I have a problem using QBE with NHibernate.
Here's a sample code:
Person person = new Person();
person.FirstName = "e";
using (ISession session = SessionFactory.CreateSession())
{
Example example = Example.Create(person).ExcludeProperty("DateOfBirth").EnableLike().IgnoreCase();
IList<Person> people = session.CreateCriteria<Person>().Add(example).List<Person>();
return people;
}
What I expect is that this example & criteria will return all persons whose first name starts with an "e". BUT, to accomplish this I had to insert escape character in the example object's property. Like this:
person.FirstName = "e%";
With this modification, query returns the desired results.
Shouldn't the "EnableLike" take care of this?
What am I doing wrong?
Thanks!
im not an expert, but seems you need to put a matchmode in your enablelike(), just like:
Example.Create(person).ExcludeProperty("DateOfBirth")
.EnableLike(NHibernate.Expression.MatchMode.Start)
.IgnoreCase();
the matchmode can be:start, end,exact and anywhere
hope this help
Related
I am working on Database First Approach in Entity Framework where I have to retrieve specific columns from the Entity.
Public IQueryable<Entity.Employees> GetEmployeeName(String FName,String LName)
{
var query = (from s in Employees
where s.firstName = FName && s.lastName = LName
select new {s.firstName, s.middleName});
return query;
}
Here return statement is throwing an error where it seems that its not matching with Employees (entity) columns. Could you please help me in sorting out this issue? Thanks in advance.
You need to use == for comparison, also you need to use dynamic type as return type since you are returning a custom anonymous type. Try this
Public IQueryable<dynamic> GetEmployeeName(String FName,String LName)
{
var query=(from s in Employees
where s.firstName==FName && s.lastName==LName
select new {s.firstName,s.middleName});
return query.AsQueryable();
}
Finally you will use it like below, keep in mind that intelisense won't work on dynamic object.
var query = GetEmployeeName("Jake", "Smith");
List<dynamic> results = query.ToList();
foreach (dynamic result in results)
{
string fristName = result.FirstName;
string lastName = result.MiddleName;
}
I use RedBeanPHP 3.5.1 for ORM in my MVP project (powered by Nette FW).
I need to get ID of the last inserted element, that is owned by element from another table. Below you can find method representing functionality which I just described:
public function createSite($userId, $siteName, $feedUrl, $reloadTime, $reloadRate){
$site = R::dispense('site');
$site->user_id = $userId;
$site->name = $siteName;
$site->feed = $feedUrl;
$site->reload_time = $reloadTime;
$site->reload_rate = $reloadRate;
$user = R::load('user', $userId);
$user->ownSite[] = $site;
$id = R::store($user);
return $id;
}
Now I would assume that line
$id = R::store($user);
would store site ID into $id variable since it is owned by already existing user. Instead of that it fills variable with user ID that I have no further use for.
So my question is: How do I get last inserted ID of owned bean that was just created by calling R::store() method on parent (just loaded) bean? Is there an implementation on this in RedBean or do I have to do this manually?
I browsed every corner of RedBeanPHP project web but so far no luck.
Thanks for possible suggestions, guys.
Using common sense I finally figured out how to solve this elegantly and since no one answered my question so far let my just do that myself.
Since R::store($user) is capable of storing both $user and $site, there is misleadingly no need to store $site object manually.
But if you need to get last inserted id of owned bean, there is really no harm in doing so. By storing $site object framework will do the exact same thing and on top of that it returns resired id.
So the correct method implementation looks like this:
public function createSite($userId, $siteName, $feedUrl, $reloadTime, $reloadRate){
$site = R::dispense('site');
$site->user_id = $userId;
$site->name = $siteName;
$site->feed = $feedUrl;
$site->reload_time = $reloadTime;
$site->reload_rate = $reloadRate;
$user = R::load('user', $userId);
$user->ownSite[] = $site;
$id = R::store($site);
R::store($user);
return $id;
}
So in conclusion, hats off to RedBeanPHP ORM FW and I sincerely hope this helps people with similar problem in the future.
