I need to pull the value of a variable in a child package to the parent package. I can not get this to work.
I can set variables from parent to child using package configurations, but I cant find a way to get child value into parent. I tried using same process I used to set value from parent in child but it does not work.
The posted possible solution from another topic did not solve the problem it just stated it may not be possible. The post was from 2013 and a lot of things change, I wanted to see if this is possible now (without saving a value to an external table or anything like that).
This child package is being used in a lot of spots, many of which would not have the parent variable I am trying to set (it would not exist in the parent variable). So the standard script in the post above would not work. I was hoping for a simple return variable value.
Using the above post as a starting point I updated the C# code to check to see if the variable I am trying to set in the parent package exists first (because it would not always be there), then if so set it.
Below is the code I came up with
// have to do this FIRST so you can access variable without passing it into the script task from SSIS tool box
// Populate collection of variables.
//This will include parent package variables.
Variables vars = null;
Dts.VariableDispenser.GetVariables(ref vars);
// checks if this variable exists, and if so then will set it to the value of the child variable
if (Dts.VariableDispenser.Contains("ParentVar") == true)
{
//MessageBox.Show("ParentVariableExists");
// Lock the to and from variables.
// parent variable
Dts.VariableDispenser.LockForWrite("User::ParentVar");
// child variable
Dts.VariableDispenser.LockForRead("User::ChildVar");
// Apparently need to call GetVariables again after locking them.
// Not sure why - perhaps to get a clean post-lock set of values.
Dts.VariableDispenser.GetVariables(ref vars);
// parentvar = childvar
vars["User::ParentVar"].Value = vars["User::ChildVar"].Value;
vars.Unlock();
}
You can put the variable in the parent package, and let the child package modify it.
Another sure-fire way is to populate a table in the child package and read the table in the parent package.
Related
I have created a child SSIS package that executes according to the "ProcessName" variable value that is specified initially. Now, I wish to create a parent package such that I can execute 4 child package tasks with different ProcessName values passed in to be executed in parallel. How can I maintain my child package and pass in different values to each of the 4 execute packages task such that the ProcessNames variable values are different for each of them? I am new to SSIS and would deeply appreciate if someone could advice or give a direction on how I could go about doing so.
I would see this as a pattern like the following
The "trick" here is that within each Sequence Container, SEQC, I need to define my variable that holds my parameter value. That variable needs to be scoped to the container - otherwise, there is only one SSIS variable and the 4 processes that attempt to initialize that value will be in conflict.
In the SSIS Variables menu, there is a Move Variable icon (second one listed)
Here you can see that I have ParameterValue defined in both "SEQC Opt 1a" and "SEQC Opt 1b" and they're initialized with different values.
The first step within the Sequence container is an Execute SQL Task where I pull back the intended parameter value. Maybe that is not needed in your case but it can be helpful to have a repository of run-time values. In the case of 1b, this is much more what my execution pattern looks like. I have a query that pulls back any packages to be run within the scope of this container and the starting value. e.g.
ContainerName|PackageName|StartingValue
SEQC Opt 1a |Child0.dtsx|100
SEQC Opt 1a |Child1.dtsx|200
SEQC Opt 1a |Child2.dtsx|300
SEQC Opt 1b |Child5.dtsx|600
SEQC Opt 1b |Child6.dtsx|700
SEQC Opt 1b |Child7.dtsx|800
This table pattern allows me to dynamically run packages in both parallel and in serial. Assuming Child7 and Child2 in the above set are very slow but the other 4 packages are relatively fast. The fast ones would start up, do their work and complete and the next runs. There are limits to how many parallel operations can fire at once so you can't scale infinitely across processes so a balance of serial and parallel operations makes sense.
Once you have your pattern working for one sequence container: copy, paste, rename and assuming you lookup in a table based on the task name as I show above, it's ready to go.
NOTE for everyone reading this answer: This answer is not full/complete with examples/full steps. From comment above I am posting this now so requestor can see it and get started.
This was from notes I wrote myself a long while back on how to do this for myself. I am posting it as answer as it is helpful and too large to post as comment. Plus I have not rewritten anything in what wrote for myself and what I am posting.
