Scenario: How to delete files created a number of days before today. The files will have the date appended to the file name and we will not check the file properties to decide the file age. The file name would follow the naming convention: File_mmddyyyy.txt
This can be achieved very easily in SSIS. Create an integer variable to store the value stating how old files do you wish to delete. Suppose you wish to delete all files older than 3 days, the variable would have the value 3. I name this variable intFileMaxAge. Make this variable configurable so that it can be changed as and when required.
Next I show the layout of the package.
The Foreach Loop Container is configured to pick the files from a particular folder(you should make this connection configurable) and the “Retrieve file name” property is set to “Name and extension”. Refer fig. 2
Next we need to save the file name for each iteration to a string variable strFileName. For this go to the Variable Mappings tab and select the variable strFileName from the drop down box and set the index to zero. Refer fig. 3
Once the above is done put a script task in the Foreach Loop Container. Do not make any changes to the script task. It is just there so that we can have Precedence Constraint before the File system task to control the flow. We need the File System Task to be triggered only when the condition is met i.e. files created before certain days (Refer fig. 1). Double click the precedence and set the Evaluation operation to Expression. In the Expression put the below expression:
DATEDIFF("dd",(DT_Date)(SUBSTRING(@[User::strFileName],6,2) + "-" + SUBSTRING(@[User::strFileName],8,2) + "-" + SUBSTRING(@[User::strFileName],10,4)),GETDATE()) > @[User::intFileMaxAge]
The above expression extracts the date part from the file name and converts it to date type. Once that’s done it gets the difference of the between the file date and today’s date. After this the expression checks whether the difference is greater than the value specified in the variable intFileMaxAge.
If the above expression will be evaluated to true the control will go to the File Sytem Task.
Setting up the File System Task. (refer fig. 4) The operation is set to Delete file as we need to delete files. Set the IsSourcePathVariable to False as I create a connection to connect to the file and use expression to modify the connection at run time.
NOTE: During development set the variable strFileName value to File_mmddyyyy.txt or else the expression will not evaluate.
In the Connection Managers select the connection manager configured above(refer fig. 4) go to its properties and in the expression set connection string to the following expression:
Where the variable strFolderPath contains the folder in which the files are placed. Again make this configurable.
That completes the package.
Update: The file format File_mmddyyyy.txt means that the file name will have leading zeros in case the date or month is of single digit. So a valid file name would be File_02182010.txt or File_10042010.txt. In case the file is File_222010 it would be an illegal file and the package would fail and we need to do error handling accordingly.
The expression has been modified to incorporate some validation not all.
LEN(@[User::strFileName]) == 17&& (DT_I8)SUBSTRING(@[User::strFileName],6,2) < 13 && (DT_I8)SUBSTRING(@[User::strFileName],8,2) < 32 && DATEDIFF("dd",(DT_Date)(SUBSTRING(@[User::strFileName],6,2) + "-"+SUBSTRING(@[User::strFileName],8,2) + "-" + SUBSTRING(@[User::strFileName],10,4)),GETDATE()) > @[User::intFileMaxAge]
Thanks Siddharth for pointing this out.