I have made a tiny software tool that allows me to display or run SQL generated from NHibernate. I made this because hbm2ddl.auto is not recommended for production.
I have one problem: when I generate the SQL I always get the infamous Index column unquoted, because I need .AsList() mappings. This prevents me to run the SQL.
In theory, if I had an XML configuration of NHibernate I could use hbm2ddl.keywords tag, but unfortunately since my tool is designed as a DBA-supporting tool for multiple environments, I must use a programmatic approach.
My approach (redundant) is the following:
private static Configuration BuildNHConfig(string connectionString, DbType dbType, out Dialect requiredDialect)
{
IPersistenceConfigurer persistenceConfigurer;
switch (dbType)
{
case DbType.MySQL:
{
persistenceConfigurer =
MySQLConfiguration
.Standard
.Dialect<MySQL5Dialect>()
.Driver<MySqlDataDriver>()
.FormatSql()
.ShowSql()
.ConnectionString(connectionString);
requiredDialect = new MySQL5Dialect();
break;
}
case DbType.MsSqlAzure:
{
persistenceConfigurer = MsSqlConfiguration.MsSql2008
.Dialect<MsSqlAzure2008Dialect>()
.Driver<SqlClientDriver>()
.FormatSql()
.ShowSql()
.ConnectionString(connectionString);
requiredDialect = new MsSqlAzure2008Dialect();
break;
}
default:
{
throw new NotImplementedException();
}
}
FluentConfiguration fc = Fluently.Configure()
.Database(persistenceConfigurer)
.ExposeConfiguration(
cfg => cfg.SetProperty("hbm2ddl.keywords", "keywords")
.SetProperty("hbm2ddl.auto", "none"))
.Mappings(
m => m.FluentMappings.AddFromAssemblyOf<NHibernateFactory>());
Configuration ret = fc.BuildConfiguration();
SchemaMetadataUpdater.QuoteTableAndColumns(ret);
return ret;
}
...
public static void GenerateSql(MainWindowViewModel viewModel)
{
Dialect requiredDialect;
Configuration cfg = BuildNHConfig(viewModel.ConnectionString, viewModel.DbType.Value, out requiredDialect);
StringBuilder sqlBuilder = new StringBuilder();
foreach (string sqlLine in cfg.GenerateSchemaCreationScript(requiredDialect))
sqlBuilder.AppendLine(sqlLine);
viewModel.Sql = sqlBuilder.ToString();
}
Explanation: when I want to set the ViewModel's SQL to display on a TextBox (yea, this is WPF) I initialize the configuration programmatically with connection string given in ViewModel and choose the dialect/provider accordingly. When I Fluently Configure NHibernate I both set hbm2ddl.keywords (tried both auto-quote and keywords, this being the default) and, following this blog post, I also use the SchemaMetadataUpdater.
The result is that I'm always presented with SQL like
create table `OrderHistoryEvent` (Id BIGINT NOT NULL AUTO_INCREMENT, EventType VARCHAR(255) not null, EventTime DATETIME not null, EntityType VARCHAR(255), Comments VARCHAR(255), Order_id VARCHAR(255), Index INTEGER, primary key (Id))
where the guilty Index column is not quoted.
The question is: given a programmatic and fluent configuration of NHibernate, how do I tell NHibernate to quote any reserved word in the SQL exported by GenerateSchemaCreationScript?
I have found a workaround: when I generate the update script (the one that runs with hbm2ddl.auto=update) the script is correctly quoted.
The infamous Index column has been already discussed and from my findings it's hardcoded in FNH (ToManyBase.cs, method public T AsList()).
Since the update script is a perfectly working creational script on an empty database, changing the code to generate an update script on an empty DB should equal generating a creational script.
