How do I cast an object without re-assigning it to another variable in VB.NET? - vb.net

I have the following code (PointLine and CalculatedLine both inherit Line):
For Each line As Lines.Line In lines
''Since both Point and Calculated lines are stored in the same list in the XML files,
''we need to force them back to their original type before using them
Select Case line.GetType()
Case GetType(Lines.PointLine)
line = DirectCast(line, Lines.PointLine)
line.init()''ERROR:'init' is not a member of 'PerformanceValidation.EngineValidation.Limits.Components.Lines.Line'
myLimitSeries.Add(line.series)
Case GetType(Lines.CalculatedLine)
line = DirectCast(line, Lines.CalculatedLine)
line.init(dataTable)''ERROR:'init' is not a member of 'PerformanceValidation.EngineValidation.Limits.Components.Lines.Line'
myLimitSeries.Add(line.series)
End Select
Next
The editor complains about line not being of type PointLine/CalculatedLine when i call line.init().
It's important that the original object be casted to either PointLine or CalculatedLine because I "initialize" them to contain calculated information that will be used later on. So basically, I don't want to create a new variable of type PointLine or CalculatedLine to act as a container for the casted Line.
I tried creating a new line of the appropriate type (exactly as I said I didn't want to above) and deleting the original line and adding the new one to the list but of course, it complains about the underlying list being modified.
Is there a way I can treat a Line as either a PointLine or CalculatedLine temporarily without affecting the list?
Thanks!

You don't need to create a new instance but you need to have a second variable of the right type for the reference. I don't understand when you say "delete", when you cast, you don't delete the instance since both variable are pointing at the same instance.
For Each line As Lines.Line In lines
Select Case line.GetType()
Case GetType(Lines.PointLine)
Dim linePoint As Lines.PointLine = DirectCast(line, Lines.PointLine)
linePoint.init()
myLimitSeries.Add(line.series)
Case GetType(Lines.CalculatedLine)
Dim lineCalculated As Lines.CalculatedLine = DirectCast(line, Lines.CalculatedLine)
lineCalculated.init(dataTable)
myLimitSeries.Add(line.series)
End Select
Next
No new instance are created here.
If you only call one function, you could always do.
For Each line As Lines.Line In lines
Select Case line.GetType()
Case GetType(Lines.PointLine)
DirectCast(line, Lines.PointLine).init()
myLimitSeries.Add(line.series)
Case GetType(Lines.CalculatedLine)
DirectCast(line, Lines.CalculatedLine).init(dataTable)
myLimitSeries.Add(line.series)
End Select
Next

You cannot re-type an item in a collection, because the type is set for the whole collection (in your example it's end of line 1).
I'd take a decision, whether the source data are in correct/required format or not. If you're not happy with the source format, I'd fix it there. If you need the source as is, I'd treat the lines in a layer above, but it would certainly require another collections.
Either you could convert one type of lines to another and put them into one collection or you could have one collection with some IDs and type, and two other collections for each type (you can probably use the source collections then).