Currently I can not find my full code yet to post full details/steps. If/when I do I will post here, but this should be good details on what/how to do it. Plus this gives info on how to handle child package error trapping as well.
-- my notes I saved for myself posting as answer:
Steps for creating child packages:
Create any variables needed in the child package
Create the coorisponding variable name in the parent package (the name doesnot have to be the same, and maybe want to name it something to identify it as a child package variable)
Child Package:
Need to set up: Package Configurations
a. Right click on package and click Package Paramaters
b. Click the checkox to Enable Package configurations
Click Add and set the paramaters:
a. Configuration Type: Pareknt Package variable
b. Specify the configuration setting directly: Put the parent variable name in here that the child package is going to access
c. Click "Next"
d. In "Objects" window scroll down to the variable you are setting from the parent variable name you selected above and click the "Value" option under Properties for that variable name
e. Click "Next"
f. Under Configuration Name: Set a detailed name for what this variable is/does.
Error Handling (NOTE: This is not required but you wont capture the child error messages if you dont do this):
a. Go to Event Handlers Tab
b. Under drop down (on top right) select OnError
c. Add a Scrit Task
d. Pass as read only variables:
System::ErrorDescription
System::SourceName
System::PackageName
e. Copy/paste the code below into the script task uin the Main() function.
----- this is for the error handling
public void Main()
{
// build our the error message
string ErrorMessageToPassToParent = "Package Name: " + Dts.Variables["System::PackageName"].Value.ToString() + Environment.NewLine + Environment.NewLine +
"Step Failed On: " + Dts.Variables["System::SourceName"].Value.ToString() + Environment.NewLine + Environment.NewLine +
"Error Description: " + Dts.Variables["System::ErrorDescription"].Value.ToString();
// have to do this FIRST so you can access variable without passing it into the script task from SSIS tool box
// Populate collection of variables. This will include parent package variables.
Variables vars = null;
Dts.VariableDispenser.GetVariables(ref vars);
// checks if this variable exists in parent first, and if so then will set it to the value of the child variable
// (do this so if parent package does not have the variable it will not error out when trying to set a non-existant varaible)
if (Dts.VariableDispenser.Contains("OnError_ErrorDescription_FromChild") == true)
{
// Lock the to and from variables.
// parent variable
Dts.VariableDispenser.LockForWrite("User::OnError_ErrorDescription_FromChild");
// Need to call GetVariables again after locking them. Not sure why - perhaps to get a clean post-lock set of values.
Dts.VariableDispenser.GetVariables(ref vars);
// Set parentvar = childvar
vars["User::OnError_ErrorDescription_FromChild"].Value = ErrorMessageToPassToParent;
vars.Unlock();
}
Dts.TaskResult = (int)ScriptResults.Success;
}
Parent Package:
Add this variable to propertly capture the child error messages (not required but you wont capture chidl error messages if you dont):
variable: OnError_ErrorDescription_FromChild
Error Handling(NOTE: This is not required but you wont capture the child error messages if you dont do this):
a. Go to Event Handlers Tab
b. Under drop down (on top right) select OnError
c. Add a Scrit Task
d. Pass as read only variables:
User::OnError_ErrorDescription_FromChild
e. Copy/paste the code below into the script task uin the Main() function.
----- this is for the error handling
public void Main()
{
// get the varaible from the parent package for the error
string ErrorFromChildPackage = Dts.Variables["User::OnError_ErrorDescription_FromChild"].Value.ToString();
// do a check if the value is empty or not (so we knwo if the error came from the child package or the occurent in the parent package itself
if (ErrorFromChildPackage.Length > 0)
{
// Then raise the error that was created in the child package
Dts.Events.FireError(0, "Capture Error From Child Package Failure",
ErrorFromChildPackage
, String.Empty, 0);
//Dts.TaskResult = (int)ScriptResults.Failure;
} // end if the error length of variable is > 0
Dts.TaskResult = (int)ScriptResults.Success;
}
NOTES:
For error handling:
a. The child package error handling is written so it wont fail if the variables or error handling does not exist in parent package.
b. If you include the error handling (and variable) in the parent package it MUST exist in the child package though.
I have constructed a BST in as3 which contains a function to delete a node from the tree which has the provided value.