This happens only because I want to generate the script on my own. There is probably a bug in NHibernate that only activates when you call GenerateSchemaCreationScript and not when you let your SessionFactory build the DB for you
Related
I am currently trying to migrate from an old MySQL (5.0) to MSSQL. Because I must keep the primary key relationships, I am now facing a problem. Some data inside a table begin with the id of 6102 instead of one. I can solve this by increasing the seed, which works. Now, after several thousand of data sets, I have some leaps e.g. from id 22569 to 22597. This occurres multiple times.
What I basically do at the moment is, select all data from the source db (MySQL), map them into a generated model und try to map this model to my target model (MSSQL). (I do this because the target, new structure differs a little from the existing one.) When I ignore those leaps, I am getting later on several other tables a foreign key violation.
So my solution currently would be, to count from the beginning each mapping and when the id of the current model differs from the counter, to reset manually the seed in the database.
DBCC CHECKIDENT (mytable, RESEED, idFromCurrentModel);
Is there a possibility to force entity framework, respectively SQL Server to accept the id from my model instead of ignoring it and use the ident value?
Thanks for reading and best regards
EDIT
Just if anybody is wondering how I solved this, here it is:
var context = new TestEntities();
// map mysql data to mssql model and convert data
// let's assume I did this
var mapped = new List<Test>()
{
new Test() {id= 42, bar = "foo", created = DateTime.Now},
new Test() {id= 1337, bar = "bar", created = DateTime.Now}
};
var transaction = context.Database.BeginTransaction();
context.Database.ExecuteSqlCommand("SET IDENTITY_INSERT [SeedingTest].[dbo].[Test] ON");
context.Test.AddRange(mapped);
context.SaveChanges();
context.Database.ExecuteSqlCommand("SET IDENTITY_INSERT [SeedingTest].[dbo].[Test] OFF");
transaction.Commit();
context.Dispose();
This only works when I do this:
Right click on my *.edmx file, open, and remove the
StoreGeneratedPattern="Identity"
in your identity column. In my case this looked like this:
...
<Property Name="id" Type="int" Nullable="false" StoreGeneratedPattern="Identity" />
...
After removing this, EF was no longer ignoring my set id's.
Source
Additional information:
Adding this attribute
[DatabaseGenerated(DatabaseGeneratedOption.None)]
to my id in my generated model, did not work.
[DatabaseGenerated(DatabaseGeneratedOption.None)]
public int foo { get; set; }
public string bar { get; set; }
...
The easiest way is to set the seed initially to the current max Id value + 1. Then, when inserting the converted rows do the following
set identity_insert on tablename -- stops generation of IDENTITY, requires user to supply it
insert into tablename values (Id....) -- supply value of Id
set identity_insert_off tablename -- turn inedtity generation back on
This does it quite nicely.
I'm using EF5.0 in an ASP.NET MVC app. My Entity Model is named 'DataModel'. Included in the model is a table-valued function that exists in my MSSQL database, named MatchingEntries. It returns a table of integer ids.
I've looked at the DataModel.Context.cs file, that gets generated via the .tt (T4) template file. It has the following code in it:
[EdmFunction("DataEntities", "MatchingEntries")]
public virtual IQueryable<Nullable<int>> MatchingEntries(string term)
{
var termParameter = term != null ?
new ObjectParameter("Term", term) :
new ObjectParameter("Term", typeof(string));
return ((IObjectContextAdapter)this).ObjectContext.CreateQuery<Nullable<int>>("[DataEntities].[MatchingEntries](#Term)", termParameter);
}
The error I am getting results from using this method twice within the one query, such as:
IQueryable<int> one = db.MatchingEntries("\"one*\"");
IQueryable<int> two = db.MatchingEntries("\"two*\"");
List<int> both = one.Intersect(two).ToList();
The error is:
A parameter named 'Term' already exists in the parameter collection. Parameter names must be unique in the parameter collection.
Parameter name: parameter
Is this a known limitation of the classes generated from an EDMX for table-valued functions? With LINQ2SQL I am able to execute this a a single query to the database (that does a JOIN between the 2 outputs from MatchingEntries) and it replaces the parameter name #Term with #p0 and #p1 for the two different instances of the call. I'd like to make Entity Framework do the same.
