I am trying to load a sortable jqgrid 3.5 from a query with multiple joins in it and having much difficulty as I am a novice with both Linq and jqgrid. In order to allow for sorting I first was attempting to load it using dynamic SQL.
Since I am pulling columns from multiple tables I assume my return will be a class object which I will populate (or will it be a table). How can I return a IQueryable custom class object when using dynamic SQL with multiple .JOIN clauses. If this is impossible how do I return IQueryable data from a stored procedure call. It is easy to create dynamic SQL in the stored procedure - I am unsure how to load my grid with it however.
Sorry if this is all over the place but I can't seem to find a way. If you can recommend the most straight forward way to load my sortable grid from a query which has multiple joins in I am much appreciated.
My controller code:
public ActionResult GridData(string sidx, string sord, int page, int rows)
{
EquipTrak eqt = new EquipTrak();
var equipment = eqt.GetGridEquipment(sidx, sord);
var dataJson = new
{
total = 10000,
page = 1,
records = 10000,
rows = (from e in equipment
select new
{
equip_id = e.equip_id,
cell = new string[] {
e.equip_id,
e.equipType,
e.makeType,
String.Format("{0:MM/dd/yyyy}", e.serv_due_dt)
}
}).ToArray()
};
return Json(dataJson);
}
}
my class code (incomplete):
namespace ULS_Site.Models
{
public class EquipTrak
{
uls_dbDataContext ulsDB = new uls_dbDataContext();
public IQueryable<equipmentCls> GetGridEquipment(string sidx, string sord)
{
try
{
return
Not sure if this is the best or worst solution but I used SQL Server views to handle all the joining required. I could then use .Orderby and .Where against the view which was in my data context.
Related
I am using Apache Ignite as the back-end data store in a SpringBoot Application.
I have a requirement where I need to get all the entities whose name matches one of the names from a set of names.
Hence i am trying to get it implemented using a #Query configuration and a method named findAllByName(Iterable<String> names)as below:
Here on the Query, I am trying to use the 'IN' clause and want to pass an array of names as an input to the 'IN' clause.
#RepositoryConfig(cacheName = "Category")
public interface CategoryRepository extends IgniteRepository<Category, Long>
{
List<Category> findByName(String name);
#Query("SELECT * FROM Category WHERE name IN ( ? )")
Iterable<Category> findAllByName(Iterable<String> names); // this method always returns empty list .
}
In this the method findAllByName always returns empty list, even when ignite has Categories for which the name field matches the data passed in the query.
I am unable to figure out if there is a problem with the Syntax or the query of the method signature or the parameters.
Please try using String[] names instead for supplying parameters.
UPDATE: I have just checked the source, and we don't have tests for such scenario. It means that you're on uncharted territory even if it is somehow possible to get to work.
Otherwise looks unsupported currently.
I know your question is more specific to Spring Data Ignite feature. However, as an alternate, you can achieve it using the SqlQuery abstraction of Ignite.
You will form your query like this. I have pasted the sample below with custom sql function inSet that you will write. Also, the below tells how this is used in your sql.
IgniteCache<String, MyRecord> cache = this.ignite
.cache(this.environment.getProperty(Cache.CACHE_NAME));
String sql = "from “my-ignite-cache”.MyRecord WHERE
MyRecord.city=? AND inSet(?, MyRecord.flight)"
SqlQuery<String, MyRecord> sqlQuery = new SqlQuery<>(MyRecord.class,
sql);
sqlQuery.setArgs(MyCity, [Flight1, Flight2 ] );
QueryCursor<Entry<String, MyRecord>> resultCursor = cache.query(sqlQuery);
You can iterate the result cursor to do something meaningful from the extracted data.
resultCursor.forEach(e -> {
MyRecord record = e.getValue();
// do something with result
});
Below is the Ignite Custom Sql function which is used in the above Query - this will help in replicating the IN clause feature.
#QuerySqlFunction
public static boolean inSet(List<String> filterParamArgIds, String id) {
return filterParamArgIds.contains(id);
}
And finally, as a reference MyRecord referred above can be defined something like this.
public class MyRecord implements Serializable {
#QuerySqlField(name = "city", index = true)
private String city;
#QuerySqlField(name = "flight", index = true)
private String flight;
}
I imagine this is very simple to solve, but i cant seem to figure it out and searching has not resulted anything meaningful.
Business Problem: Just trying to retrieve details from a ADO.NET Entity Data table by passing in a variable to the query. Whats odd is that when I pass in a symbol take "FB" for vSymbol it works fine, however, when passing a variable, it returns the page with no data. This is what its passing into the controller.
