I have the following method that waits for an exclusive lock on a Redis key. This method works but I'm wondering if there is a better way without a for loop and a Thread.Sleep.
/// <summary>
/// wait up to 2 seconds to achieve a lock!
/// The lock is good for a maximum of 3 seconds
/// </summary>
/// <param name="codeID"></param>
internal void WaitForSingleUseLock(CodeID codeID)
{
var key = _redemptionRepo.SingleUseCodeLockPrefix + codeID.Value;
var expiration = TimeSpan.FromSeconds(3);
for (var i = 0; i < 20; i++)
{
var lockAchieved = _cacheRepo.LockTake(key, "1", expiration);
if (lockAchieved)
{
break;
}
Thread.Sleep(TimeSpan.FromMilliseconds(100));
}
}
The only thing I could suggest different would be to consider pub/sub as a side channel (meaning: in addition, not replacement) for indicating when the lock might now be available - i.e. publish when releasing, and use the sub to release a timer (via a monitor or an async-wait-handle).
Other than that: nope. Redis doesn't have the idea of a pending queue. You could perhaps possibly construct one using lists, but...
After taking #Marc's comments into consideration and meeting with my team about the benefits of Task.Delay() over Thread.Sleep() in this context I decided on this as a final solution:
/// <summary>
/// wait up to 3 seconds to achieve a lock!
/// The lock is good for a maximum of 3 seconds
///
/// Returns the total amount of time until the lock was taken
/// </summary>
internal virtual async Task<TimeSpan> WaitForSingleUseLock(CodeID codeID)
{
var key = _redemptionRepo.SingleUseCodeLockPrefix + codeID.Value;
var totalTime = TimeSpan.Zero;
var maxTime = TimeSpan.FromSeconds(3);
var expiration = TimeSpan.FromSeconds(3);
var sleepTime = TimeSpan.FromMilliseconds(50);
var lockAchieved = false;
while (!lockAchieved && totalTime < maxTime)
{
lockAchieved = _cacheRepo.LockTake(key, "1", expiration);
if (lockAchieved)
{
continue;
}
await Task.Delay(sleepTime);
totalTime += sleepTime;
}
return totalTime;
}
Here's the table
Users
UserId
UserName
Password
EmailAddress
and the code..
public void ChangePassword(int userId, string password){
//code to update the password..
}
Ladislav's answer updated to use DbContext (introduced in EF 4.1):
public void ChangePassword(int userId, string password)
{
var user = new User() { Id = userId, Password = password };
using (var db = new MyEfContextName())
{
db.Users.Attach(user);
db.Entry(user).Property(x => x.Password).IsModified = true;
db.SaveChanges();
}
}
You can tell entity-framework which properties have to be updated in this way:
public void ChangePassword(int userId, string password)
{
var user = new User { Id = userId, Password = password };
using (var context = new ObjectContext(ConnectionString))
{
var users = context.CreateObjectSet<User>();
users.Attach(user);
context.ObjectStateManager.GetObjectStateEntry(user)
.SetModifiedProperty("Password");
context.SaveChanges();
}
}
In Entity Framework Core, Attach returns the entry, so all you need is:
var user = new User { Id = userId, Password = password };
db.Users.Attach(user).Property(x => x.Password).IsModified = true;
db.SaveChanges();
You have basically two options:
go the EF way all the way, in that case, you would
load the object based on the userId provided - the entire object gets loaded
update the password field
save the object back using the context's .SaveChanges() method
In this case, it's up to EF how to handle this in detail. I just tested this, and in the case I only change a single field of an object, what EF creates is pretty much what you'd create manually, too - something like:
`UPDATE dbo.Users SET Password = #Password WHERE UserId = #UserId`
So EF is smart enough to figure out what columns have indeed changed, and it will create a T-SQL statement to handle just those updates that are in fact necessary.