So, my question is, how can I get EF to work in the same manner and avoid the 'Duplicate parameter' error?
My fallback is to evaluate each call to db.MatchingEntries separately, by putting ToList() after them. My other idea has been to replace the ObjectParameter name in the T4 generated Context.cs class with something randomly generated each time. These feel like hacks that I should be able to avoid.
This answer is Linq to Entities specific. This doesn't have to be done in Linq to SQL (Linqpad).
Thanks to this question I got a pointer to a viable solution:
extend the autogenerated DBContext class (partial class)
add a method with two parameters in the partial class
at calling, pass an index as second parameter
Detailed Answer:
DataEntitys.my.cs:
[EdmFunction("DataEntities", "MatchingEntries")]
public virtual IQueryable<Nullable<int>> MatchingEntries(string term, int index)
{
string param_name = String.Format("k_{0}", index);
var termParameter = term != null ?
new ObjectParameter(param_name, term) :
new ObjectParameter(param_name, typeof(string));
return ((IObjectContextAdapter)this).
ObjectContext.CreateQuery<Nullable<int>>(
String.Format("[DataEntities].[MatchingEntries](#{0})", param_name),
termParameter);
}
Call the function:
foreach (string teil in such)
{
index++;
if (teil.Trim() != "")
res = res.Join(db.MatchingEntries("\"" + teil + "*\"", index), l => l.ID, s => s.KEY, (l, s) => l);
}
I have setup a test database and console app to confirm the following:
Given a SQL Database with the following function:
CREATE FUNCTION ufn_GTFO
(
#Guid as uniqueidentifier
)
RETURNS VARCHAR(100)
AS
BEGIN
-- Declare the return variable here
DECLARE #Result as VARCHAR(100)
-- Add the T-SQL statements to compute the return value here
SELECT #Result = 'This is a test'
-- Return the result of the function
RETURN #Result
END
GO
And the following table:
CREATE TABLE [dbo].[Test](
[PKey] [int] IDENTITY(1,1) NOT NULL,
[WFT] [uniqueidentifier] NULL,
CONSTRAINT [PK_Test] PRIMARY KEY CLUSTERED
(
[PKey] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
The Scalar valued function ufn_GTFO is normally composable, such that the following C#:
static void ConcreteTest()
{
DataClasses1DataContext db = new DataClasses1DataContext();
var q = from t in db.Tests
select new { t.PKey, GTFO = db.ufn_GTFO(t.WFT) };
var p = q.ToArray();
}
Is translated into the following SQL:
SELECT [t0].[PKey], [dbo].[ufn_GTFO]([t0].[WFT]) AS [GTFO] FROM [dbo].[Test] AS [t0]
However, if I use the refactor -> extract interface on the DataContext, and use an instance of that:
static void InterfaceTest()
{
IDataClasses1DataContext db = new DataClasses1DataContext();
var q = from t in db.Tests
select new { t.PKey, GTFO = db.ufn_GTFO(t.WFT) };
var p = q.ToArray();
}
I get the following SQL, and calls to ufn_GTFO occur once for each record as .ToArray() enumerates the results.
SELECT [t0].[PKey], [t0].[WFT] AS [guid]
FROM [dbo].[Test] AS [t0]
So, my question is why does this happen and what can I do to prevent it while still using the interface?
Update 1: I've compared the IL generated for the concrete method versus the interface method, and they differ only in the reference to the interface and a compiler generated display class that doesn't seem to have any bearing on the result.
linq to sql relies heavily on attributes to map class (datacontext) members to database members. Your interfaces likely does not have the FunctionAttribute over the ufn_GRFO method. without that attribute the link between the C# world and the SQL function is severed; however. your interface is also not decorated with the DatabaseAttribute as that attribute is only valid on classes and not interfaces. without that attribute you have severed the link between C# and the whole database. by default Linq uses the AttributeMappingSource to map type members in the DataContext. Sense the interface is the type in question and that type has severed the link to that database, due to the fact that you can't apply the database attribute to it, your default mapping source will not map the function ufn_GRFO to the database function, rather linq will treat it as a .NET function to call with the data from the WFT field.