Here is the code. Here pull actually means "delete". I am only giving the problematic code.
public function pull(k:int)
{
//find the node in BST
t = search(k);
//if the node was found with value k
if (t)
{
//the node did not have any children
if (t.none())
{
//simply set it to null
t = null;
}
else if (t.one())
{
}
else if (t.two())
{
}
}
}
I have already inserted two values in tree 12 and 10.
the tree is like this
12
/
10
then I have called the function
pull(10);
but when i try to trace(bst.root.leftChild) it still gives the output as
[Object Node]
I have no idea how to fix it.
I'm not familiar with AS3, but I will attempt to answer this question.
Basically what you are doing when you do t = search(k) is that the search function returns a copy of the reference in t, in other words, t is set to refer to result of search(k).
When you do t = null, you are doing nothing but removing that connection between t and the tree node which you want to delete. But that does not delete the node. It just sets t to refer to null.
Coming from C background, I will suggest 2 ways to solve it:
Use something like a pointer to pointer (if it exists in AS3, sorry I dont know about it).
Use the parent node of the desired node to delete it. For example if you want to delete a node b which is the left child of a, doing a.left = null will delete the desired node as it effectively acts as a pointer to pointer.
I apologize for any factual mistakes in my answer, please correct me if I am wrong.
Setting an object to null is not an efficient way to delete it on the fly, in fact it will most likely keep existing for a while until it is eventually GC. But of course this can only happen if EVERY SINGLE reference of that object are nullified. Having one variable nullified will have no effect if that object is still referenced somewhere else.
So even when nullifying all references the object will keep existing for a while so the best way is to implement a method that will set the object to inactive to it can be skipped. The after that you can start removing all references to it.
The simple fact that you are tracing "trace(bst.root.leftChild)" means that the variable "leftChild" still has a reference to the node object, if you don't nullify that one then the object will still exist. If you don't nullify all references to that object then the object will keep existing.
I was actually looking for a way to pass by reference in AS3 but then it seemed that adobe and lots of people's understanding of pass by reference is different from what I have been taught at the university. I was taught java was pass by value and C++ allowed pass by reference.
I'm not trying to argue what pass by value and reference are. I just want to explain why I'm using pass by object in the question...
Back to the question, I would like to do something like:
public function swapCard(cardA:Cards, cardB:Cards) {
var temp:Cards = cardA;
cardA = cardB;
cardB = temp;
}
...
swapCard(c1, c2);
EDIT: adding two examples on how I'm using the swapCard function
1) in the process of swaping a card between player1 and player2's hand
swapCard(player1.hand[s], player2.hand[t]);
2) in the process of swaping a card between player1's hand and deck
swapCard(player1.hand[s], player1.deck[rand]);
In C++, we only need to add a symbol before the parameters to make it work (and we call THIS pass by reference). But in AS3, cardA and cardB are just pointers to the formal parameters. Here in the function, changing the pointers does not do anything to the formal parameters :(
I have been searching for hours but I couldn't find a way to without knowing all the properties of the Cards.
If I have to change the properties of the cards one by one then maybe I should change swapCard to a static function in class Cards? (because I don't want to expose everything to another class) I'm not sure if this is a good practice either. This is like adding a swap_cars function into class Cars. If I let this happen, what will be next? Wash car, lend car, rent car... I really want to keep the Cards class clean and holds only the details of the card. Is there a possible way to do this properly in AS3?
The kind of swap function that you're trying to implement is not possible in AS3. The input parameters are references to the input objects but the references themselves are passed by value. This means that inside the function you can change the cardA and cardB but those changes will not be visible outside the function.
Edit: I added this portion after you edited your question with sample usage.
It seems like you're trying to swap two objects in 2 different arrays at given array positions in each - you can create a function for this in AS3 but not the way you attempted.
One possible implementation is to pass the arrays themselves and the positions that you're trying to exchange; something like this:
// Assumes arrays and indices are correct.
public function SwapCards(playerHand:Array, playerCardIndex:int,
playerDeck:Array, playerDeckIndex:int):void
{
var tempCard:Card = playerHand[playerHandIndex];
playerHand[playerHandIndex] = playerDeck[playerDeckIndex];
playerDeck[playerDeckIndex] = tempCard;
}
Note that you still exchange references and the arrays themselves are still passed by reference (and the array references are passed by value - you could, if you wanted, change the arrays to new arrays inside this function but you wouldn't see new arrays outside). However, because the array parameters refer to the same arrays inside and outside the function, you can make changes to the contents of the array (or other array properties) and those changes will be visible outside.