you define a stored procedure that does exactly what you need, in T-SQL code (just update the Password column for the given UserId and nothing else - basically executes UPDATE dbo.Users SET Password = #Password WHERE UserId = #UserId) and you create a function import for that stored procedure in your EF model and you call this function instead of doing the steps outlined above
i'm using this:
entity:
public class Thing
{
[Key]
public int Id { get; set; }
public string Info { get; set; }
public string OtherStuff { get; set; }
}
dbcontext:
public class MyDataContext : DbContext
{
public DbSet<Thing > Things { get; set; }
}
accessor code:
MyDataContext ctx = new MyDataContext();
// FIRST create a blank object
Thing thing = ctx.Things.Create();
// SECOND set the ID
thing.Id = id;
// THIRD attach the thing (id is not marked as modified)
db.Things.Attach(thing);
// FOURTH set the fields you want updated.
thing.OtherStuff = "only want this field updated.";
// FIFTH save that thing
db.SaveChanges();
While searching for a solution to this problem, I found a variation on GONeale's answer through Patrick Desjardins' blog:
public int Update(T entity, Expression<Func<T, object>>[] properties)
{
DatabaseContext.Entry(entity).State = EntityState.Unchanged;
foreach (var property in properties)
{
var propertyName = ExpressionHelper.GetExpressionText(property);
DatabaseContext.Entry(entity).Property(propertyName).IsModified = true;
}
return DatabaseContext.SaveChangesWithoutValidation();
}
"As you can see, it takes as its second parameter an expression of a
function. This will let use this method by specifying in a Lambda
expression which property to update."
...Update(Model, d=>d.Name);
//or
...Update(Model, d=>d.Name, d=>d.SecondProperty, d=>d.AndSoOn);
( A somewhat similar solution is also given here: https://stackoverflow.com/a/5749469/2115384 )
The method I am currently using in my own code, extended to handle also (Linq) Expressions of type ExpressionType.Convert. This was necessary in my case, for example with Guid and other object properties. Those were 'wrapped' in a Convert() and therefore not handled by System.Web.Mvc.ExpressionHelper.GetExpressionText.
public int Update(T entity, Expression<Func<T, object>>[] properties)
{
DbEntityEntry<T> entry = dataContext.Entry(entity);
entry.State = EntityState.Unchanged;
foreach (var property in properties)
{
string propertyName = "";
Expression bodyExpression = property.Body;
if (bodyExpression.NodeType == ExpressionType.Convert && bodyExpression is UnaryExpression)
{
Expression operand = ((UnaryExpression)property.Body).Operand;
propertyName = ((MemberExpression)operand).Member.Name;
}
else
{
propertyName = System.Web.Mvc.ExpressionHelper.GetExpressionText(property);
}
entry.Property(propertyName).IsModified = true;
}
dataContext.Configuration.ValidateOnSaveEnabled = false;
return dataContext.SaveChanges();
}
New EF Core 7 native feature — ExecuteUpdate:
Finally! After a long wait, EF Core 7.0 now has a natively supported way to run UPDATE (and also DELETE) statements while also allowing you to use arbitrary LINQ queries (.Where(u => ...)), without having to first retrieve the relevant entities from the database: The new built-in method called ExecuteUpdate — see "What's new in EF Core 7.0?".
ExecuteUpdate is precisely meant for these kinds of scenarios, it can operate on any IQueryable instance, and lets you update specific columns on any number of rows, while always issuing a single UPDATE statement behind the scenes, making it as efficient as possible.
Usage:
Let's take OP's example — i.e. updating the password column of a specific user:
dbContext.Users
.Where(u => u.Id == someId)
.ExecuteUpdate(b =>
b.SetProperty(u => u.Password, "NewPassword")
);
As you can see, calling ExecuteUpdate requires you to make calls to the SetProperty method, to specify which property to update, and also what new value to assign to it.
EF Core will translate this into the following UPDATE statement:
UPDATE [u]
SET [u].[Password] = "NewPassword"
FROM [Users] AS [u]
WHERE [u].[Id] = someId
Also, ExecuteDelete for deleting rows:
There's also a counterpart to ExecuteUpdate called ExecuteDelete, which, as the name implies, can be used to delete a single or multiple rows at once without having to first fetch them.
