I am still new to C# and I am struggling to find a solution to my problem. My SQL dapper query returns a table (based on my understanding though it is not really a table if it is IEnumerable unlike what I am use to working with ADO and recordsets) with three columns col1, col2, and col3 and has multiple rows. I need to loop through this query result for each row and test the values (ie, a foreach loop where I check row(0).field1=5, row(1).field1 = 5 for each row, etc) do what I need to do. This seems so basic but I all the dapper tutorials I see do not show examples for this and if they do they seem to utilize class objects rather than accessing the results directly (if thats even possible or do you have to map the results to a model?) My code is as follows:
String query = "exec dbo.storeProcedure #jsonData, #mainDocJSON, #supportingDocsJSON";
IEnumerable queryResult;
using (var connection = new SqlConnection(connectionString))
{
queryResult = connection.Query(query, new { jsonData = jsonData, mainDocJSON = mainDocJSON, supportingDocsJSON = supportingDocsJSON });
}
I also end up returning IEnumerable results from the controller this code resides in so I send it back to the user in JSON using the following.
return Ok(queryResult);
connection.Query return a IEnumerable, why dont we create a class to map the set from ? Dapper is a micro-ORM, but still... ORM.
For ex: Your table return 3 column Id, Name, CreatedDate.
// declare a class to map the result first
public class ResultHolderDto
{
public int Id { get; set; }
public string Name { get; set; }
public DateTime CreatedDate { get; set; }
}
// query somewhere
// This will return IEnumerable<ResultHolderDto>, feel free to play around as normal
var queryResult = await connection.QueryAsync<ResultHolderDto>(query, new { jsonData = jsonData, mainDocJSON = mainDocJSON, supportingDocsJSON = supportingDocsJSON });
foreach(var item in queryResult)
{
var col1Value = queryResult.Id;
var col2Value = queryResult.Name;
var col3Value = queryResult.CreatedDate;
// Then do something with col1Value, col2Value, col3Value...
}
I have 2 lists of IDs and I need to return a list with the products that aren't in any of those lists:
public IEnumerable<Produto> GetProdutosIdNotInFamily(Guid produtoId)
{
var produtosPai = GetListaPaisId(produtoId);
var produtosFilho = GetListaFilhosId(produtoId);
var prod = _dbContext.Produtos
.Where(u => !produtosPai.Any(p => p.ProdutoFilhoId == u.Id)
&& !produtosFilho.Any(p => p.ProdutoFilhoId == u.Id));
return prod;
}
You can do this in two ways -- One using Contains and other using Any like you provided in your snippet in the post.
Using Contains Method
If you want to use Contains() method, you may be pulling out all the product Ids into a collection and apply LINQ on top of it and get the list that is not part of both your reference lists. Sample code is as shown below
// This is the sample model I am dealing with
public class Dummy
{
public int Id { get; set; }
public string Name { get; set; }
}
// Assuming the below call returns list of 'Dummy' objects
var products = _dbContext.Produtos;
// list1 & list2 are populated in your case already through the method calls
var exclusionList1 = list1.Select(x => x.Id).ToList<int>();
var exclusionList2 = list2.Select(x => x.Id).ToList<int>();
var myList = products.Where(x => !exclusionList1.Contains(x.Id) && !exclusionList1.Contains(x.Id)).ToList();
Contains is an instance method and takes an object as a parameter and the time complexity depends on the collection you're using this on.
Using Any
Just like Where, Any is an extension method. It takes a delegate as a parameter which gives you greater flexibility and control with respect to what you would want to do.