This solution is faster than cloning the card because that involves allocating memory for a new Card instance (which is expensive) and that temporary instance will also have to be freed by the garbage collector (which is also expensive).
You mentioned in a comment that you pass cards down to lower levels of code - if you don't have a back reference to the arrays (and the positions of the cards), you will not be able to easily swap cards - in AS3, all input parameters are copies (either the copy of the value for primitive types or the copy of the reference for complex objects - changes to the input parameters in a function will not be visible outside).
EDIT: renaming the function from clone to copyFrom as pointed out by aaron. Seems like clone is supposed to be used as objA = objB.clone()
At this point, I'm adding a copyFrom() function in the Cards class such that
var temp:Cards = new Cards(...);
var a:Cards = new Cards(...);
...
temp.copyFrom(a);
...
temp will be copying everything from a.
public function swapCard(cardA:Cards, cardB:Cards) {
var temp:Cards = new Cards();
temp.copyFrom(cardA);
cardA.copyFrom(cardB);
cardB.copyFrom(temp);
}
I will wait for a week or so to see if there are any other options
You have some good answers already, but based on the comments back-and-forth with me, here's my suggestion (I use "left" and "right" naming because it helps me visualize, but it doesn't matter):
function swapCard(leftCards:Array, leftCard:Card, rightCards:Array, rightCard:Card):void {
var leftIndex:int = leftCards.indexOf(leftCard);
var rightIndex:int = rightCards.indexOf(rightCard);
leftCards[leftIndex] = rightCard;
rightCards[rightIndex] = leftCard;
}
Now you can swap the cards in the two examples you posted like this:
swapCard(player1.hand, player1.hand[s], player2.hand, player2.hand[t]);
swapCard(player1.hand, player1.hand[s], player1.deck, player1.deck[rand]);
However, note that while this swaps the cards in the arrays, it does not swap direct references to the cards in those arrays. In other words:
var a:Card = player1.hand[0];
var b:Card = player2.hand[0];
swapCard(player1.hand, a, player2.hand, b);
// does not change the references a and b, they still refer to the same card
a == player2.hand[0];
a != player1.hand[0];
b == player1.hand[0];
b != player2.hand[0];
Typically, this sort of thing is handled by dispatching a "changed" event so that any code that cares about the state of a player's hand array will know to re-evaluate the state of the hand.
There's a deep misunderstanding going on here. The question is about object reference but the PO is not trying to swap any Object reference at all.
The problem comes from the fact that the PO does not understand the difference between variable and objects. He's trying to swap variable/object reference which is not dynamically possible of course. He wants with a function to make the variable holding a reference to Object A, swap its object reference with another variable. Since Objects can be passed around but not variables (since they are just holders (not pointers)) the task is not possible without a direct use of the given variable.
To resume:
variables are not Objects!
variables hold a reference to an object.
variables cannot be passed in function or referenced in functions because THEY ARE NOT OBJECTS.
I'm trying to create an SSIS package to process files from a directory that contains many years worth of files. The files are all named numerically, so to save processing everything, I want to pass SSIS a minimum number, and only enumerate files whose name (converted to a number) is higher than my minimum.
I've tried letting the ForEach File loop enumerate everything and then exclude files in a Script Task, but when dealing with hundreds of thousands of files, this is way too slow to be suitable.
The FileSpec property lets you specify a file mask to dictate which files you want in the collection, but I can't quite see how to specify an expression to make that work, as it's essentially a string match.
If there's an expression within the component somewhere which basically says Should I Enumerate? - Yes / No, that would be perfect. I've been experimenting with the below expression, but can't find a property to which to apply it.
(DT_I4)REPLACE( SUBSTRING(#[User::ActiveFilePath],FINDSTRING( #[User::ActiveFilePath], "\", 7 ) + 1 ,100),".txt","") > #[User::MinIndexId] ? "True" : "False"
Here is one way you can achieve this. You could use Expression Task combined with Foreach Loop Container to match the numerical values of the file names. Here is an example that illustrates how to do this. The sample uses SSIS 2012.