Usage:
// Delete users that haven't been active in 2022:
dbContext.Users
.Where(u => u.LastActiveAt.Year < 2022)
.ExecuteDelete();
Similar to ExecuteUpdate, ExecuteDelete will generate DELETE SQL statements behind the scenes — in this case, the following one:
DELETE FROM [u]
FROM [Users] AS [u]
WHERE DATEPART(year, [u].[LastActiveAt]) < 2022
Other notes:
Keep in mind that both ExecuteUpdate and ExecuteDelete are "terminating", meaning that the update/delete operation will take place as soon as you call the method. You're not supposed to call dbContext.SaveChanges() afterwards.
If you're curious about the SetProperty method, and you're confused as to why ExectueUpdate doesn't instead receive a member initialization expression (e.g. .ExecuteUpdate(new User { Email = "..." }), then refer to this comment (and the surrounding ones) on the GitHub issue for this feature.
Furthermore, if you're curious about the rationale behind the naming, and why the prefix Execute was picked (there were also other candidates), refer to this comment, and the preceding (rather long) conversation.
Both methods also have async equivalents, named ExecuteUpdateAsync, and ExecuteDeleteAsync respectively.
In EntityFramework Core 2.x there is no need for Attach:
// get a tracked entity
var entity = context.User.Find(userId);
entity.someProp = someValue;
// other property changes might come here
context.SaveChanges();
Tried this in SQL Server and profiling it:
exec sp_executesql N'SET NOCOUNT ON;
UPDATE [User] SET [someProp] = #p0
WHERE [UserId] = #p1;
SELECT ##ROWCOUNT;
',N'#p1 int,#p0 bit',#p1=1223424,#p0=1
Find ensures that already loaded entities do not trigger a SELECT and also automatically attaches the entity if needed (from the docs):
Finds an entity with the given primary key values. If an entity with the given primary key values is being tracked by the context, then it is returned immediately without making a request to the database. Otherwise, a query is made to the database for an entity with the given primary key values and this entity, if found, is attached to the context and returned. If no entity is found, then null is returned.
I'm late to the game here, but this is how I am doing it, I spent a while hunting for a solution I was satisified with; this produces an UPDATE statement ONLY for the fields that are changed, as you explicitly define what they are through a "white list" concept which is more secure to prevent web form injection anyway.
An excerpt from my ISession data repository:
public bool Update<T>(T item, params string[] changedPropertyNames) where T
: class, new()
{
_context.Set<T>().Attach(item);
foreach (var propertyName in changedPropertyNames)
{
// If we can't find the property, this line wil throw an exception,
//which is good as we want to know about it
_context.Entry(item).Property(propertyName).IsModified = true;
}
return true;
}
This could be wrapped in a try..catch if you so wished, but I personally like my caller to know about the exceptions in this scenario.
It would be called in something like this fashion (for me, this was via an ASP.NET Web API):
if (!session.Update(franchiseViewModel.Franchise, new[]
{
"Name",
"StartDate"
}))
throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.NotFound));
Entity framework tracks your changes on objects that you queried from database via DbContext. For example if you DbContext instance name is dbContext
public void ChangePassword(int userId, string password){
var user = dbContext.Users.FirstOrDefault(u=>u.UserId == userId);
user.password = password;
dbContext.SaveChanges();
}
I know this is an old thread but I was also looking for a similar solution and decided to go with the solution #Doku-so provided. I'm commenting to answer the question asked by #Imran Rizvi , I followed #Doku-so link that shows a similar implementation. #Imran Rizvi's question was that he was getting an error using the provided solution 'Cannot convert Lambda expression to Type 'Expression> [] ' because it is not a delegate type'. I wanted to offer a small modification I made to #Doku-so's solution that fixes this error in case anyone else comes across this post and decides to use #Doku-so's solution.
The issue is the second argument in the Update method,
public int Update(T entity, Expression<Func<T, object>>[] properties).
To call this method using the syntax provided...
Update(Model, d=>d.Name, d=>d.SecondProperty, d=>d.AndSoOn);
You must add the 'params' keyword in front of the second arugment as so.
public int Update(T entity, params Expression<Func<T, object>>[] properties)
or if you don't want to change the method signature then to call the Update method you need to add the 'new' keyword, specify the size of the array, then finally use the collection object initializer syntax for each property to update as seen below.