View
#Html.ActionLink(item.Symbol, "CompanyDetails", "Companies", new { id = item.Symbol }, null)
Controller
public ActionResult CompanyDetails(string vSymbol)
{
var SymbolDetails = from t in db.Companies
where t.Symbol == vSymbol
select t;
return View(SymbolDetails);
}
I have a field in my database with duplicates. I want to use it in a dropdown list, which has to return distinct data.
Here is the method that I created to do this:
public IEnumerable<SelectListItem> GetBranches(string username)
{
using (var objData = new BranchEntities())
{
IEnumerable<SelectListItem> objdataresult = objData.ABC_USER.Select(c => new SelectListItem
{
Value = c.BRANCH_CODE.ToString(),
Text = c.BRANCH_CODE
}).Distinct(new Reuseablecomp.SelectListItemComparer());
return objdataresult;
}
}
Here is the class I am using:
public static class Reuseablecomp
{
public class SelectListItemComparer : IEqualityComparer<SelectListItem>
{
public bool Equals(SelectListItem x, SelectListItem y)
{
return x.Text == y.Text && x.Value == y.Value;
}
public int GetHashCode(SelectListItem item)
{
int hashText = item.Text == null ? 0 : item.Text.GetHashCode();
int hashValue = item.Value == null ? 0 : item.Value.GetHashCode();
return hashText ^ hashValue;
}
}
}
Nothing is returned and I get the error below. When I try a basic query without Distinct, everything works fine.
{"The operation cannot be completed because the DbContext has been disposed."}
System.Exception {System.InvalidOperationException}
Inner exception = null
How can I return distinct data for my dropdown?
Technically, your problem can be solved simply by appending .ToList() after your Distinct(...) call. The problem is that queries are evaluated JIT (just in time). In other words, until the actual data the query represents is needed, the query is not actually sent to the database. Calling ToList is one such thing that requires the actual data, and therefore will cause the query to be evaluated immediately.
However, the root cause of your problem is that you are doing this within a using statement. When the method exits, the query has not yet been evaluated, but you have now disposed of your context. Therefore, when it comes time to actually evaluate that query, there's no context to do it with and you get that exception. You should really never use a database context in conjuction with using. It's just a recipe for disaster. Your context should ideally be request-scoped and you should use dependency injection to feed it to whatever objects or methods need it.
Also, for what it's worth, you can simply move your Distinct call to before your Select and you won't need a custom IEqualityComparer any more. For example:
var objdataresult = objData.ABC_USER.Distinct().Select(c => new SelectListItem
{
Value = c.BRANCH_CODE.ToString(),
Text = c.BRANCH_CODE
});
Order of ops does matter here. Calling Distinct first includes it as part of the query to the database, but calling it after, as you're doing, runs it on the in-memory collection, once evaluated. The latter requires, then, custom logic to determine what constitutes distinct items in an IEnumerable<SelectListItem>, which is obviously not necessary for the database query version.
I was wondering if there is any way to intercept and modify the sql generated from linq to Sql before the query is sent off?
Basically, we have a record security layer, that given a query like 'select * from records' it will modify the query to be something like 'select * from records WHERE [somesecurityfilter]'
I am trying to find the best way to intercept and modify the sql before its executed by the linq to sql provider.
Ok, first to directly answer your question (but read on for words of caution ;)), there is a way, albeit a finicky one, to do what you want.
// IQueryable<Customer> L2S query definition, db is DataContext (AdventureWorks)
var cs = from c in db.Customers
select c;
// extract command and append your stuff
DbCommand dbc = db.GetCommand(cs);
dbc.CommandText += " WHERE MiddleName = 'M.'";
// modify command and execute letting data context map it to IEnumerable<T>
var result = db.ExecuteQuery<Customer>(dbc.CommandText, new object[] { });
Now, the caveats.
You have to know which query is generated so you would know how to modify it, this prolongs development.
It falls out of L2S framework and thus creates a possible gaping hole for sustainable development, if anyone modifies a Linq it will hurt.
If your Linq causes parameters (has a where or other extension causing a WHERE section to appear with constants) it complicates things, you'll have to extract and pass those parameters to ExecuteQuery
All in all, possible but very troublesome. That being said you should consider using .Where() extension as Yaakov suggested. If you want to centrally controll security on object level using this approach you can create an extension to handle it for you
static class MySecurityExtensions
{
public static IQueryable<Customer> ApplySecurity(this IQueryable<Customer> source)
{
return source.Where(x => x.MiddleName == "M.");
}
}
//...
// now apply it to any Customer query
var cs = (from c in db.Customers select c).ApplySecurity();
so if you modify ApplySecurity it will automatically be applied to all linq queries on Customer object.
