I want mybatis to call a factory method to create an object instead of a constructor. So that for null valued attributes i can return a NULL object(which has overridden behavior to handle all the edge cases) instead of actual object. Can i achieve that with mapper.xml?
Define your own ObjectFactory
http://www.mybatis.org/core/configuration.html#objectFactory
To answer your specific question, there is no way to specify a factory method directly (and only) in the mapper.xml file itself, as far as I know. However, there are two options in MyBatis to do what you want:
As stated in Bhaskar's answer you can use an ObjectFactory.
In theory, you can also define a TypeHandler, but I was unable to get this to work in my recent testing.
If you would like to see a working example of how to use a MyBatis ObjectFactory to implement a Null object, see koan19 of my MyBatis koans: https://github.com/midpeter444/mybatis-koans. (Look in the completed-koans/koan19 directory for the solution I came up with.)
Related
As the topic, when I use ortools, I want to serialize cpsolver, CpSolverSolutionCallback and cpmodel to achieve multithread computing. However, I can't just serialize those objects directly and I think I need to only serialize their configuration and reset configuration in each thread, such as all the constraint and variables in the cpmodel and parameters in cpsolver. This is the question, how can I get all those values using ortools? Is there an api or something? I can't find it when searching on Google.
Every language implements a thin wrapper above a protocol buffer file.
This file is described here
This model is accessible from each CpModel class.
Now you can distribute work using this proto directly. You will need to look at the CpSolver class to understand how the c++ Solve method is called.
See the python solve method.
The way to implement your request.
Create your model normally.
Extract the underlying protocol buffer model underneath and use it for parallelism/distribution.
Solve will returns a CpSolverResponse object. To get the value of a variable in the response, call response.Value(var.Index()), or store the index of the relevant variables and use it in the Value() method call.
In glade it is possible to set an unique ID to an object. In the code one can obtain a pointer to this object by searching for it's "glade ID" via gtk_builder_get_object().
However for my current use-case I just want to read out this ID from an GObject. What's the API to do so ?
You can't. The builder ID is stored in the builder internally, not in the GObject.
The reason for this is that IDs must be unique per builder, which would be impossible to enforce if you were able to get and set them via some GObject API.
You could use gtk_widget_get_name() to identify an object.
It is possible using Gtk.Buildable.get_name(object). This method will return the Glade object id.
This snippet will print all object ids in your Glade XML:
builder = Gtk.Builder()
builder.add_from_file("my-window.glade"))
for obj in builder.get_objects():
print(Gtk.Buildable.get_name(obj))
As stated by #ptomato it's seems not possible.
I found that in that line in the documentation:
All the fields in the GObject structure are private to the
implementation and should never be accessed directly.
But you can circumvent it because at one point in your code you were refering to it by the id that you typed in (or the code you wrote type in) so you just need to store it at that point. And link it somehow (with a variable or a data structure) to the name of the variable holding the object.
Is there any way to create a fake from a System.Type object in FakeItEasy? Similar to:
var instance = A.Fake(type);
I try to write a fake container for AutoFac that automatically return fakes for all resolved types. I have looked in the code for FakeItEasy and all methods that support this is behind internal classes but I have found the interface IFakeObjectContainer that looks pretty interesting, but the implementations still need registration of objects that is the thing that I want to come around.
As of FakeItEasy 2.1.0 (but do consider upgrading to the latest release for more features and better bugfixes), you can create a fake from a Type like so:
using FakeItEasy.Sdk;
…
object fake = Create.Fake(type);
If you must use an earlier release, you could use some reflection based approach to create a method info for the A.Fake() method. (since it's about auto mocking this shouldn't be a problem really).
This is best done using a registration handler. You should look into how AutofacContrib.Moq implements its MoqRegistrationHandler. You'll see that it is actually using the generic method MockRepository.Create to make fake instances. Creating a similar handler for FakeItEasy should be quite simple.
Looks like the class that is generated for PlaceHistoryMapper is hard-coded to use AbstractPlaceHistoryMapper as the super class.
So, I am trying to work around this by trying to replace this AbstractPlaceHistoryMapper with a custom mapper of mine using deferred binding . I am using the following rule in my *.gwt.xml:
<replace-with class="com.google.gwt.place.impl.AbstractPlaceHistoryMapper">
<when-type-is class="com.test.sampleapp.CustomPlaceHistoryMapper" />
</replace-with>
But for some reason the replace does not seem to be happening. CustomPlaceHistoryMapper is not getting kicked in and the generated class still uses AbstractPlaceHistoryMapper.
Any thoughts/pointers as to what might be resulting this behavior are much appreciated.
Note: I have also posted this on the GWT group but haven't received an answer so far.
To make the deferred binding work a class must be created with GWT.create(). However, AbstractPlaceHistoryMapper is only used as an extended class. So it will never be created via GWT.create, but always by instantiation the subclass. And therefor deferred binding won't work in this case. If you want a complete different implementation you have to implement a custom PlaceHistoryMapper, and manage the known tokens yourself. This also means you can't use the History annotations either.
As a side note the classnames in your rule should be swapped. But for the end result this doesn't matter, since it won't work in the first place.
It is absolutely possible to have custom history tokens (eg. #mail or #mail/bla instead of only #mail:inbox) using the out-of-the-box Place-related classes that GWT (2.0) provides.
Instead of replacing AbstractPlaceHistoryMapper you could instantiate the default PlaceHistoryMapper passing in it's constructor your implementation of PlaceHistoryMapper<T> or PlaceHistoryMapperWithFactory<T>.
eg.:
final PlaceHistoryHandler placeHistoryHandler = new PlaceHistoryHandler(new CustomHistoryMapper());
You will be able then to map tokens as you wish.
I personally recommend you to use an unique PlaceTokenizer in you mapper custom implementation so that I dont have to have an inner PlaceTokenizer class in each of your Places.
Hope that helps. Feel free to ask any doubts.
I use contructor injection in my solution, but this one class has a property that i do not want to pass in the constructor where i have the invariant dependencies.
Let's say i got an ILogger and it has a FileName property i want to set, while still having it set the dependancies in the contructor.
How do i go about registering the type, and at the same time pass the defaunt connection string.
I hope there is an easy way to do it - preferably without decorating the property with an attribute, but if the setup is easier with the attribute i guess that's cool :)
So the question is, how do i inject a property value on an object that also uses contructor injection - with Unity.
UPDATE: I mentioned it in the title, but i forgot to elaborate in the body of the text - i want to set these dependencies up manually (in code) as opposed to in a config file.
Ok i guess it helped to ask the question, i found out - here it is.
container.Configure<InjectedMembers>().ConfigureInjectionFor<BasicLogger>(
new InjectionProperty("FileName", #"C:\test.log")
);
If you are injecting properties you have to use [Dependency] or else manually inject that dependency.
You usually want an IConfiguration interface to be injected. This would probably have a LogFile property that you can read.
The Configuration implimentation is usually just a simple wrapper to read items from the config file.