Update(Model, new Expression<Func<T, object>>[3] { d=>d.Name }, { d=>d.SecondProperty }, { d=>d.AndSoOn });
In #Doku-so's example he is specifying an array of Expressions so you must pass the properties to update in an array, because of the array you must also specify the size of the array. To avoid this you could also change the expression argument to use IEnumerable instead of an array.
Here is my implementation of #Doku-so's solution.
public int Update<TEntity>(LcmsEntities dataContext, DbEntityEntry<TEntity> entityEntry, params Expression<Func<TEntity, object>>[] properties)
where TEntity: class
{
entityEntry.State = System.Data.Entity.EntityState.Unchanged;
properties.ToList()
.ForEach((property) =>
{
var propertyName = string.Empty;
var bodyExpression = property.Body;
if (bodyExpression.NodeType == ExpressionType.Convert
&& bodyExpression is UnaryExpression)
{
Expression operand = ((UnaryExpression)property.Body).Operand;
propertyName = ((MemberExpression)operand).Member.Name;
}
else
{
propertyName = System.Web.Mvc.ExpressionHelper.GetExpressionText(property);
}
entityEntry.Property(propertyName).IsModified = true;
});
dataContext.Configuration.ValidateOnSaveEnabled = false;
return dataContext.SaveChanges();
}
Usage:
this.Update<Contact>(context, context.Entry(modifiedContact), c => c.Active, c => c.ContactTypeId);
#Doku-so provided a cool approach using generic's, I used the concept to solve my issue but you just can't use #Doku-so's solution as is and in both this post and the linked post no one answered the usage error questions.
Combining several suggestions I propose the following:
async Task<bool> UpdateDbEntryAsync<T>(T entity, params Expression<Func<T, object>>[] properties) where T : class
{
try
{
var entry = db.Entry(entity);
db.Set<T>().Attach(entity);
foreach (var property in properties)
entry.Property(property).IsModified = true;
await db.SaveChangesAsync();
return true;
}
catch (Exception ex)
{
System.Diagnostics.Debug.WriteLine("UpdateDbEntryAsync exception: " + ex.Message);
return false;
}
}
called by
UpdateDbEntryAsync(dbc, d => d.Property1);//, d => d.Property2, d => d.Property3, etc. etc.);
Or by
await UpdateDbEntryAsync(dbc, d => d.Property1);
Or by
bool b = UpdateDbEntryAsync(dbc, d => d.Property1).Result;
I use ValueInjecter nuget to inject Binding Model into database Entity using following:
public async Task<IHttpActionResult> Add(CustomBindingModel model)
{
var entity= await db.MyEntities.FindAsync(model.Id);
if (entity== null) return NotFound();
entity.InjectFrom<NoNullsInjection>(model);
await db.SaveChangesAsync();
return Ok();
}
Notice the usage of custom convention that doesn't update Properties if they're null from server.
ValueInjecter v3+
public class NoNullsInjection : LoopInjection
{
protected override void SetValue(object source, object target, PropertyInfo sp, PropertyInfo tp)
{
if (sp.GetValue(source) == null) return;
base.SetValue(source, target, sp, tp);
}
}
Usage:
target.InjectFrom<NoNullsInjection>(source);
Value Injecter V2
Lookup this answer
Caveat
You won't know whether the property is intentionally cleared to null OR it just didn't have any value it. In other words, the property value can only be replaced with another value but not cleared.
_context.Users.UpdateProperty(p => p.Id, request.UserId, new UpdateWrapper<User>()
{
Expression = p => p.FcmId,Value = request.FcmId
});
await _context.SaveChangesAsync(cancellationToken);
Update Property is an extension method
public static void UpdateProperty<T, T2>(this DbSet<T> set, Expression<Func<T, T2>> idExpression,
T2 idValue,
params UpdateWrapper<T>[] updateValues)
where T : class, new()
{
var entity = new T();
var attach = set.Attach(entity);
attach.Property(idExpression).IsModified = false;
attach.Property(idExpression).OriginalValue = idValue;
foreach (var update in updateValues)
{
attach.Property(update.Expression).IsModified = true;
attach.Property(update.Expression).CurrentValue = update.Value;
}
}
And Update Wrapper is a class
public class UpdateWrapper<T>
{
public Expression<Func<T, object>> Expression { get; set; }
public object Value { get; set; }
}
I was looking for same and finally I found the solution
using (CString conn = new CString())
{
USER user = conn.USERs.Find(CMN.CurrentUser.ID);
user.PASSWORD = txtPass.Text;
conn.SaveChanges();
}
believe me it work for me like a charm.