There is a function called R::findLast('...')
$last_record = R::findLast('...');
Not sure if this would have been a correct answer 7 years ago but at least now there is no need to do any kind of extra work:
$shop = R::dispense( 'shop' );
$shop->name = 'Antiques';
$vase = R::dispense( 'product' );
$vase->price = 25;
$shop->ownProductList[] = $vase
R::store( $shop );
echo $vase->$id; // <-- yes, id which was created by database is present here
Am developing a ViewModel/PresentationModel which is getting complex.
I want the Linq query to return an IQueryable<UserPresentationModel>
Using EntityFramework against MSSQL
Is it possible to do any sort of iteration over the set before returning it to the presentation layer ie
List<UserPresentationModel> list = new List<UserPresentationModel>();
foreach (var person in listOfPeople)
{
UserPresentationModel u = new UserPresentationModel();
int userUIStatus = GetColourStateOfPerson(person);
u.FirstName = person.FirstName;
u.UserUIStatus = userUIStatus;
list.Add(u);
}
return list
This feels like it would always be N+1, and I'd never get the advantages of deferred execution, composing of queries..
Or (and I think am answering my own question) do I need to think in a SQL set based manner.
First, we can convert your code to LINQ.
IEnumerable<UserPresentationModel> models =
from person in listOfPeople
select new UserPresentationModel
{
FirstName = person.FirstName,
UserUIStatus = GetColourStateOfPerson(person)
}
return models.ToList();
Now, if GetColourStateOfPerson is making a DB round-trip, you definitely want to pull that out.
IDictionary<int, int> colourStatesByPersonId = GetColourStatesOfPeople(listOfPeople);
IEnumerable<UserPresentationModel> models =
from person in listOfPeople
select new UserPresentationModel
{
FirstName = person.FirstName,
UserUIStatus = colourStatesByPersonId[person.PersonId]
}
return models.ToList();
You could probably manage to create a single LINQ query that grabs just the first names and colour states of the people you want in a single query, but you haven't provided enough information about your data context for me to help you with that.
I would personally avoid passing around an IQueryable, which could continue making database trips any time somebody touches it. Let your data layer get out all the data you're likely to need, compose it into a list, and return that.
use IEnumerable<T>.Aggregate() instead of looping.
return listOfPeople.Aggregate(new List<UserPresentationModel>(), person => {
return new UserPresentationModel {
FirstName = person.FirstName,
UserUIStatus = GetColourStateOfPerson(person)
};
}).AsQueryable();
return listOfPeople.AsEnumerable().Select(p =>
new UserPresentationModel
{
FirstName = p.FirstName,
UserUIStatus = GetColourStateOfPerson(p)
}).AsQueryable();
I'm assuming that listOfPeople is an IQueryable that will eventually execute against your database. If that is the case then AsEnumerable() is important because SQL Server won't know what to do with GetColourStateOfPerson(). AsEnumerable() will force the IQueryable's expression tree to execute, pull the resulting rows out of your database and then apply Select() transformation in code as oppose to in SQL Server.
If you can implement GetColourStateOfPerson() as a stored proc or database function then you can omit AsEnumerable() and AsQueryable() and allow execution to delay even longer.
I have a scenario where I have to update an entity if it exists or add a new one if it doesn't.
I would like to execute a single method for this (it would be great if it were a single trip to the server).
Is there something like that in EF?
Right now my code looks like this:
var entity = db.Entities.FirstOrDefault(e => e.Id == myId);
if (entity == null)
{
entity = db.Entities.CreateObject();
entity.Id = myId;
}
entity.Value = "my modified value";
db.SaveChanges();
But I would like to avoid the first query, something like this:
var entity = new Entity();
entity.Id = myId;
entity.Value = "my modified value";
db.AddOrAttach(entity);
db.SaveChanges();
Is there anything similar? or do I have to perform the first query no matter what?
