I am trying to read the size of my database, and I can do this in SQL Server - but how do I run the following code in Entity Framework and get the output?
USE Impro_V2
GO
sp_spaceused
GO
or
EXEC sp_helpdb N'Impro_V2';
Using context.Database.ExecuteSqlCommand I get a result of "-1". I am not even sure whether that is failed.
How do run code like that?
The answer is here:
How to know the physical size of the database in Entity Framework?
The code is simple:
var ef = new MyDbContext();
var sqlConn = ef.Database.Connection as SqlConnection;
var cmd = new SqlCommand("sp_spaceused")
{
CommandType = System.Data.CommandType.StoredProcedure,
Connection = sqlConn as SqlConnection
};
var adp = new SqlDataAdapter(cmd);
var dataset = new DataSet();
sqlConn.Open();
adp.Fill(dataset);
sqlConn.Close();
// example read
foreach (DataTable table in dataset.Tables)
{
foreach (DataRow row in table.Rows)
{
foreach (DataColumn col in table.Columns)
{
console.write(row[icol].tostring());
etc
I have min 100 000 data into a Job_Details table and I'm using Entity Framework to map the data.
This is the code:
public GetJobsResponse GetImportJobs()
{
GetJobsResponse getJobResponse = new GetJobsResponse();
List<JobBO> lstJobs = new List<JobBO>();
using (NSEXIM_V2Entities dbContext = new NSEXIM_V2Entities())
{
var lstJob = dbContext.Job_Details.ToList();
foreach (var dbJob in lstJob.Where(ie => ie.IMP_EXP == "I" && ie.Job_No != null))
{
JobBO job = MapBEJobforSearchObj(dbJob);
lstJobs.Add(job);
}
}
getJobResponse.Jobs = lstJobs;
return getJobResponse;
}
I found to this line is taking about 2-3 min to execute
var lstJob = dbContext.Job_Details.ToList();
How can i solve this issue?
To outline the performance issues with your example: (see inline comments)
public GetJobsResponse GetImportJobs()
{
GetJobsResponse getJobResponse = new GetJobsResponse();
List<JobBO> lstJobs = new List<JobBO>();
using (NSEXIM_V2Entities dbContext = new NSEXIM_V2Entities())
{
// Loads *ALL* entities into memory. This effectively takes all fields for all rows across from the database to your app server. (Even though you don't want it all)
var lstJob = dbContext.Job_Details.ToList();
// Filters from the data in memory.
foreach (var dbJob in lstJob.Where(ie => ie.IMP_EXP == "I" && ie.Job_No != null))
{
// Maps the entity to a DTO and adds it to the return collection.
JobBO job = MapBEJobforSearchObj(dbJob);
lstJobs.Add(job);
}
}
// Returns the DTOs.
getJobResponse.Jobs = lstJobs;
return getJobResponse;
}
First: pass your WHERE clause to EF to pass to the DB server rather than loading all entities into memory..
public GetJobsResponse GetImportJobs()
{
GetJobsResponse getJobResponse = new GetJobsResponse();
using (NSEXIM_V2Entities dbContext = new NSEXIM_V2Entities())
{
// Will pass the where expression to be DB server to be executed. Note: No .ToList() yet to leave this as IQueryable.
var jobs = dbContext.Job_Details..Where(ie => ie.IMP_EXP == "I" && ie.Job_No != null));
Next, use SELECT to load your DTOs. Typically these won't contain as much data as the main entity, and so long as you're working with IQueryable you can load related data as needed. Again this will be sent to the DB Server so you cannot use functions like "MapBEJobForSearchObj" here because the DB server does not know this function. You can SELECT a simple DTO object, or an anonymous type to pass to a dynamic mapper.
var dtos = jobs.Select(ie => new JobBO
{
JobId = ie.JobId,
// ... populate remaining DTO fields here.
}).ToList();
getJobResponse.Jobs = dtos;
return getJobResponse;
}
Moving the .ToList() to the end will materialize the data into your JobBO DTOs/ViewModels, pulling just enough data from the server to populate the desired rows and with the desired fields.
In cases where you may have a large amount of data, you should also consider supporting server-side pagination where you pass a page # and page size, then utilize a .Skip() + .Take() to load a single page of entries at a time.