public async Task<bool> UpdateDbEntryAsync(TEntity entity, params Expression<Func<TEntity, object>>[] properties)
{
try
{
this.Context.Set<TEntity>().Attach(entity);
EntityEntry<TEntity> entry = this.Context.Entry(entity);
entry.State = EntityState.Modified;
foreach (var property in properties)
entry.Property(property).IsModified = true;
await this.Context.SaveChangesAsync();
return true;
}
catch (Exception ex)
{
throw ex;
}
}
public void ChangePassword(int userId, string password)
{
var user = new User{ Id = userId, Password = password };
using (var db = new DbContextName())
{
db.Entry(user).State = EntityState.Added;
db.SaveChanges();
}
}
I am developing a windows app that performs some common TFS tasks using the 2010 Beta 2 API (like creating new team projects, new work items, selective build, etc. ).
In the process of editing existing work items, I should be able to automatically set the 'Reason' field's values according to state change of the WI (mimic-ing Visual Studio). (eg)- When I edit a bug, when state changes from Active to Resolved, the default Reason is 'Fixed' and similarly the default Reason='Deferred' when state goes from Active to Closed. (As defined in the work item type definition xml file. ) This transition is easy to capture and implement inside a simple event handler on the form, since the initial state will be Active when the Bug is edited for the first time.
I want to know how to implement the remaining transitions like Resolved to Closed (Reason=Fixed), Resolved to Active (Reason=Test failed/Not fixed) or Closed to Active (Reason=Reactivated/Regression).
I know there is a method called WorkItem.GetNextState(current_state,action), but this doesn't help as it requires a specific action.
What I have done so far is shown below:
void cmbBugState_SelectedIndexChanged(object sender, EventArgs e)
{
//private enum bugWorkFlows{"Fixed","Deferred","Duplicate","As Designed","Cannot Reproduce","Obsolete","Test Failed","Not Fixed","Reactivated","Regression"}
string[] activeToResolvedReasons = { "Fixed", "Deferred", "Duplicate", "As Designed", "Cannot Reproduce", "Obsolete" };
string[] resolvedToActiveReasons = { "Test Failed", "Not fixed" };
string[] resolvedToClosedReasons = activeToResolvedReasons;
string[] closedToActiveReasons = { "Reactivated", "Regression" };
string[] activeToClosedReasons = activeToResolvedReasons;
cmbBugReason.Items.AddRange(activeToResolvedReasons);
// Set the default reason according to change of state of the work item.
if (cmbBugState.SelectedItem.ToString() == "Resolved")
{
cmbBugReason.Enabled = true;
cmbBugReason.SelectedItem = activeToResolvedReasons[0];
}
if (cmbBugState.SelectedItem.ToString() == "Closed")
{
cmbBugReason.Enabled = true;
cmbBugReason.SelectedItem = activeToResolvedReasons[1];
}
}
Can anyone show how to handle these events on the form?
Thanks,
Tara.
I tried GetNextState. It was never reliable enough for what I needed.
So I "rolled my own" state transition code that has worked very well for me when I am moving from State "A" to State "B". It is a bit long, but it should have what you are looking for in it.
As a side note: Because this does not use the GetNextState method it has to get the next state somehow. The way it does this is by downloading the XML of the work item type in question. It parses that out and uses that to make a Transition list (_allTransistions).
The permissions levels in TFS 2010 needed to do this are: Team Foundation Administrators or Project Administrators. (As a side note, in TFS 2008 and 2005 all valid users could do this.)
The full code that uses this can be found in the WorkItemHelpers.cs file in the TFS Aggregator project on codeplex.
public static void TransitionToState(this WorkItem workItem, string state, string commentPrefix)
{
// Set the sourceWorkItem's state so that it is clear that it has been moved.
string originalState = (string)workItem.Fields["State"].Value;
// Try to set the state of the source work item to the "Deleted/Moved" state (whatever is defined in the file).