This may not be very efficient but it is one way of doing this.
Let's assume there is a folder with bunch of files named in the format YYYYMMDD. The folder contains files for the first day of every month since 1921 like 19210101, 19210201, 19210301 .... all the upto current month 20121101. That adds upto 1,103 files.
Let's say the requirement is only to loop through the files that were created since June 1948. That would mean the SSIS package has to loop through only the files greater than 19480601.
On the SSIS package, create the following three parameters. It is better to configure parameters for these because these values are configurable across environment.
ExtensionToMatch - This parameter of String data type will contain the extension that the package has to loop through. This will supplement the value to FileSpec variable that will be used on the Foreach Loop container.
FolderToEnumerate - This parameter of String data type will store the folder path that contains the files to loop through.
MinIndexId - this parameter of Int32 data type will contain the minimum numerical value above which the files should match the pattern.
Create the following four parameters that will help us loop through the files.
ActiveFilePath - This variable of String data type will hold the file name as the Foreach Loop container loops through each file in the folder. This variable is used in the expression of another variable. To avoid error, set it to a non-empty value, say 1.
FileCount - This is a dummy variable of Int32 data type will be used for this sample to illustrate the number of files that the Foreach Loop container will loop through.
FileSpec - This variable of String data type will hold the file pattern to loop through. Set the expression of this variable to below mentioned value. This expression will use the extension specified on the parameters. If there are no extensions, it will *.* to loop through all files.
"*" + (#[$Package::ExtensionToMatch] == "" ? ".*" : #[$Package::ExtensionToMatch])
ProcessThisFile - This variable of Boolean data type will evaluate whether a particular file matches the criteria or not.
Configure the package as shown below. Foreach loop container will loop through all the files matching the pattern specified on the FileSpec variable. An expression specified on the Expression Task will evaluate during runtime and will populate the variable ProcessThisFile. The variable will then be used on the Precedence constraint to determine whether to process the file or not.
The script task within the Foreach loop container will increment the counter of variable FileCount by 1 for each file that successfully matches the expression.
The script task outside the Foreach loop will simply display how many files were looped through by the Foreach loop container.
Configure the Foreach loop container to loop through the folder using the parameter and the files using the variable.
Store the file name in variable ActiveFilePath as the loop passes through each file.
On the Expression task, set the expression to the following value. The expression will convert the file name without the extension to a number and then will check if it evaluates to greater than the given number in the parameter MinIndexId
#[User::ProcessThisFile] = (DT_BOOL)((DT_I4)(REPLACE(#[User::ActiveFilePath], #[User::FileSpec] ,"")) > #[$Package::MinIndexId] ? 1: 0)
Right-click on the Precedence constraint and configure it to use the variable ProcessThisFile on the expression. This tells the package to process the file only if it matches the condition set on the expression task.
#[User::ProcessThisFile]
On the first script task, I have the variable User::FileCount set to the ReadWriteVariables and the following C# code within the script task. This increments the counter for file that successfully matches the condition.
public void Main()
{
Dts.Variables["User::FileCount"].Value = Convert.ToInt32(Dts.Variables["User::FileCount"].Value) + 1;
Dts.TaskResult = (int)ScriptResults.Success;
}
On the second script task, I have the variable User::FileCount set to the ReadOnlyVariables and the following C# code within the script task. This simply outputs the total number of files that were processed.
public void Main()
{
MessageBox.Show(String.Format("Total files looped through: {0}", Dts.Variables["User::FileCount"].Value));
Dts.TaskResult = (int)ScriptResults.Success;
}
When the package is executed with MinIndexId set to 1948061 (excluding this), it outputs the value 773.
When the package is executed with MinIndexId set to 20111201 (excluding this), it outputs the value 11.
Hope that helps.
From investigating how the ForEach loop works in SSIS (with a view to creating my own to solve the issue) it seems that the way it works (as far as I could see anyway) is to enumerate the file collection first, before any mask is specified. It's hard to tell exactly what's going on without seeing the underlying code for the ForEach loop but it seems to be doing it this way, resulting in slow performance when dealing with over 100k files.