I suspect the way around this issue is to provide your datacontext with a custom MappingSource implementation and that ignores the DatabaseAttribute and only considers the attributes on the properties.
http://msdn.microsoft.com/en-us/library/system.data.linq.mapping.functionattribute.aspx
http://msdn.microsoft.com/en-us/library/system.data.linq.mapping.databaseattribute.aspx
http://msdn.microsoft.com/en-us/library/system.data.linq.mapping.attributemappingsource.aspx
http://msdn.microsoft.com/en-us/library/system.data.linq.mapping.mappingsource.aspx
Not sure if I should raise an issue regarding this, so thought I would ask if anybody knew a simple workaround for this first. I am getting an error when I try to use Dapper with OleDbConnection when used in combination with MS Access 2003 (Jet.4.0) (not my choice of database!)
When running the test code below I get an exception 'OleDbException : Data type mismatch in criteria expression'
var count = 0;
using (var conn = new OleDbConnection(connString)) {
conn.Open();
var qry = conn.Query<TestTable>("select * from testtable where CreatedOn <= #CreatedOn;", new { CreatedOn = DateTime.Now });
count = qry.Count();
}
I believe from experience in the past with OleDb dates, is that when setting the DbType to Date, it then changes internally the value for OleDbType property to OleDbTimeStamp instead of OleDbType.Date. I understand this is not because of Dapper, but what 'could' be considered a strange way of linking internally in the OleDbParameter class
When dealing with this either using other ORMs, raw ADO or my own factory objects, I would clean up the command object just prior to running the command and change the OleDbType to Date.
This is not possible with Dapper as far as I can see as the command object appears to be internal. Unfortunately I have not had time to learn the dynamic generation stuff, so I could be missing something simple or I might suggest a fix and contribute rather than simply raise an issue.
Any thoughts?
Lee
It's an old thread but I had the same problem: Access doesn't like DateTime with milliseconds, so you have to add and extension method like this :
public static DateTime Floor(this DateTime date, TimeSpan span)
{
long ticks = date.Ticks / span.Ticks;
return new DateTime(ticks * span.Ticks, date.Kind);
}
And use it when passing parameters:
var qry = conn.Query<TestTable>("select * from testtable where CreatedOn <= #CreatedOn;", new { CreatedOn = DateTime.Now.Floor(TimeSpan.FromSeconds(1)) });
Unfortunately, with current Dapper version (1.42), we cannot add custom TypeHandler for base types (see #206).
If you can modify Dapper (use the cs file and not the DLL) merge this pull request and then you do not have to use Floor on each parameters :
public class DateTimeTypeHandler : SqlMapper.TypeHandler<DateTime>
{
public override DateTime Parse(object value)
{
if (value == null || value is DBNull)
{
return default(DateTime);
}
return (DateTime)value;
}
public override void SetValue(IDbDataParameter parameter, DateTime value)
{
parameter.DbType = DbType.DateTime;
parameter.Value = value.Floor(TimeSpan.FromSeconds(1));
}
}
SqlMapper.AddTypeHandler<DateTime>(new DateTimeTypeHandler());
Hallo,
I have web service that has multiple methods that can be called. Each time one of these methods is called I am logging the call to a statistics database so we know how many times each method is called each month and the average process time.
Each time I log statistic data I first check the database to see if that method for the current month already exists, if not the row is created and added. If it already exists I update the needed columns to the database.
My problem is that sometimes when I update a row I get the "Row not found or changed" exception and yes I know it is because the row has been modified since I read it.
To solve this I have tried using the following without success:
Use using around my datacontext.
Use using around a TransactionScope.
Use a mutex, this doesn’t work because the web service is (not sure I am calling it the right think) replicated out on different PC for performance but still using the same database.