// We need an open work item to set the state
workItem.TryOpen();
// See if we can go directly to the planned state.
workItem.Fields["State"].Value = state;
if (workItem.Fields["State"].Status != FieldStatus.Valid)
{
// Revert back to the orginal value and start searching for a way to our "MovedState"
workItem.Fields["State"].Value = workItem.Fields["State"].OriginalValue;
// If we can't then try to go from the current state to another state. Saving each time till we get to where we are going.
foreach (string curState in workItem.Type.FindNextState((string)workItem.Fields["State"].Value, state))
{
string comment;
if (curState == state)
comment = commentPrefix + Environment.NewLine + " State changed to " + state;
else
comment = commentPrefix + Environment.NewLine + " State changed to " + curState + " as part of move toward a state of " + state;
bool success = ChangeWorkItemState(workItem, originalState, curState, comment);
// If we could not do the incremental state change then we are done. We will have to go back to the orginal...
if (!success)
break;
}
}
else
{
// Just save it off if we can.
string comment = commentPrefix + "\n State changed to " + state;
ChangeWorkItemState(workItem, originalState, state, comment);
}
}
private static bool ChangeWorkItemState(this WorkItem workItem, string orginalSourceState, string destState, String comment)
{
// Try to save the new state. If that fails then we also go back to the orginal state.
try
{
workItem.TryOpen();
workItem.Fields["State"].Value = destState;
workItem.History = comment;
workItem.Save();
return true;
}
catch (Exception)
{
// Revert back to the original value.
workItem.Fields["State"].Value = orginalSourceState;
return false;
}
}
/// <summary>
/// Used to find the next state on our way to a destination state.
/// (Meaning if we are going from a "Not-Started" to a "Done" state,
/// we usually have to hit a "in progress" state first.
/// </summary>
/// <param name="wiType"></param>
/// <param name="fromState"></param>
/// <param name="toState"></param>
/// <returns></returns>
public static IEnumerable<string> FindNextState(this WorkItemType wiType, string fromState, string toState)
{
var map = new Dictionary<string, string>();
var edges = wiType.GetTransitions().ToDictionary(i => i.From, i => i.To);
var q = new Queue<string>();
map.Add(fromState, null);
q.Enqueue(fromState);
while (q.Count > 0)
{
var current = q.Dequeue();
foreach (var s in edges[current])
{
if (!map.ContainsKey(s))
{
map.Add(s, current);
if (s == toState)
{
var result = new Stack<string>();
var thisNode = s;
do
{
result.Push(thisNode);
thisNode = map[thisNode];
} while (thisNode != fromState);
while (result.Count > 0)
yield return result.Pop();
yield break;
}
q.Enqueue(s);
}
}
}
// no path exists
}
private static readonly Dictionary<WorkItemType, List<Transition>> _allTransistions = new Dictionary<WorkItemType, List<Transition>>();
/// <summary>
/// Deprecated
/// Get the transitions for this <see cref="WorkItemType"/>
/// </summary>
/// <param name="workItemType"></param>
/// <returns></returns>
public static List<Transition> GetTransitions(this WorkItemType workItemType)
{
List<Transition> currentTransistions;
// See if this WorkItemType has already had it's transistions figured out.
_allTransistions.TryGetValue(workItemType, out currentTransistions);
if (currentTransistions != null)
return currentTransistions;
// Get this worktype type as xml
XmlDocument workItemTypeXml = workItemType.Export(false);
// Create a dictionary to allow us to look up the "to" state using a "from" state.
var newTransistions = new List<Transition>();
// get the transistions node.
XmlNodeList transitionsList = workItemTypeXml.GetElementsByTagName("TRANSITIONS");
// As there is only one transistions item we can just get the first
XmlNode transitions = transitionsList[0];
// Iterate all the transitions
foreach (XmlNode transitionXML in transitions)
{
// See if we have this from state already.
string fromState = transitionXML.Attributes["from"].Value;
Transition transition = newTransistions.Find(trans => trans.From == fromState);
if (transition != null)
{
transition.To.Add(transitionXML.Attributes["to"].Value);
}
// If we could not find this state already then add it.
else
{
// save off the transistion (from first so we can look up state progression.
newTransistions.Add(new Transition
{
From = transitionXML.Attributes["from"].Value,
To = new List<string> { transitionXML.Attributes["to"].Value }
});
}
}
// Save off this transition so we don't do it again if it is needed.