Related

Execute SQL Task -Full Result Set Datatype Mismatch Error

I am creating an SSIS package which has an execute SQL task and it passes result set variable to a for each loop container.
My Sql Query is:
Select distinct code from house where active=1 and campus='W'
I want the execute sql task to run this query and assign its results to a variable which is passed to a for each loop container which should loop through all the values in the result set.
But my execute sql task fails with error:
The type of the value (DBNull) being assigned to variable
"User::house" differs from the current variable type (String)
Now i have done my research and i have tried assigning the variable datatype Object but did not work. I tried using cast in my sql query and that also did not work.
Since my query returns multiple rows and one column, i am not sure how i can assign a datatype to the whole query?
Sample:
Code
AR
BN
CN
It sounds like you have a variety of issues in here.
Result Set
The first is in your Execute SQL Task and the need for agreement between the Result Set specification and the data type of the Variable(s) specified in the Result Set tab. If you specify Full Resultset, then the receiving object must be of type System::Object and you will only have 1 result set. The type of Connection Manager (ODBC/OLE/ADO) used will determine how you specify it but it's infinitely searchable on these fine forums.
The other two options are Single Row and XML. In 13 years of working with SSIS, I've never had cause to specify XML. That leaves us with Single Row. For a Single Row Result Set, you need to provide a variable for each column returned and it needs to be correctly typed.
To correct your issue, you need to declare a second variable. I usually call my rsObject (record set object) and then specify the data type as System.Object.
For Each Loop Container
Your For Each Loop Container will then be set with an Enumerator of "Foreach ADO Enumerator" and then the ADO object source variable will become "User::rsObject"
In the Variable Mappings, you'll specify your variable User::house to index 0.
Testing
Given a sample set of source source data, you can verify that you have your Execute SQL Task correctly assigning a result set to our object and the Foreach Loop Container is properly populating our variable.
SELECT DISTINCT
code
FROM
(
VALUES
('ABC', 1, 'w')
, ('BCD', 1, 'w')
, ('CDE', 0, 'w')
, ('DEF', 1, 'w')
, ('EFG', 1, 'x')
) house(code, active, campus)
WHERE
active = 1
AND campus = 'w';
If you change the value of campus from w to something that doesn't exist, like f then things will continue to work.
However, the error you're receiving can only be generated if the code is a NULL
Add one more entry to the VALUES collection like
, (NULL, 1, 'w')
and when the For Each Loop Container hits that value, you will encounter the error you indicate
The type of the value (DBNull) being assigned to variable "User::house" differs from the current variable type (String)
Now what?
SSIS variables cannot change their data type, unless they're of type Object (but that's not the solution here). The "problem" is that you cannot store a NULL value in an SSIS variable (unless it's of type object). Therefore you need to either exclude the rows that return a NULL (AND code IS NOT NULL) or you need to cast the NULL into sentinel/placeholder value as a substitute (SELECT DISTINCT ISNULL(code, '') AS code). If an empty string is a valid value, then you need to find something that isn't - "billinkcisthegreatestever10123432" is unlikely to exist in your set of codes but that might be a bit excessive.
Finally, think about renaming your SSIS variable from house to code. You might be able to keep things straight but some day you'll hand this code over to someone else for maintenance and you don't want to confuse them.
A picturesque answer https://stackoverflow.com/a/13976990/181965
the variable "User::house" is string , so , did you use it in result set?
you need declare son "object" var for result set
result set
then declare a string variable for every single Code from your result
For Each Loop Container
good luck

Get Text Symbol Programmatically With ID

Is there any way of programmatically getting the value of a Text Symbol at runtime?
The scenario is that I have a simple report that calls a function module. I receive an exported parameter in variable LV_MSG of type CHAR1. This indicates a certain status message created in the program, for instance F (Fail), X (Match) or E (Error). I currently use a CASE statement to switch on LV_MSG and fill another variable with a short description of the message. These descriptions are maintained as text symbols that I retrieve at compile time with text-MS# where # is the same as the possible returns of LV_MSG, for instance text-MSX has the value "Exact Match Found".
Now it seems to me that the entire CASE statement is unnecessary as I could just assign to my description variable the value of the text symbol with ID 'MS' + LV_MSG (pseudocode, would use CONCATENATE). Now my issue is how I can find a text symbol based on the String representation of its ID at runtime. Is this even possible?
If it is, my code would look cleaner and I wouldn't have to update my actual code when new messages are added in the function module, as I would simply have to add a new text symbol. But would this approach be any faster or would it in fact degrade the report's performance?
Personally, I would probably define a domain and use the fixed values of the domain to represent the values. This way, you would even get around the string concatenation. You can use the function module DD_DOMVALUE_TEXT_GET to easily access the language-dependent text of a domain value.
To access the text elements of a program, use a function module like READ_TEXT_ELEMENTS.
Be aware that generic programming like this will definitely slow down your program. Whether it would make your code look cleaner is in the eye of the beholder - if the values change rarely, I don't see why a simple CASE statement should be inferior to some generic text access.
Hope I understand you correctly but here goes. This is possible with a little trickery, all the text symbols in a report are defined as variables in the program (with the name text-abc where abc is the text ID). So you can use the following:
data: lt_all_text type standard table of textpool with default key,
lsr_text type ref to textpool.
"Load texts - you will only want to do this once
read textpool sy-repid into lt_all_text language sy-langu.
sort lt_all_Text by entry.
"Find a text, the field KEY is the text ID without TEXT-
read table lt_all_text with key entry = i_wanted_text
reference into lsr_text binary search.
If you want the address you can add:
field-symbols: <l_text> type any.
data l_name type string.
data lr_address type ref to data.
concatenate 'TEXT-' lsr_text->key into l_name.
assign (l_name) to <l_text>.
if sy-subrc = 0.
get reference of <l_text> into lr_address.
endif.
As vwegert pointed out this is probably not the best solution, for error handling rather use message classes or exception objects. This is useful in other cases though so now you know how.

