public class Person
{
/// <summary> Gets or sets the PersonID </summary>
public virtual int Id { get; set; }
private bool loadedLogin;
private PersonLogin login;
public virtual PersonLogin Login
{
get
{
if (!loadedLogin)
{
login = SessionManager.Session().Get<PersonLogin>(Id);
loadedLogin = true;
}
return login;
}
set
{
login = value;
loadedLogin = true;
}
}
}
The issue I'm having with it is that I can't eagerly fetch the data when performing a query to pull back a large number of Person objects and their Logins.
Option Three:
I just started playing to see if I could write a custom IEntityNotFoundDelegate to not throw the exception for these objects.
private class CustomEntityNotFoundDelegate : IEntityNotFoundDelegate
{
public void HandleEntityNotFound(string entityName, object id)
{
if (entityName == "my.namespace.PersonLogin")
{
return;
}
else
{
throw new ObjectNotFoundException(id, entityName);
}
}
}
And I added this to the config
cfg.EntityNotFoundDelegate = new CustomEntityNotFoundDelegate();
It catches my scenario and returns back now instead of throwing the error, but now when I try to project those PersonLogin properties onto my business objects, it's attempting to use the Proxy object and throws this error that I'm trying to figure out if I can handle cleanly (possibly in a IPostLoadEventListener).
System.Reflection.TargetException occurred
Message = Non-static method requires a target
I think I've got this working now by keeping the .NotFound.Ignore().
I originally stated:
That caused me to get unnecessary selects from the Login table due to https://nhibernate.jira.com/browse/NH-1001 when my business layer doesn't need to project any of the extension table values. It is causing the performance to be terrible in some of my search queries.
I was able to tweak my LINQ queries to use the IQueryOver in some instances and to improve my use of LINQ in other scenarios to project only the necessary values. This appears to have resolved the queries from pulling back the extension tables since their values were not needed in the projections.
I thought that my queries weren't projecting these extension tables, but figured out that I had a method ToKeyValuePair that I was using in the projection to concatenate the ID and a Name field together of some related properties. That method was causing the objects to load completely since LINQ wasn't able to determine that the needed fields were present without joining to the extension table.
I'm using the MVC 4 template with VS 2012. I have enabled a comments section which stores the logged in user's UserId to a table. When I display the comments I want to display the user's user name and email from the UserProfiles table.
I've tried the following code:
public static string GetUserName(int userId)
{
using (var db = new UsersContext())
{
return db.UserProfiles.Single(x => x.UserId == userId).UserName;
}
}
But I get an exception:
The model backing the 'UsersContext' context has changed since the database was created. Consider using Code First Migrations to update the database (http://go.microsoft.com/fwlink/?LinkId=238269).
Any suggestions?
The exception is pretty descriptive. Your model does not reflect what your database look like. I recommend you to read this about code first migrations, basically what migrations mean is that you update your database to match your models, its done with one line of command in VS.
Hope this helps
Also I would recommend you to use .Find() or .First() instead of .Single()