In my AutoMapper scenario, I have a string property on my source type but a Uri property on the destination. Occasionally, this conversion is expected to fail when the source data is bad:
UriFormatException: Invalid URI: The hostname could not be parsed.
at Uri.ctor(String uriString)
When this happens, I would like AutoMapper to set the problematic property to null on the destination & continue on with the process of mapping the other elements. Known solutions to this are:
Writing a custom converter (with try/catch) just for that element
Using BeforeMap() as described here
But I feel that if I have to take those extra steps, AutoMapper hasn't fulfilled its promise as a time-saving tool. Isn't there some global 'continue-on-error' flag that I can set? Note that I am less concerned about Uris in particular than I am about the lack of configurable error handling.
No special setup needed to repro this--just a vanilla CreateMap() call that registers two classes with differently typed properties.
Related
We have a central logging component which I am now trying to use in a WebJob that I am developing. I am basically following this example. My Activator is identical, I have the bindingModule that has my Bind statements in it. One thing I have done differently here is to use the method versions:
Kernel.Bind(typeof(IExternalSystemLogger)).To(typeof(ExternalSystemLogger));
instead of the generic versions in the example. I currently have constructor injection implemented but I have also set up the parameter injection as per the example. Which ever way I try to do this I end up with the error:
Error indexing method 'Functions.ProcessQueueMessage' ---> System.InvalidOperationException: Cannot bind parameter
or
a null reference exception (with parameter injection). Further into the error I am told that
Make sure the parameter Type is supported by the binding
which is the part that I am finding it difficult to resolve. I have looked at the available method calls on the config object available in WebJob.program but none seems to work. What is it I need to call so that I am correctly resolving my type when I am using a QueueTrigger or BlobTrigger?
I am simply using a cftry/cfcatch block for handling any exception. Take this simple exception:
<cftry>
<cfset abc = 1/0>
<cfcatch>
<cfdump var="#cfcatch.getClass().getName()#">
<cfdump var="#isStruct(cfcatch)#">
<cfdump var="#isObject(cfcatch)#">
<cfdump var="#structKeyExists(cfcatch, 'type')#">
</cfcatch>
</cftry>
And the above code's output is like this:
coldfusion.runtime.DivideByZeroException
NO
YES
YES
My question is:
Why structKeyExists is not throwing an error as cfcatch is not of type struct?
And on dumping cfcatch it seems like it is a struct.
Any suggestions.
I think what is confusing you is that you need to remember that ColdFusion is a typeless language.
ColdFusion documentation on data types
Data types
ColdFusion is often referred to as typeless because you do not assign types to variables and ColdFusion does not associate a type with the variable name. However, the data that a variable represents does have a type, and the data type affects how ColdFusion evaluates an expression or function argument. ColdFusion can automatically convert many data types into others when it evaluates expressions. For simple data, such as numbers and strings, the data type is unimportant until the variable is used in an expression or as a function argument.
ColdFusion variable data belongs to one of the following type categories:
Simple One value. Can use directly in ColdFusion expressions. Include numbers, strings, Boolean values, and date-time values.
Binary Raw data, such as the contents of a GIF file or an executable program file.
Complex ** A container for data. Generally represent more than one value. ColdFusion built-in complex data types include arrays, structures, queries, and XML document objects. You cannot use a complex variable, such as an array, directly in a ColdFusion expression, but you can use simple data type elements of a complex variable in an expression. For example, with a one-dimensional array of numbers called myArray, you cannot use the expression myArray * 5. However, you could use an expression myArray3 * 5 to multiply the third element in the array by five.
Objects Complex constructs. Often encapsulate both data and functional operations. The following table lists the types of objects that ColdFusion can use, and identifies the chapters that describe how to use them:
So the code within the <cfcatch> block contains an object that can be referred to as a "structure". By default the name of that structure is cfcatch. You can override that name by specifying the name attribute within the <cfcatch> tag.
The easiest way to see everything that is available to you is to <cfdump> the entire structure within the <cfcatch> block.