How to use LOOP AT itab INTO <fieldsymbol>

As I rarely loop into a field symbol, I often forget to use ASSIGNING instead of INTO which will promptly cause an abend. Is there a valid use of INTO with <fieldsymbol> or is this something that the syntax checker really ought to catch?
LOOP...INTO is perfectly valid but it will work differently. LOOP...INTO transports the values to the structure provided but ASSIGNING assigns the field symbol to the actual table rows.
The only difference is if you are going to change the table contents. See the following:
* Changes all entries in the CARRID column of lt_flights to 50.
LOOP AT lt_flights ASSIGNING <flight>.
<flight>-carrid = 50.
ENDLOOP.
* Does not change the entries in lt_flights (MODIFY...FROM would be required).
ASSIGN <flight> TO ls_flight.
LOOP AT lt_flights INTO <flight>.
<flight>-carrid = 50.
ENDLOOP.
LOOP...INTO with a field symbol would be useless unless you had some kind of dynamic programming requirement.
It is valid when <fieldsymbol> was previously assigned to a structure which has the type of the lines of the table you loop over.
It is a perfectly valid statement:
APPEND INITIAL LINE TO lt_foo ASSIGNING <ls_foo>.
READ TABLE lt_bar INTO <ls_foo> INDEX 1.
A field symbol just takes the place of a variable - at almost any point - so the syntax check can't flag this as invalid. It might issue a warning, though...

How to comment on MATLAB variables

When I´m using MATLAB, sometimes I feel the need to make comments on some variables. I would like to save these comments inside these variables. So when I have to work with many variables in the workspace, and I forget the context of some of these variables I could read the comments I put in every one of them. So I would like to comment variables and keep the comments inside of them.
While I'm of the opinion that the best (and easiest) approach would be to make your variables self-documenting by giving them descriptive names, there is actually a way for you to do what you want using the object-oriented aspects of MATLAB. Specifically, you can create a new class which subclasses a built-in class so that it has an additional property describing the variable.
In fact, there is an example in the documentation that does exactly what you want. It creates a new class ExtendDouble that behaves just like a double except that it has a DataString property attached to it which describes the data in the variable. Using this subclass, you can do things like the following:
N = ExtendDouble(10,'The number of data points')
N =
The number of data points
10
and N could be used in expressions just as any double value would. Using this example subclass as a template, you could create "commented" versions of other built-in numeric classes, with the exception of those you are not allowed to subclass (char, cell, struct, and function_handle).
Of course, it should be noted that instead of using the ExtendDouble class like I did in the above example, I could instead define my variable like so:
nDataPoints = 10;
which makes the variable self-documenting, albeit with a little more typing needed. ;)
How about declaring another variable for your comments?
example:
\>> num = 5;
\>> numc = 'This is a number that contains 5';
\>> whos
...
This is my first post in StackOverflow. Thanks.
A convenient way to solve this is to have a function that does the storing and displaying of comments for you, i.e. something like the function below that will pop open a dialog box if you call it with comments('myVar') to allow you to enter new (or read/update previous) comments to variable (or function, or co-worker) labeled myVar.
Note that the comments will not be available in your next Matlab session. To make this happen, you have to add save/load functionality to comments (i.e. every time you change anything, you write to a file, and any time you start the function and database is empty, you load the file if possible).
function comments(name)
%COMMENTS stores comments for a matlab session
%
% comments(name) adds or updates a comment stored with the label "name"
%
% comments prints all the current comments
%# database is a n-by-2 cell array with {label, comment}
persistent database
%# check input and decide what to do
if nargin < 1 || isempty(name)
printDatabase;
else
updateDatabase;
end
function printDatabase
%# prints the database
if isempty(database)
fprintf('no comments stored yet\n')
else
for i=1:size(database,1)
fprintf('%20s : %s\n',database{i,1},database{i,2});
end
end
end
function updateDatabase
%# updates the database
%# check whether there is already a comment
if size(database,1) > 0 && any(strcmp(name,database(:,1)))
idx = strcmp(name,database(:,1));
comment = database(idx,2);
else
idx = size(database,1)+1;
comment = {''};
end
%# ask for new/updated comment
comment = inputdlg(sprintf('please enter comment for %s',name),'add comment',...
5,comment);
if ~isempty(comment)
database{idx,1} = name;
database(idx,2) = comment;
end
end
end
Always always always keep the Matlab editor open with a script documenting what you do. That is, variable assignments and calculations.
Only exceptions are very short sessions where you want to experiment. Once you have something -- add it to the file (It's also easier to cut and paste when you can see your entire history).
This way you can always start over. Just clear all and rerun the script. You never have random temporaries floating around in your workspace.
Eventually, when you are finished, you will also have something that is close to 'deliverable'.
Have you thought of using structures (or cells, although structures would require extra memory use)?
'>> dataset1.numerical=5;
'>> dataset1.comment='This is the dataset that contains 5';
dataset1 =
numerical: 5
comment: 'This is the dataset that contains 5'

