General Data Context Extension Methods

This topic describes the general data context extension methods.

• NoTracking
• Open / OpenAsync
• HasChanges
• GetCommand
• CheckAndUpdateKeys
• GetMethodInfo

This extension method is used to turn off query tracking in a data context when constructed or later. This can improve performance if all you are doing is reading data without any updates. It can be chained together with the Open extension method described below to open the connection at the same time.

using var dataContext = new MyDbContext().NoTracking();

... Execute commands ...

using var dataContext = new MyDbContext().NoTracking().Open();

... Execute commands ...

This extension method and its asynchronous counterpart are used to open a connection on a data context when constructed or later. It can be chained together with the NoTracking extension method described above to turn off change tracking at the same time.

using var dataContext = new MyDbContext().Open();

... Execute commands ...

using var dataContext = new MyDbContext().NoTracking().Open();

... Execute commands ...

using var dataContext = await new MyDbContext().NoTracking().OpenAsync(cts.Token);

... Execute commands ...

This extension method can be used to see if a data context has any unsaved changes.

if(dataContext.HasChanges())
    dataContext.SaveChanges();

This extension method is used to get a command object in a state ready to execute the specified command text on the given data context. The command will be associated with the connection from the data context instance on which this method is called with the command timeout set to the value from the data context if one has been set. The command text can be a stored procedure with or without parameters or a literal SQL statement. The returned command is ready to execute or modify further with parameters. This is useful for situations in which a SqlDataReader is needed, you need more control when executing a stored procedure, or the stored procedure returns multiple result sets.

using var dataContext = new MyDbContext().NoTracking();

// Set up the daily schedule command and data adapter
var cmdDailySchedule = dc.GetCommand("spDailyScheduleInfo",
    new SqlParameter("@paramBidGroup", SqlDbType.Char, 4),
    new SqlParameter("@paramDate", SqlDbType.DateTime));

var daDailySchedule = new SqlDataAdapter(cmdDailySchedule);

This extension method is used to check for null keys or incomplete rows added by controls and either remove them or update them based on the passed in delegate methods. In certain cases, some list controls like data grids add a temporary row for new additions. If the row is left without saving changes or the changes are cancelled, the row is not always removed and still exists when changes are saved. Because it has null keys or missing values, it should not be kept. This extension method can be used to find such rows and remove them. It can also be used to update keys or other fields in new or existing rows if necessary.

The nullKeyCheck function delegate is used to check for these incomplete rows. If it returns true, the row is assumed to be an empty row and is detached. If it returns false or is not specified, the updateKeys action delegate is called to update keys or other fields as needed. If one is not specified, no further action is taken.

// If a list control added a row but left it incomplete, delete it.  If not, update the parent key.
dataContext.CheckAndUpdateKeys<ChildTable>(
    (entity, state) => state == EntityState.Added && entity.GroupId == null,
    (entity, state) => entity.ParentId = parent.ParentId);

This extension method is used within stored procedure data context methods to get the method information for the calling method. This information is used to get the parameter names and data types for use in the stored procedure method call. This extension method can be used to obtain the necessary method information whether the stored procedure method is called synchronously or asynchronously.

[MethodStoredProcedure("spStateCodeAddUpdate")]
public int AddOrUpdateStateCode(string? oldState, string? state, string? stateDesc)
{
    return this.ExecuteMethodNonQuery(this.GetMethodInfo(), oldState, state, stateDesc).ReturnValue;
}

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