Applying Any to your scenario is as shown below:
var products = _dbContext.Produtos;
var exclusionList1 = GetListaPaisId(produtoId);
var exclusionList2 = GetListaFilhosId(produtoId);
var prod = _dbContext.Produtos.Where(x => !exclusionList1.Any(z => x.Id == z.Id) &&
!exclusionList2.Any(z => x.Id == z.Id)).ToList();
You can choose your approach based on the context under which you are performing this operation.
public ActionResult Rajasthan()
{
//List<PackageGallery> all = new List<PackageGallery>();
using (travelAndTourismEntities objentity = new travelAndTourismEntities())
{
List<PackageGallery> all = (from p in objentity.PackageGalleries where p.ParentCategory == "Rajasthan" orderby p.Imageid select p).ToList();
// all = objentity.PackageGalleries.ToList();
return View(all);
}
}
I am writing this query but this is specific to rajasthan only how to make it generalize
You can create a parameter to your action method where you accept the state name you want to use in your filter.
public ActionResult PackageGalleries(string id)
{
var all = new List<PackageGallery>();
using (var db = new travelAndTourismEntities())
{
all = db.PackageGalleries
.Where(s=>s.ParentCategory==id)
.OrderBy(x=>x.ImageId).ToList();
}
return View(all);
}
And you can call it like yourSiteName/yourControllerName/PackageGalleries/rajasthan or yourSiteName/yourControllerName/PackageGalleries/kerala
The last part of the url will be mapped to the id parameter of the action method.
Question
I'm trying to use the Dynamic Linq Sample from Microsoft with BindingList<T> objects. But it looks like the Dynamic Linq will only work with IQueryable. What's the deal here, why doesn't BindingList<T> implement IQueryable. And is there a way around this?
Background Detail: I have many data sets that I need to dynamically filter at run time. Here is an example:
BindingList<MyObject> list = new BindingList<MyObject>();
MyObject selectedObj = list.FirstOrDefault(o => o.Name == "Master P")
// then later ...
MyObject selectedObj = list.FirstOrDefault(o => o.City == "Boston")
I am trying to make these queries dynamic, so the user can choose from all properties of MyObject to use in the query.
There is an Extension method on BindingList; AsQueryable(). So you can use
list.AsQueryable();
But if you want to search on all criteria could you create a search that uses an instance of MyObject as the search criteria and then generated a result set based on the Criteria in the object using standard link.
For example:
public List<MyObject> Search(MyObject SearchCriteria)
{
BindingList<MyObject> list = new BindingList<MyObject>();
list.Add(new MyObject("Test", "Boston"));
list.Add(new MyObject("Test2", "Atlanta"));
IEnumerable<MyObject> results = list.AsEnumerable();
if (!String.IsNullOrEmpty(SearchCriteria.Name))
results = results.Where(l => l.Name.Contains(SearchCriteria.Name));
if (!String.IsNullOrEmpty(SearchCriteria.City))
results = results.Where(l => l.City.Contains(SearchCriteria.City));
return results.ToList();
}
So in the following, Results1 will have 2 results and Results 2 will have only 1.
List<MyObject> results1 = Search(new MyObject("Test", ""));
List<MyObject> results2 = Search(new MyObject("Test", "Boston"));
I used a simple structure for MyObject as an example in this:
public class MyObject
{
public MyObject(string name, string city)
{
this.Name = name;
this.City = city;
}
public string Name { get; set; }
public string City { get; set; }
}
given a query in the form of an ICriteria object, I would like to use NHibernate (by means of a projection?) to find an element's order,
in a manner equivalent to using
SELECT ROW_NUMBER() OVER (...)
to find a specific item's index in the query.
(I need this for a "jump to page" functionality in paging)
any suggestions?
NOTE: I don't want to go to a page given it's number yet - I know how to do that - I want to get the item's INDEX so I can divide it by page size and get the page index.
After looking at the sources for NHibernate, I'm fairly sure that there exists no such functionality.
I wouldn't mind, however, for someone to prove me wrong.
In my specific setting, I did solve this problem by writing a method that takes a couple of lambdas (representing the key column, and an optional column to filter by - all properties of a specific domain entity). This method then builds the sql and calls session.CreateSQLQuery(...).UniqueResult(); I'm not claiming that this is a general purpose solution.
To avoid the use of magic strings, I borrowed a copy of PropertyHelper<T> from this answer.