QTP, access to QC field by label

I want to update a custom user field in QC using the Label of field instead of the name
At the moment we are doing it this way
Set currentRun = QCUtil.CurrentRun
currentRun.Field("RN_USER_03") = 1
currentRun.Post
But I would like to do it this way
Set currentRun = QCUtil.CurrentRun
currentRun.Field("Data Rows Passed") = 4
currentRun.Post
But I can't find the method to do it with.
Any Ideas?
Implying all labels are unique (which I doubt..):
You could create a function which accepts a label, searches in QC's tables that define customized fields for the correct field definition, and returns the field name. Then use the function's result value as the indexed property's index.
Suppose that function would be called "GetNameOfLabel", then the Caller's code would look like:
Set currentRun = QCUtil.CurrentRun
currentRun.Field(GetNameOfLabel ("Data Rows Passed")) = 1
currentRun.Post
Of course, the function would not really be trivial, but easy enough after some digging in the QC data model and finding an efficient way to fetch the name from the DB via SQL.
Or, the function could look up the name in an array, or a dictionary, then you would have to maintain that dictionary, but you would not have to go to the database for each lookup.
Disadventages:
Scripts with the wrong label might be harder to be debug
If labels are not unique, it might be real "fun" to debug
If looking up on the DB:
All scripts slow down if you don't cache, or pre-load, SQL query results for those lookups;
complexity, as you have to do the right SQL query, and you depend on QC's data model in a quite peculiar way (usually a horror when you're upgrading)
If looking up in an array, or dictionary:
You either must maintain its initialization (bet other admin guys adding a cust field will forget that easily), or must "load" it from QC's table (which is a bit like the SQL solution above, and has the same downsides).
I'd go with the array/dictionary-initialized-from-db-idea. Or, if you can live with the constant idea already presented, that one is a good bet. Considering that there is no session-independent scope in QCs customizing scripts, the SQL access idea might really kill performance because it would have to be executed for every new user session. Which is why I, too, +1'd the constant idea.
Look at this:
Dim gFieldLabelToNameDICT: Set gFieldLabelToNameDICT = CreateObject("Scripting.Dictionary")
gFieldLabelToNameDICT.CompareMode = vbTextCompare
Function GetNameOfLabel (strFieldLabel)
' If it doesn't exist yet in fieldLabelToName dict -> search it using TDC and add it to the list to improve performance
If Not gFieldLabelToNameDICT.Exists(strFieldLabel) Then
Dim testSetFields As List
Dim testSetFields: Set testSetFields = QCUtil.QCConnection.Customization.Fields.Fields("RUN")
For Each aField in testSetFields
If aField.UserLabel = strFieldLabel Then
gFieldLabelToNameDICT.Item(strFieldLabel) = aField.ColumnName
End If
Next aField
End If
GetNameOfLabel = gFieldLabelToNameDICT.Item(strFieldLabel)
End Function
Maybe you shall want to add some more error handling, such us considering the case that the label is not found.