Our current system is using Lazyloading by default (it is something I am going to be disabling but it can't be done right now)
For this basic query I want to return two tables, CustomerNote and Note.
This is my query
using (var newContext = new Entities(true))
{
newContext.Configuration.LazyLoadingEnabled = false;
var result = from customerNotes in newContext.CustomerNotes.Include(d=>d.Note)
join note in newContext.Notes
on customerNotes.NoteId equals note.Id
where customerNotes.CustomerId == customerId
select customerNotes;
return result.ToList();
}
My result however only contains the data in the CustomerNote table
The linked entities Customer and Note are both null, what am I doing wrong here?
I got it working with the following which is much simpler than what I've found elsewhere
Context.Configuration.LazyLoadingEnabled = false;
var result = Context.CustomerNotes.Where<CustomerNote>(d => d.CustomerId == customerId)
.Include(d=>d.Note)
.Include(d=>d.Note.User);
return result.ToList();
This returns my CustomerNote table, related Notes and related Users from the Notes.
That is callled eager loading you want to achieve.
var customerNotes = newContext.CustomerNotes.Include(t=> t.Node).ToList();
This should work, i don't really understand the keyword syntax.
If the code above doesn't work try this:
var customerNotes = newContext.CustomerNotes.Include(t=> t.Node).Select(t=> new {
Node = t.Node,
Item = t
}).ToList();
Does Entity Framework Core 1.0 Support multiple result set?
If so can you give please give an example based on the below stored procedure?
CREATE PROCEDURE uspGetProductInfo
AS
BEGIN
SELECT ID,PRODUCT_NAME FROM PRODUCT
SELECT ID,CATEGORY_NAME FROM PRODUCT_CATEGORY
END
What kind of support are you looking for? You can certainly drop-down to ADO.NET.
var command = db.Database.GetDbConnection().CreateCommand();
command.CommandText = "uspGetProductInfo";
db.Database.OpenConnection();
try
{
using (var reader = command.ExecuteReader())
{
while (reader.Read())
{
// TODO: Read products
}
reader.NextResult();
while (reader.Read())
{
// TODO: Read product categories
}
}
}
finally
{
db.Database.CloseConnection();
}
I am working with a system that has many stored procedures that need to be displayed. Creating entities for each of my objects is not practical.
Is it possible and how would I return a DataTable using ExecuteStoreQuery ?
public ObjectResult<DataTable> MethodName(string fileSetName) {
using (var dataContext = new DataContext(_connectionString))
{
var returnDataTable = ((IObjectContextAdapter)dataContext).ObjectContext.ExecuteStoreQuery<DataTable>("SP_NAME","SP_PARAM");
return returnDataTable;
}
Yes it's possible, but it should be used for just dynamic result-set or raw SQL.
public DataTable ExecuteStoreQuery(string commandText, params Object[] parameters)
{
DataTable retVal = new DataTable();
retVal = context.ExecuteStoreQuery<DataTable>(commandText, parameters).FirstOrDefault();
return retVal;
}
Edit: It's better to use classical ADO.NET to get the data model rather than using Entity Framework because most probably you cannot use DataTable even if you can run the method: context.ExecuteStoreQuery<DataTable>(commandText, parameters).FirstOrDefault();
ADO.NET Example:
public DataSet GetResultReport(int questionId)
{
DataSet retVal = new DataSet();
EntityConnection entityConn = (EntityConnection)context.Connection;
SqlConnection sqlConn = (SqlConnection)entityConn.StoreConnection;
SqlCommand cmdReport = new SqlCommand([YourSpName], sqlConn);
SqlDataAdapter daReport = new SqlDataAdapter(cmdReport);
using (cmdReport)
{
SqlParameter questionIdPrm = new SqlParameter("QuestionId", questionId);
cmdReport.CommandType = CommandType.StoredProcedure;
cmdReport.Parameters.Add(questionIdPrm);
daReport.Fill(retVal);
}
return retVal;
}
No, I don't think that'll work - Entity Framework is geared towards returning entities and isn't meant to return DataTable objects.
If you need DataTable objects, use straight ADO.NET instead.