<cfcatch>
<cfdump var="#cfcatch#">
</cfcatch>
CFCatch documentation on cfcatch
The cfcatch variables provide the following exception information:
cfcatch variable Content
cfcatch.type Type: Exception type, as specified in cfcatch.
cfcatch.message Message: Exceptions diagnostic message, if provided; otherwise, an empty string; in the cfcatch.message variable.
cfcatch.detail Detailed message from the CFML interpreter or specified in a cfthrow tag. When the exception is generated by ColdFusion (and not cfthrow), the message can contain HTML formatting and can help determine which tag threw the exception.
cfcatch.tagcontext An array of tag context structures, each representing one level of the active tag context at the time of the exception.
cfcatch.NativeErrorCode Applies to type = "database". Native error code associated with exception. Database drivers typically provide error codes to diagnose failing database operations. Default value is -1.
cfcatch.SQLState Applies to type = "database". SQLState associated with exception. Database drivers typically provide error codes to help diagnose failing database operations. Default value is 1.
cfcatch.Sql Applies to type = "database". The SQL statement sent to the data source.
cfcatch.queryError Applies to type ="database". The error message as reported by the database driver.
cfcatch.where Applies to type= "database". If the query uses the cfqueryparam tag, query parameter name-value pairs.
cfcatch.ErrNumber Applies to type = "expression". Internal expression error > number.
cfcatch.MissingFileName Applies to type = "missingInclude". Name of file that could not be included.
cfcatch.LockName Applies to type = "lock". Name of affected lock (if the lock is unnamed, the value is "anonymous").
cfcatch.LockOperation Applies to type = "lock". Operation that failed (Timeout, Create Mutex, or Unknown).
cfcatch.ErrorCode Applies to type = "custom". String error code.
cfcatch.ExtendedInfo Applies to type = "application" and "custom". Custom error message; information that the default exception handler does not display.
(Too long for comments..)
Adding to Miguel-F's comments about CF's "typelessness"... according to the documentation, IsStruct uses the following rules (emphasis mine):
Returns True, if variable is a ColdFusion structure or is a Java
object that implements the java.lang.Map interface. The return value
is False if the object in variable is a user-defined function (UDF).
CFCatch does not meet that criteria. Hence why IsStruct returns false.
If you dump the cfcatch object, and examine the class hierarchy, you will see it is actually implemented as a subclass of java.lang.Exception:
coldfusion.runtime.DivideByZeroException
coldfusion.runtime.ExpressionException
coldfusion.runtime.NeoException
java.lang.RuntimeException
java.lang.Exception
java.lang.Throwable
java.lang.Object
... not coldfusion.runtime.struct ie CF structure:
coldfusion.runtime.Struct
coldfusion.util.FastHashtable
coldfusion.util.CaseInsensitiveMap
java.lang.Object
So as Miguel-F said, though it can be used like a structure (as can most complex object), technically it is not a CF structure, which explains why IsStruct returns false.
As an aside, the reason you can access its properties using dot notation, like with CF structures, is probably because the cfcatch class uses the JavaBean pattern:
ColdFusion can automatically invoke get_PropertyName_() and
set_PropertyName_(value) methods if a Java class conforms to the
JavaBeans pattern. As a result, you can set or get the property by
referencing it directly, without having to explicitly invoke a method.
So for example, you can access the "message" property of cfcatch using:
cfcatch.message
.. instead of invoking its "getter" method for that property:
cfcatch.getMessage()
cfcatch object acts like a struct, but it is not one. This is a special case.
What you can do is make a duplicate of cfcatch object and try isStruct method on it, it will return true.
for example-
<cftry>
<cfset abc = 1/0>
<cfcatch>
<cfset dup = duplicate(cfcatch)>
<cfdump var="#isStruct(dup)#">
<cfdump var="#isStruct(cfcatch)#">
<cfdump var="#isObject(cfcatch)#">
</cfcatch>
</cftry>
The output would be like
YES
NO
YES
I am trying to load some object through bytecode modification using asm bytecode instrumentation library.
I am retransforming the classes using retransformClasses() method.
I am loading the objects in this way :
super.visitVarInsn(Opcodes.ALOAD, 0);
super.visitFieldInsn(Opcodes.GETFIELD, owner, name, desc);
super.visitMethodInsn(org.objectweb.asm.Opcodes.INVOKESTATIC,
"com/coolcoder/MyClass",
"objectCheckTest",
"(Ljava/lang/Object;)V");`
The problem is that I the objects are getting loaded using usual tranform() of ClassTransformer , but when I am using Attach API's retranformClasses() , these objects are not getting loaded . Strange thing is that , I am not getting any bytecode error either.
Am I doing something wrong ? or am I missing some intricate part regarding retransform ?
I was be able to solve the issue , though I do not know why it happened in the first place.
(1) I was loading the object only on PUTFIELD or PUTSTATIC opcodes, i.e , when the object value is being set.