Here's the code:
public abstract class RepositoryBase<T> where T : DomainEntityBase
{
public long GetIndexOf<TUnique, TWhere>(T entity, Expression<Func<T, TUnique>> uniqueSelector, Expression<Func<T, TWhere>> whereSelector, TWhere whereValue) where TWhere : DomainEntityBase
{
if (entity == null || entity.Id == Guid.Empty)
{
return -1;
}
var entityType = typeof(T).Name;
var keyField = PropertyHelper<T>.GetProperty(uniqueSelector).Name;
var keyValue = uniqueSelector.Compile()(entity);
var innerWhere = string.Empty;
if (whereSelector != null)
{
// Builds a column name that adheres to our naming conventions!
var filterField = PropertyHelper<T>.GetProperty(whereSelector).Name + "Id";
if (whereValue == null)
{
innerWhere = string.Format(" where [{0}] is null", filterField);
}
else
{
innerWhere = string.Format(" where [{0}] = :filterValue", filterField);
}
}
var innerQuery = string.Format("(select [{0}], row_number() over (order by {0}) as RowNum from [{1}]{2}) X", keyField, entityType, innerWhere);
var outerQuery = string.Format("select RowNum from {0} where {1} = :keyValue", innerQuery, keyField);
var query = _session
.CreateSQLQuery(outerQuery)
.SetParameter("keyValue", keyValue);
if (whereValue != null)
{
query = query.SetParameter("filterValue", whereValue.Id);
}
var sqlRowNumber = query.UniqueResult<long>();
// The row_number() function is one-based. Our index should be zero-based.
sqlRowNumber -= 1;
return sqlRowNumber;
}
public long GetIndexOf<TUnique>(T entity, Expression<Func<T, TUnique>> uniqueSelector)
{
return GetIndexOf(entity, uniqueSelector, null, (DomainEntityBase)null);
}
public long GetIndexOf<TUnique, TWhere>(T entity, Expression<Func<T, TUnique>> uniqueSelector, Expression<Func<T, TWhere>> whereSelector) where TWhere : DomainEntityBase
{
return GetIndexOf(entity, uniqueSelector, whereSelector, whereSelector.Compile()(entity));
}
}
public abstract class DomainEntityBase
{
public virtual Guid Id { get; protected set; }
}
And you use it like so:
...
public class Book : DomainEntityBase
{
public virtual string Title { get; set; }
public virtual Category Category { get; set; }
...
}
public class Category : DomainEntityBase { ... }
public class BookRepository : RepositoryBase<Book> { ... }
...
var repository = new BookRepository();
var book = ... a persisted book ...
// Get the index of the book, sorted by title.
var index = repository.GetIndexOf(book, b => b.Title);
// Get the index of the book, sorted by title and filtered by that book's category.
var indexInCategory = repository.GetIndexOf(book, b => b.Title, b => b.Category);
As I said, this works for me. I'll definitely tweak it as I move forward. YMMV.
Now, if the OP has solved this himself, then I would love to see his solution! :-)
ICriteria has this 2 functions:
SetFirstResult()
and
SetMaxResults()
which transform your SQL statement into using ROW_NUMBER (in sql server) or limit in MySql.
So if you want 25 records on the third page you could use:
.SetFirstResult(2*25)
.SetMaxResults(25)
After trying to find an NHibernate based solution for this myself, I ultimately just added a column to the view I happened to be using:
CREATE VIEW vw_paged AS
SELECT ROW_NUMBER() OVER (ORDER BY Id) AS [Row], p.column1, p.column2
FROM paged_table p
This doesn't really help if you need complex sorting options, but it does work for simple cases.
A Criteria query, of course, would look something like this:
public static IList<Paged> GetRange(string search, int rows)
{
var match = DbSession.Current.CreateCriteria<Job>()
.Add(Restrictions.Like("Id", search + '%'))
.AddOrder(Order.Asc("Id"))
.SetMaxResults(1)
.UniqueResult<Paged>();
if (match == null)
return new List<Paged>();
if (rows == 1)
return new List<Paged> {match};
return DbSession.Current.CreateCriteria<Paged>()
.Add(Restrictions.Like("Id", search + '%'))
.Add(Restrictions.Ge("Row", match.Row))
.AddOrder(Order.Asc("Id"))
.SetMaxResults(rows)
.List<Paged>();
}