Resolve concurrency conflict in the exception, this doesn’t work because I need to get the new database value and add a value to it.
Below I have added the code used to log the statistics data. Any help would be appreciated very much.
public class StatisticsGateway : IStatisticsGateway
{
#region member variables
private StatisticsDataContext db;
#endregion
#region Singleton
[ThreadStatic]
private static IStatisticsGateway instance;
[ThreadStatic]
private static DateTime lastEntryTime = DateTime.MinValue;
public static IStatisticsGateway Instance
{
get
{
if (!lastEntryTime.Equals(OperationState.EntryTime) || instance == null)
{
instance = new StatisticsGateway();
lastEntryTime = OperationState.EntryTime;
}
return instance;
}
}
#endregion
#region constructor / initialize
private StatisticsGateway()
{
var configurationAppSettings = new System.Configuration.AppSettingsReader();
var connectionString = ((string)(configurationAppSettings.GetValue("sqlConnection1.ConnectionString", typeof(string))));
db = new StatisticsDataContext(connectionString);
}
#endregion
#region IStatisticsGateway members
public void AddStatisticRecord(StatisticRecord record)
{
using (db)
{
var existing = db.Statistics.SingleOrDefault(p => p.MethodName == record.MethodName &&
p.CountryID == record.CountryID &&
p.TokenType == record.TokenType &&
p.Year == record.Year &&
p.Month == record.Month);
if (existing == null)
{
//Add new row
this.AddNewRecord(record);
return;
}
//Update
existing.Count += record.Count;
existing.TotalTimeValue += record.TotalTimeValue;
db.SubmitChanges();
}
}
I would suggest letting SQL Server deal with the concurrency.
Here's how:
Create a stored procedure that accepts your log values (method name, month/date, and execution statistics) as arguments.
In the stored procedure, before anything else, get an application lock as described here, and here. Now you can be sure only one instance of the stored procedure will be running at once. (Disclaimer! I have not tried sp_getapplock myself. Just saying. But it seems fairly straightforward, given all the examples out there on the interwebs.)
Next, in the stored procedure, query the log table for a current-month's entry for the method to determine whether to insert or update, and then do the insert or update.
As you may know, in VS you can drag stored procedures from the Server Explorer into the DBML designer for easy access with LINQ to SQL.
If you're trying to avoid stored procedures then this solution obviously won't be for you, but it's how I'd solve it easily and quickly. Hope it helps!
If you don't want to use the stored procedure approach, a crude way of dealing with it would simply be retrying on that specific exception. E.g:
int maxRetryCount = 5;
for (int i = 0; i < maxRetryCount; i++)
{
try
{
QueryAndUpdateDB();
break;
}
catch(RowUpdateException ex)
{
if (i == maxRetryCount) throw;
}
}
I have not used the sp_getapplock, instead I have used HOLDLOCK and ROWLOCK as seen below:
CREATE PROCEDURE [dbo].[UpdateStatistics]
#MethodName as varchar(50) = null,
#CountryID as varchar(2) = null,
#TokenType as varchar(5) = null,
#Year as int,
#Month as int,
#Count bigint,
#TotalTimeValue bigint
AS
BEGIN
SET NOCOUNT ON;
BEGIN TRAN
UPDATE dbo.[Statistics]
WITH (HOLDLOCK, ROWLOCK)
SET Count = Count + #Count
WHERE MethodName=#MethodName and CountryID=#CountryID and TokenType=#TokenType and Year=#Year and Month=#Month
IF ##ROWCOUNT=0
INSERT INTO dbo.[Statistics] (MethodName, CountryID, TokenType, TotalTimeValue, Year, Month, Count) values (#MethodName, #CountryID, #TokenType, #TotalTimeValue, #Year, #Month, #Count)
COMMIT TRAN
END
GO
I have tested it by calling my web service methods by multiple threads simultaneous and each call is logged without any problems.