(2) Just after bytecode modification the class is getting redefined , as a result of which the code snippet did not work.
(3) Next time when the class loaded due to redefinition , the object is already being set , so it will not be called again.
(4) Now , when I checked for GETFIELD or GETSTATIC opcodes , i.e when the object's value is being retrieved and I loaded it , I was able to view its details.
The same approach which I mentioned above is working fine in usual transformation (i.e running with premain).
Any idea on this erratic behaviour of redefinition ?
First, in manifest.mf file,Can-Retransform-Classes attribute should be true.
And your ClassFileTransformer instance should be add with the true value for parameter canRetransform in method addTransformer .
Here is another additional tips:
If the transformer throws an exception (which it doesn't catch), subsequent transformers will still be called and the load, redefine or retransform will still be attempted. Thus, throwing an exception has the same effect as returning null. To prevent unexpected behavior when unchecked exceptions are generated in transformer code, a transformer can catch Throwable. If the transformer believes the classFileBuffer does not represent a validly formatted class file, it should throw an IllegalClassFormatException; while this has the same effect as returning null. it facilitates the logging or debugging of format corruptions.
from java api docs
So, there maybe some uncatched exception which will be just ignored by the jvm arised.
You can put a try..catch
Please forgive my poor English ...
Hypothetic and academic question.
pseudo-code:
<pre><code>
class Book{
read(theReader)
}
class BookWithMemory extends Book {
read(theReader, aTimestamp = null)
}
</pre></code>
Assuming:
an interface (if supported) would prohibit it
default value for parameters are supported
Notes:
PHP triggers an strict standards error for this.
I'm not surprised that PHP strict mode complains about such an override. It's very easy for a similar situation to arise unintentionally in which part of a class hierarchy was edited to use a new signature and a one or a few classes have fallen out of sync.
To avoid the ambiguity, name the new method something different (for this example, maybe readAt?), and override read to call readAt in the new class. This makes the intent plain to the interpreter as well as anyone reading the code.
The actual behavior in such a case is language-dependent -- more specifically, it depends on how much of the signature makes up the method selector, and how parameters are passed.
If the name alone is the selector (as in PHP or Perl), then it's down to how the language handles mismatched method parameter lists. If default arguments are processed at the call site based on the static type of the receiver instead of at the callee's entry point, when called through a base class reference you'd end up with an undefined argument value instead of your specified default, similarly to what would happen if there was no default specified.
If the number of parameters (with or without their types) are part of the method selector (as in Erlang or E), as is common in dynamic languages that run on JVM or CLR, you have two different methods. Create a new overload taking additional arguments, and override the base method with one that calls the new overload with default argument values.
If I am reading the question correctly, this question seems very language specific (as in it is not applicable to all dynamic languages), as I know you can do this in ruby.
class Book
def read(book)
puts book
end
end
class BookWithMemory < Book
def read(book,aTimeStamp = nil)
super book
puts aTimeStamp
end
end
I am not sure about dynamic languages besides ruby. This seems like a pretty subjective question as well, as at least two languages were designed on either side of the issue (method overloading vs not: ruby vs php).
I am working with the classes in the System.Windows.Documents namespace, trying to write some generic code that will conditionally set the value of certain dependency properties, depending on whether these properties exist on a given class.
For example, the following method assigns an arbitrary value to the Padding property of the passed FrameworkContentElement:
void SetElementPadding(FrameworkContentElement element)
{
element.SetValue(Block.PaddingProperty, new Thickness(155d));
}
However, not all concrete implementations of FrameworkContentElement have a Padding property (Paragraph does but Span does not) so I would expect the property assignment to succeed for types that implement this property and to be silently ignored for types that do not.
But it seems that the above property assignment succeeds for instances of all derivatives of FrameworkContentElement, regardless of whether they implement the Padding property. I make this assumption because I have always been able to read back the assigned value.
I assume there is some flaw in the way I am assigning property values. What should I do to ensure that a given dependency property assignment is ignored by classes that do not implement that property?
Many thanks for your advice.
Tim
All classes that derive from Block have the Padding property. You may use the following modification:
void SetElementPadding(FrameworkContentElement element)
{
var block = element as Block;
if (block == null) return;
block.Padding = new Thickness(155d);
}
Even without this modification everything would still work for you because all you want is for Padding to be ignored by classes that do not support it. This is exactly what would happen. The fact that you can read out the value of a Padding dependency property on an instance that does not support it is probably by design but you shouldn't care. Block and derivatives would honor the value and all others would ignore it.