Thanks
You have to perform the first query no matter what, unfortunately.
One option would be to write a stored procedure that performs a T-SQL MERGE then map it to a function import, though that would require that you pass the scalar values of the entity as parameters (and support for navigation properties would be done), but it would accomplish what you're after.
I ran some quick test code for editing in MVC 3 with EF 4 and it seems to work for edit with following code:
using (var context = new TestStackOverFlowEntities())
{
Person p = new Person();
p.Id = long.Parse(collection["Id"]);
p.FirstName = collection["FirstName"];
p.LastName = collection["LastName"];
context.People.Attach(p);
context.ObjectStateManager.ChangeObjectState(p, System.Data.EntityState.Modified);
context.SaveChanges();
return RedirectToAction("Index");
}
Edit: I checked with creating new object too, you need to change this
context.ObjectStateManager.ChangeObjectState(p, System.Data.EntityState.Added);
when Id == 0 //ie new object.
Quick and dirty code to add new is this:
using (var context = new TestStackOverFlowEntities())
{
Person p = new Person();
p.Id = 0;
p.FirstName = collection["FirstName"];
p.LastName = collection["LastName"];
context.People.Attach(p);
context.ObjectStateManager.ChangeObjectState(p, System.Data.EntityState.Added);
context.SaveChanges();
return RedirectToAction("Index");
}
If you are just trying to limit code to clarify your controllers:
db.Attach(model);
db.SaveChanges(model);
Will update if the Entity Key exists, and create if it does not.
// goal: update Address record identified by "id", with new data in "colVal"
string cstr = ConnectionApi.GetSqlConnectionString("SwDb"); // get connection str
using (DataContext db = new DataContext(cstr)) {
Address addr = (from a in db.GetTable<Address>()
where a.Id == id
select a).Single<Address>();
addr.AddressLine1 = colValue.Trim();
db.SubmitChanges(); // this seems to have no effect!!!
}
In the debugger, addr has all the current values from the db table, and I can verify that AddressLine1 is changed just before I call db.SubmitChanges()... SQL Profiler shows only a "reset connection" when the SubmitChanges line executes. Anyone got a clue why this isn't working? THANKS!
You can get a quick view of the changes to be submitted using the GetChangeSet method.
Also make sure that your table has a primary key defined and that the mapping knows about this primary key. Otherwise you won't be able to perform updates.
Funny, to use GetTable and Single. I would have expected the code to look like this:
string cstr = ConnectionApi.GetSqlConnectionString("SwDb"); // get connection str
using (DataContext db = new DataContext(cstr))
{
Address addr = (from a in db.Address where a.Id == id select a).Single();
addr.AddressLine1 = colValue.Trim();
db.SubmitChanges(); // this seems to have no effect!!!
}
I got no idea what GetTable will do to you.
Another thing, for debugging Linq2SQL try adding
db.Log = Console.Out;
before SubmitChanges(), this will show you the executed SQL.
Thanks -- your comments will help me sort this out I'm sure! I didn't have the "Id" column defined as the PrimaryKey so that's an obvious non-starter. I would have expected that LinqToSQL would have thrown an error when the update fails. -- S.
Ok, here's the result. I can't use the form db.Address, because I didn't use the designer to create my database objects, instead I defined them as classes like this:
[Table(Name = "Addresses")]
public class Address
{
[Column(Name = "Id",IsPrimaryKey=true)]
public int Id { get; set; }
[Column(Name = "AddressLine1")]
public string AddressLine1 { get; set; }
...
Originally, I didn't have the "Id" column set as PK in the database, nor did I have it identified using IsPrimaryKey=true in the [Column...] specifier above. BOTH are required! Once I made that change, the ChangeSet found the update I wanted to do, and did it, but before that it told me that 0 rows needed to be updated and refused to commit the changes.
Thanks for your help! -- S.