_allTransistions.Add(workItemType, newTransistions);
return newTransistions;
}
As the code shown below, I want to get value from the OracleParameter object. Its datatype is datetime.
...
Dim cmd As New OracleCommand("stored_proc_name", cnObject)
cmd.Parameters.Add("tran_date_out", OracleDbType.Date, ParameterDirection.Output)
...
cmd.ExecuteNonQuery()
...
Dim tranDate As Date
tranDate = cmd.Parameters("tran_date_out").Value
When I assign value to tranDate variable, I get an error. But if I code as below, I get only the date.
tranDate = CDate(cmd.Parameters("tran_date_out").Value.ToString)
So how can I get the value both date and time to tranDate variable?
off the top of my head, the OracleParameter.Value, when an out parameter, is assigned to a strange Oracle boxed type. It seems like a completely terrible design or Oracle's part... but instead of returning String, you will get OracleString, etc.
Each of the Oracle types has a .Value that has the system type, but of course they don't all implement a common interface to expose this, so what I did was basically write a method to unbox the types:
/// <summary>
/// The need for this method is highly annoying.
/// When Oracle sets its output parameters, the OracleParameter.Value property
/// is set to an internal Oracle type, not its equivelant System type.
/// For example, strings are returned as OracleString, DBNull is returned
/// as OracleNull, blobs are returned as OracleBinary, etc...
/// So these Oracle types need unboxed back to their normal system types.
/// </summary>
/// <param name="oracleType">Oracle type to unbox.</param>
/// <returns></returns>
internal static object UnBoxOracleType(object oracleType)
{
if (oracleType == null)
return null;
Type T = oracleType.GetType();
if (T == typeof(OracleString))
{
if (((OracleString)oracleType).IsNull)
return null;
return ((OracleString)oracleType).Value;
}
else if (T == typeof(OracleDecimal))
{
if (((OracleDecimal)oracleType).IsNull)
return null;
return ((OracleDecimal)oracleType).Value;
}
else if (T == typeof(OracleBinary))
{
if (((OracleBinary)oracleType).IsNull)
return null;
return ((OracleBinary)oracleType).Value;
}
else if (T == typeof(OracleBlob))
{
if (((OracleBlob)oracleType).IsNull)
return null;
return ((OracleBlob)oracleType).Value;
}
else if (T == typeof(OracleDate))
{
if (((OracleDate)oracleType).IsNull)
return null;
return ((OracleDate)oracleType).Value;
}
else if (T == typeof(OracleTimeStamp))
{
if (((OracleTimeStamp)oracleType).IsNull)
return null;
return ((OracleTimeStamp)oracleType).Value;
}
else // not sure how to handle these.
return oracleType;
}
This probably isn't the cleanest solution, but... it was quick and dirty,a nd does work for me.
Just pass the OracleParameter.Value into this method.
Actually, I might have only 1/2 read your question before answering. I think Oracle's Date type only contains the date not the time.
The oracle type Timestamp has both the date and time.
Hope that helps! :)
I have not tested heavily, but here is a less verbose version of CodingWithSpike's answer using reflection...
public static object UnBoxOracleType(object oracleType) {
if(oracleType==null) {
return null;
}
if((bool)oracleType.GetType().GetProperty("IsNull").GetValue(oracleType)) {
return null;
}
return oracleType.GetType().GetProperty("Value").GetValue(oracleType);
}
Again you are passing OracleParameter.Value into this method.
Or for a more typesafe version you could do this:
public static object GetValue(OracleParameter param) {
if(param == null || param.Value==null) {
return null;
}
var oracleType=param.Value;
if((bool)oracleType.GetType().GetProperty("IsNull").GetValue(oracleType)) {
return null;
}
return oracleType.GetType().GetProperty("Value").GetValue(oracleType);
}
In this case you would pass the oracle parameter itself in to get the value back. This could also be implemented as an extension method if you so desired...