While #Siva's solution is fantastically detailed and definitely an improvement over my initial approach, it is essentially just the same process, except using an Expression Task to test the filename, rather than a Script Task (this does seem to offer some improvement).
So, I decided to take a totally different approach and rather than use a file-based ForEach loop, enumerate the collection myself in a Script Task, apply my filtering logic, and then iterate over the remaining results. This is what I did:
In my Script Task, I use the asynchronous DirectoryInfo.EnumerateFiles method, which is the recommended approach for large file collections, as it allows streaming, rather than having to wait for the entire collection to be created before applying any logic.
Here's the code:
public void Main()
{
string sourceDir = Dts.Variables["SourceDirectory"].Value.ToString();
int minJobId = (int)Dts.Variables["MinIndexId"].Value;
//Enumerate file collection (using Enumerate Files to allow us to start processing immediately
List<string> activeFiles = new List<string>();
System.Threading.Tasks.Task listTask = System.Threading.Tasks.Task.Factory.StartNew(() =>
{
DirectoryInfo dir = new DirectoryInfo(sourceDir);
foreach (FileInfo f in dir.EnumerateFiles("*.txt"))
{
FileInfo file = f;
string filePath = file.FullName;
string fileName = filePath.Substring(filePath.LastIndexOf("\\") + 1);
int jobId = Convert.ToInt32(fileName.Substring(0, fileName.IndexOf(".txt")));
if (jobId > minJobId)
activeFiles.Add(filePath);
}
});
//Wait here for completion
System.Threading.Tasks.Task.WaitAll(new System.Threading.Tasks.Task[] { listTask });
Dts.Variables["ActiveFilenames"].Value = activeFiles;
Dts.TaskResult = (int)ScriptResults.Success;
}
So, I enumerate the collection, applying my logic as files are discovered and immediately adding the file path to my list for output. Once complete, I then assign this to an SSIS Object variable named ActiveFilenames which I'll use as the collection for my ForEach loop.
I configured the ForEach loop as a ForEach From Variable Enumerator, which now iterates over a much smaller collection (Post-filtered List<string> compared to what I can only assume was an unfiltered List<FileInfo> or something similar in SSIS' built-in ForEach File Enumerator.
So the tasks inside my loop can just be dedicated to processing the data, since it has already been filtered before hitting the loop. Although it doesn't seem to be doing much different to either my initial package or Siva's example, in production (for this particular case, anyway) it seems like filtering the collection and enumerating asynchronously provides a massive boost over using the built in ForEach File Enumerator.
I'm going to continue investigating the ForEach loop container and see if I can replicate this logic in a custom component. If I get this working I'll post a link in the comments.
The best you can do is use FileSpec to specify a mask, as you said. You could include at least some specs in it, like files starting with "201" for 2010, 2011 and 2012. Then, in some other task, you could filter out those you don't want to process (for instance, 2010).
I have a fairly straightforward SSIS package where I can't sucessfully pass the value of a package-scoped variable from the Control Flow to a Data Flow task. Consider the below diagram:
The Execute SQL task gets values from a list of "machines". This is used to control a ForEach Loop Container, which works very well. Next a script task performs some math and assigns a single number to a package scoped variable (integer type). I have added message boxes that pop up during the loop so that I can verify that the value of this variable is being set properly.
The last icon is a data flow where I want to use the variable value. I have a simple script task that contains just a message box showing me the current value of this same variable. Every time, the variable is the value that I initially set in the designer (BIDS). Therefore, the value is not being "passed" to the data flow. I have verified multiple times that the names of the variables are correct (including case sensitive values).
This should be pretty simple, and I am getting frustrated with this issue. I would greatly appreciate and suggestions or comments. Thank you!
How are you setting the package variable from your script task? It should look like this (c#):
DTS.Variables["testVariable"].Value = "some value";
Then to test it from the script component in your dataflow task:
public override void PostExecute()
{
base.PostExecute();
MessageBox.Show(Variables.testVariable, "test");
}
I did this in a test package and it worked fine.
EDIT
Also make sure that you added the variable to the ReadWriteVariables section of the properties for the script tasks.