I have got a very strange problem.
In the earlier version of programm i have found the following statement inside a query.
table1!field1 > table2!Field2
I ma not able to understand the meaning of the ! sign here.
Can any one able to help me in this regard
thank you in advance
! means default property with String parameter type in VB/VBA. Apparently Table object has default property Field("fieldname") and Field object has default property Value, thereby instead of table1.Field("field1").Value you can use shortcut notation table1!field1.
Related
I'm using Authorize.net API and they require card expiration field to be formated as "yyyy-mm". We did that with this simple line of code:
expirationDate = model.Year.ToString("D4") & "-" & model.Month.ToString("D2")
and this absolutelly worked. I still have cards stored in the system that were saved using this method! But today I was testing something completelly unrelated, and wanted to add another card, and bam, this code exploded with this exception:
System.InvalidCastException: 'Conversion from string "D4" to type 'Integer' is not valid.'
Inner exception to that one is:
Input string was not in a correct format.
This just... doesn't make sense to me. Why in the world is it trying to convert format specifier (D4) into an integer? What input string? What in the world changed in two days?
The problem is that your are using a Nullable(Of Integer). This is a different structure that does not support the overloads of the ToString method a normal Integer has.
You can view the overloads of the Nullable structure here.
I suggest you use the GetValueOrDefault() method to get the proper Integer and also apply the value you expect in case the value is Nothing.
If it is impossible that a instance with a Nothing set for the year reaches this method you can simply use the Value property.
I still do not fully understand why you get this strange error message. Maybe you could check out what the actual method that is called is? Pointing at the method should give you that information. It can't be Nullable(Of Integer).ToString
Well, I found a workable solution and something of an answer thanks to #Nitram's comment. The type of Year/Month property has been changed from Integer to Integer?. Obviously, this isn't a very satisfying answer because I still don't understand why the nullable int can't be formatted, and yet the code compiles perfectly. The working solution for me has been using static format method on String as so:
expirationDate = String.Format("{0:D4}-{1:D2}", model.Year, model.Month)
This works fine even with nullable types.
Is it possible, in ABAP, to evaluate string templates dynamically?
Normally, you will have some string template in code that will be checked by the compiler. (The variables in the curly brackets are checked by the compiler at compile time).
However, is it possible to have a string evaluated at runtime?
So, instead of:
data(val) = |System ID: { sy-sysid }|.
I would like the string to be interpolated to come from elsewhere, for example:
parameter: p_file type string lower case default '/mnt/{ sy-sysid }/file.txt'.
In this case, I would like to have the value of p_file to be evaluated at runtime to substitute the variable (sy-sysid) with the runtime value.
You could, of course, program your own substitution by finding all occurrences of variables with curly brackets with a regex expression, then evaluate the variable values with ASSIGN and substitute them back into the string, but I am looking for a built-in way to do this.
Sorry, this is maybe a stupid example, but hopefully you understand what I mean. (If not, please let me know in the comments and I will try and clarify).
The problem in your snippet is not with string template but with PARAMETER behavior. It does not allow dynamics in DEFAULT clause.
To achieve what you want you should use INITIALIZATION and set path value in runtime:
parameter: p_file type string lower case.
INITIALIZATION.
p_file = | /mnt/{ sy-sysid }/file.txt |.
Unfortunately, the example you gave, does not make any sense to me. ABAP String templates are evaluated at run-time and type-checked at compile-time.
In your example, it is always the run-time value of SY-SYSID that will be written to the variable.
I guess what you want to do is circumvent compile-time checks for expressions inside a string template.
Please try to give us your actual use case, so maybe we find an even better solution to your problem.
However, here is what I think could help you:
Personally, I do not recommend to write code like the one below, because it is extremely error-prone likely to mislead other programmers and because there is very likely a better solution.
Given that you know the name of a variable at run-time, try this:
".. say LV_VARNAME is a charlike variable that contains a
" variable name at runtime.
"NOTE that the variable LV_VARNAME must be visible in the scope of the
"following code.
FIELD-SYMBOLS: <my_var> TYPE any.
ASSIGN (lv_varname) TO <my_var>.
DATA(lv_str) = |The value is { <my_var> }|.
Compare weirdness when working with LINQ and Entity Framework.
I want to retrieve an ID from my DB and I get this weird message.
I could simply fix it as you can see but I want to understand why this happens.
Question:
Why do I get this error message even if I check with "HasValue" or I use "FirstOrDefault"? It can't be null in my opinion but I obviously miss something.
Add .Value if you are 100% sure the Integer? has a value.
Why do I get this error message even if I check with "HasValue"
Entity Framework just uses the objects you give it. It can't create a new object where OPX_ isn't nullable.
the setOpxRights function presumably takes an Integer as a parameter and Option Strict On won't allow an Integer? to be implicitly converted to an Integer. If you are sure that it will always have a value, pass in cctUser.OPX_Rechte.Value
The compiler is not perfect, we can see that OPX_Rechte will have a value because of the where statment, but for the compiler you are just using a the object cctUser that have an Integer? and it needs an Integer.
I have read some documents about the syntax ->*, but i still don't get it. Can anyone explain what it means and in what scenarios I can use it?
I have that syntax in this example:
assign ovs_callback_object->query_parameters->* to <ls_query_params> CASTING.
refvar->* is used to de-reference an unstructured reference variable. For a structured reference, you would use structref->component to access a component of the referenced object (an attribute of an object or a component of a structure). If you have something like TYPE REF TO i, there's no inner structure, so you have to use the special syntax ->*. It's all in the documentation...
The ->* operator is the "Dereference" operator. It turns a TYPE REF TO something into a TYPE something.
In your example, ovs_callback_object->query_parameters is likely a reference, but you don't want to assign the reference to the field-symbol, you want to assign the actual field the reference points to.
As you seen in this picture below, for some reason my DirectCast wont except ANYTHING for the second argument. It says it requires a type, but, it won't take any object at all!
Thanks for any help! I'm using VB.net so all .net answers are acceptable :)
EDIT
Ok, so apparently I'm not giving it the right kind of type. Could somebody please clarify this? Assuming the type it needs to cast to is gridElement, what should I replace objType with?
DirectCast requires an object prototype (i.e. just giving it the intended class name) rather than a System.Type descriptor object. To cast an object using a System.Type, you will want to utilize CTypeDynamic():
Return CTypeDynamic(createElementByIdAndLayer.MemberwiseClone(), objType)
The error is essentially telling you a class with the type name "objType" does not exist.
Its expecting a "Type", not a "Type Object".
What is the return value of the function?