If you want to intercept the SQL generated by L2S and fiddle with that, your best option is to create a wrapper classes for SqlConnection, SqlCommand, DbProviderFactory etc. Give a wrapped instance of SqlConnection to the L2S datacontext constructor overload that takes a db connection. In the wrapped connection you can replace the DbProviderFactory with your own custom DbProviderFactory-derived class that returns wrapped versions of SqlCommand etc.
E.g.:
//sample wrapped SqlConnection:
public class MySqlConnectionWrapper : SqlConnection
{
private SqlConnecction _sqlConn = null;
public MySqlConnectionWrapper(string connectString)
{
_sqlConn = new SqlConnection(connectString);
}
public override void Open()
{
_sqlConn.Open();
}
//TODO: override everything else and pass on to _sqlConn...
protected override DbProviderFactory DbProviderFactory
{
//todo: return wrapped provider factory...
}
}
When using:
using (SomeDataContext dc = new SomeDataContext(new MySqlConnectionWrapper("connect strng"))
{
var q = from x in dc.SomeTable select x;
//...etc...
}
That said, do you really want to go down that road? You'll need to be able to parse the SQL statements and queries generated by L2S in order to modify them properly. If you can instead modify the linq queries to append whatever you want to add to them, that is probably a better alternative.
Remember that Linq queries are composable, so you can add 'extras' in a separate method if you have something that you want to add to many queries.
first thing come to my mind is to modify the query and return the result in Non-LINQ format
//Get linq-query as datatable-schema
public DataTable ToDataTable(System.Data.Linq.DataContext ctx, object query)
{
if (query == null)
{
throw new ArgumentNullException("query");
}
IDbCommand cmd = ctx.GetCommand((IQueryable)query);
System.Data.SqlClient.SqlDataAdapter adapter = new System.Data.SqlClient.SqlDataAdapter();
adapter.SelectCommand = (System.Data.SqlClient.SqlCommand)cmd;
DataTable dt = new DataTable("sd");
try
{
cmd.Connection.Open();
adapter.FillSchema(dt, SchemaType.Source);
adapter.Fill(dt);
}
finally
{
cmd.Connection.Close();
}
return dt;
}
try to add your condition to the selectCommand and see if it helps.
Try setting up a view in the DB that applies the security filter to the records as needed, and then when retrieving records through L2S. This will ensure that the records that you need will not be returned.
Alternatively, add a .Where() to the query before it is submitted that will apply the security filter. This will allow you to apply the filter programmatically (in case it needs to change based on the scenario).
Using Castle ActiveRecord / NHibernate: Is there a way you can force an ICriterion on all queries on a table?
For example, a good amount of of my tables have a "UserId" column. I might want to ensure that I am always selecting rows for the logged in user. I can easily create an ICriterion object, but I am forced to supply it for different methods: FindAll(), FindFirst(), FindLast() etc.
Is there a way to force a WHERE clause on all queries to a Castle ActiveRecord?
I finally found a great solution (using filters). Since Castle AR does not have any native API for mapping to NHibernate filters, this part was pretty much undocumented. So here goes.
This example filter, will make sure you will never get news more than a year old, no matter what kind of query you use on the ActiveRecord. You can probably think of more practical applications for this.
First, create an ActiveRecord "News".
Use the following code before you initialize ActiveRecordStarter.
ActiveRecordStarter.MappingRegisteredInConfiguration += MappingRegisteredInConfiguration;
Castle.ActiveRecord.Framework.InterceptorFactory.Create = () => { return new EnableFiltersInterceptor(); };
Then, add the missing function and class:
void MappingRegisteredInConfiguration(Castle.ActiveRecord.Framework.ISessionFactoryHolder holder)
{
var cfg = holder.GetConfiguration(typeof (ActiveRecordBase));
var typeParameters = new Dictionary<string, IType>
{
{"AsOfDate", NHibernateUtil.DateTime}
};
cfg.AddFilterDefinition(new FilterDefinition("Latest", "", typeParameters));
var mappings = cfg.CreateMappings(Dialect.GetDialect(cfg.Properties));
var newsMapping = cfg.GetClassMapping(typeof (News));
newsMapping.AddFilter("Latest", ":AsOfDate <= Date");
}
public class EnableFiltersInterceptor : EmptyInterceptor
{
public override void SetSession(ISession session)
{
session.EnableFilter("Latest").SetParameter("AsOfDate", DateTime.Now.AddYears(-1));
}
}
And voila! Queries on News, e.g. FindAll(), DeleteAll(), FindOne(), Exists(), etc. will never touch entries more than a year old.
The closest thing would be using filters. See http://ayende.com/Blog/archive/2009/05/04/nhibernate-filters.aspx