This method uses the connection string from the entity framework to establish an ADO.NET connection, to a MySQL database in this example.
using MySql.Data.MySqlClient;
public DataSet GetReportSummary( int RecordID )
{
var context = new catalogEntities();
DataSet ds = new DataSet();
using ( MySqlConnection connection = new MySqlConnection( context.Database.Connection.ConnectionString ) )
{
using ( MySqlCommand cmd = new MySqlCommand( "ReportSummary", connection ) )
{
MySqlDataAdapter adapter = new MySqlDataAdapter( cmd );
adapter.SelectCommand.CommandType = CommandType.StoredProcedure;
adapter.SelectCommand.Parameters.Add( new MySqlParameter( "#ID", RecordID ) );
adapter.Fill( ds );
}
}
return ds;
}
Yes it can easily be done like this:
var table = new DataTable();
using (var ctx = new SomeContext())
{
var cmd = ctx.Database.Connection.CreateCommand();
cmd.CommandText = "Select Col1, Col2 from SomeTable";
cmd.Connection.Open();
table.Load(cmd.ExecuteReader());
}
By the rule, you shouldn't use a DataSet inside a EF application. But, if you really need to (for instance, to feed a report), that solution should work (it's EF 6 code):
DataSet GetDataSet(string sql, CommandType commandType, Dictionary<string, Object> parameters)
{
// creates resulting dataset
var result = new DataSet();
// creates a data access context (DbContext descendant)
using (var context = new MyDbContext())
{
// creates a Command
var cmd = context.Database.Connection.CreateCommand();
cmd.CommandType = commandType;
cmd.CommandText = sql;
// adds all parameters
foreach (var pr in parameters)
{
var p = cmd.CreateParameter();
p.ParameterName = pr.Key;
p.Value = pr.Value;
cmd.Parameters.Add(p);
}
try
{
// executes
context.Database.Connection.Open();
var reader = cmd.ExecuteReader();
// loop through all resultsets (considering that it's possible to have more than one)
do
{
// loads the DataTable (schema will be fetch automatically)
var tb = new DataTable();
tb.Load(reader);
result.Tables.Add(tb);
} while (!reader.IsClosed);
}
finally
{
// closes the connection
context.Database.Connection.Close();
}
}
// returns the DataSet
return result;
}
In my Entity Framework based solution I need to replace one of my Linq queries with sql - for efficiency reasons.
Also I want my results in a DataTable from one stored procedure so that I could create a table value parameter to pass into a second stored procedure. So:
I'm using sql
I don't want a DataSet
Iterating an IEnumerable probably isn't going to cut it - for efficiency reasons
Also, I am using EF6, so I would prefer DbContext.SqlQuery over ObjectContext.ExecuteStoreQuery as the original poster requested.
However, I found that this just didn't work:
_Context.Database.SqlQuery<DataTable>(sql, parameters).FirstOrDefault();
This is my solution. It returns a DataTable that is fetched using an ADO.NET SqlDataReader - which I believe is faster than a SqlDataAdapter on read-only data. It doesn't strictly answer the question because it uses ADO.Net, but it shows how to do that after getting a hold of the connection from the DbContext
protected DataTable GetDataTable(string sql, params object[] parameters)
{
//didn't work - table had no columns or rows
//return Context.Database.SqlQuery<DataTable>(sql, parameters).FirstOrDefault();
DataTable result = new DataTable();
SqlConnection conn = Context.Database.Connection as SqlConnection;
if(conn == null)
{
throw new InvalidCastException("SqlConnection is invalid for this database");
}
using (SqlCommand cmd = new SqlCommand(sql, conn))
{
cmd.Parameters.AddRange(parameters);
conn.Open();
using (SqlDataReader reader = cmd.ExecuteReader())
{
result.Load(reader);
}
return result;
}
}
The easiest way to return a DataTable using the EntityFramework is to do the following:
MetaTable metaTable = Global.DefaultModel.GetTable("Your EntitySetName");
For example:
MetaTable metaTable = Global.DefaultModel.GetTable("Employees");
Maybe your stored procedure could return a complex type?
http://blogs.msdn.com/b/somasegar/archive/2010/01/11/entity-framework-in-net-4.aspx