I'm trying to get a value from an interface (it should be a pointer to another struct, see).
Actually, I have to know the type of the pointer to access to the data it and it bother me. That's why I would like to use reflect package to do it better.
Actually, I can display the type using reflect.TypeOf(event.Event).String() but I don't understand how to change this line in the example without specifying with something like .(*marathon.EventDeploymentStepSuccess)
Related
In the json package if you want to utilize tags to marshall and unmarshall structs the field must be exported. I always thought this was a limitation on the reflect package but it seems to be explicitly rejected here.
I would like to know what I am missing or the design choices behind this as it creates one of the following issues normally.
Exporting more fields than I want allowing users to change values without using potential getters and setters.
A lot of extra code if you chose to solve the above problem by making a second identical struct just for tag usage and make it unexported.
Here is a playground of code being able to read unexported tags.
Edit: Better playground thanks to #mkopriva
I'm writing a function that iterates over the methods on a given struct and binds the methods to handlers. I would like to skip over internal methods if possible. I'm not sure if this is possible to do so explicitly - I reviewed the documentation for the reflect package and I didn't see a means to detect if a given Value is an internal method. I know I can get the method's name, and then check if it starts with a lowercase character but I'm not sure if there's a kosher way to accomplish this. It's also possible that the internal / public boundary really only exists at compile time anyways, so there really isn't even a way of knowing this beyond the method's name. In either case I'd like to know for sure. Thanks!
The reflect package will not give you unexported methods via Type.Method. Pretty much, if you can see it via reflect, it is already exported.
See https://play.golang.org/p/61qQYO38P0
I want to get a variable's class type in freemarker, used var.class.simpleName;
but if var is a Map, freemarker will process class as a key to find value in var.
it throw exception. how can I do this ? thanks for any suggestion.
First I have to ask why do you need that, because FreeMarker templates aren't supposed to know even if var is Map at all. Maybe your data-model is not what the template needs.
Anyway, for now, I would write a custom TemplateMethodModelEx for this purpose, something that you can use like ${classOf(var)}. Inside the TemplateMethodModelEx implementation you will receive a TemplateModel as the argument value, and then you can check if it's an AdapterTemplateModel, and if so you can get back the original object and get its class. (If it's not a AdapterTemplateModel, then it perhaps isn't even a wrapped Java object, so it doesn't make sense to ask what the class of the original object is.) However, the DefaultObjectWrapper with incompatibleImprovements set to less than 2.3.22 doesn't give AdapterTemplateModel to wrapped Map-s... so in 2.3.21 you will still have to use BeansWrapper, but you can at least set simpleMapWrapper to true.
In 2.3.22 it will be actually possible to write ${var?api.class}... you might use the nightly build. Though it only supposed to solve the problem where you can't access business methods because the primary type of the business class is Map.
Is it possible to get a slice of strings that represent the names of all types that implement an interface or inherit from a specific struct in a specific package using reflection?
After some research on the reflect package's doc, I don't think it's possible. That's not the way reflection work in go: the interfaces mechanism not beeing declarative (but duck-typed instead), there is no such list of types.
That said, you may have more luck using the ast package to parse your project, get the list of types, and check wheter or not they implement an interface, then write some code to give you the said slice. That would add a step to compilation, but could work like a charm.
AFAIK, you can't do this with reflect, since packages are kinda out of reflect's scope.
You can do this the same way godoc's static analysis works. That is, using code.google.com/p/go.tools/go/types to parse the package's source code and get the type info.
The go oracle can do this. https://godoc.org/code.google.com/p/go.tools/oracle
Here is the relevant section of the user manual.
I have been trying to use BLToolkit to activate an Oracle stored procedure which takes a User Defined Type as an argument as an output parameter and changes it.
I have managed to do this on a primitive type, and and also by manually calling SetSpCommamd however I would like to use the abstract class generation method but can't seem to get it to work.
I'm pretty sure the code I wrote is correct (works for the primitive). When debugging I found the SetSpCommamd called by the generated code gets wierd parameters instead of the ones I provided as opposed to when I call the method manually (the it gets the exact parameters I'd like). I wish I could see the code generated by the reflection emit to see what's wrong there.
Can anyone please help me figure out why this is not working?
Found the problem (Potentially a bug in BLToolkit).
BLToolkit does not pass the UDT Class as is to the procedure (instead it tries to flatten it or something and pass the insides of the object). I Changed the object to a Struct instead of a Class and that fixed it.
Later on I also changed it back to class and made a patch in the 'IsScaler()' method in BLToolkits code.
I will report this as a Bug I hope they fix it.