I know that #XmlJavaTypeAdapter allows me to change a list of xml object to map.
may I know if is possible to compute a value during xml unmarshalling?
for example a date of birth is coming in.
and i have a age field. I wish to compute the age field when xml is unmarshalling.
An XmlAdapter is used any time the representation in your object differs from the XML representation. XmlAdapter gives you a place to insert custom logic. It sounds like the perfect fit for your use case.
Related
I am parsing a fixed length field flat file to a java bean using beanio library.
I have certain validations provided to number of fields.
For one of the field, I need to add a mandatory validation if another field is having a certain value.
Is there a way to attain this requirement through beanio?
We are using Spring rest template and jackson json provider to serialize/deserialize json. From my services i send a linkedHashSet back which gets converted to a HashSet on the client side when i receive it. Because of this I loose my insertion order of elements.
Is this the default implementation of jackson json provider for Set ? Is there any other way, so it can deserialize to proper implementation? I feel it's gonna be tricky but inputs will be highly appreciated from you guys.
Thanks
You can specify the concrete class for Jackson to use with the #JsonDeserialize annotation. Just put:
#JsonDeserialize(as=LinkedHashSet.class)
On the property's setter.
It all depends on what you ask the result type to be: if ask data to be mapped to a LinkedHashSet, then JSON Array gets mapped to it. If you use a vague type like java.lang.Object (or java.util.Collection), you will get ArrayList for JSON Arrays.
Keep in mind that JSON is data, not objects (by default), so metadata regarding Java types you used is not passed by default. There are ways to do that, if you need it, but usually you will simply need to provide expected type.
I have some domain classes and i want to init and fill those classes with sample hardcode data , is there any method which i can fill data with any framework ?
For Example : List<Customer> should be filled with some mock data
Consider maintaining your test data in a JSON structure, and use a framework (e.g. google-gson) to deserialize the data into value objects.
If you wish to auto-generate random data, you might want to look into something like Quickcheck, which seems to be Java's equivalent of the .NET framework Autofixture.
As #ipavlic wrote, you might make your constructor generate some random data when the object is created.
You may store the data in a DB or a simple text file and read it from there when you fill your list.
You may combine aproach 1 and 2 and store possible field values in a file or somewhere else and fill the Object fields with these randomly chosen predefined values.
If you want fill list of Customer, there is this method Collections.fill(java.util.List, T) to fill list. This method replace current objects in list. If list is empty it won't fill.
You can put your hard-coded data in a constructor.
If it's mocking frameworks that you are after (as you indicate in comments), then take a look at e.g. Mockito.
I am developing a java application which needs a special component for dynamic attributes. The arguments are serialized (using JSON) and stored in a database and then deserialized at runtime. All attributes are displayed in a JTable with 3 columns (attribute name, attribute type and attribute value) and stored in a hashmap.
I have currently two problems to solve:
The hashmap can also store objects and the objects can be set to null. And if set to null i dont know which class they belong to. How could i store objects even if they are null and known which class they belong to? Do i need to wrap each object in a class that will holds the class of the stored object?
The objects are deserialized from json at runtime. The problem with this is that there are many different types of objects and i don't actually know all object types that will be stored in the hashmap. So i am looking for a way to dynamicly deserialize objects.. Is there such a way? Would i have to store the class of the object in the serialized json string?
Thanks!
Take a look to the Null Object Pattern. You can use an extra class to represent a Null instance of your type and still could contain information about itself.
There is something called a Class Token, Which is the use of Class objects as keys for heterogeneous containers. Take a look to Effective Java By Joshua Bloch, Item 29. I'm not sure how this approach could work for you since you may have many instances of the same type but I leave it as a reference.
First of all, can you motivate why you use JSON serialization for your attributes ?
This method is disadvantageous in many ways in my opinion, it can cause problems with database search and indexing, make database viewing painful and caus unnecessary code in your application. These problems can be not an issue, it depends how you want to use your attributes.
My solution for situation like these is simple table containing columns like:
id - int
attribute_name - varchar
And then add columns for each supported data type:
string_value - varchar
integer_value - int
date_value - date
... and any other types you want.
This design allow for supreme performance using simple and typesafe ORM mapping without any serialization or other boilerplate. It can store values of any type, you just set correct column for attribute type, leaving all other with null. You can simulate null value by using null in all data columns. Indexing and searching also becomes a piece of cake.
Assuming some xml like
<foo>
<bar>test</bar>
</foo>
Evaluating an expression with returnType = String like
/foo/bar
will return "test". However, I'd like to get the serialized xml instead, so something like
<bar>test</bar>
should be returned instead. As I can not check for the returnType in java's xpath implementation (xerces), I cannot simply get an object as result and if it indeed is a node, convert it to serialized xml.
Note: I don't know whether the expression will actually return a node, a string, a number or whatever so I cannot provide an appropriate return type to the eval function except string which, as my problem states, returns the text content and not the serialized xml.
So I am curious -> is there either a java- or (preferred) a xpath-way (function?) to get serialized xml for type string instead of the text children of the selected node?
thanks!
Alex
use the xpath return type XPathConstants.NODE and then you can serialize the returned Node yourself.
Now, you are right to observe that it's difficult to discover the return type of the result; this is a real design weakness of JAXP.
If it's a problem to you, consider using Saxon's s9api interface, which returns XdmValue objects whose type you can interrogate; you also get XPath 2.0 access as a bonus.
As Michael Kay answered, this is difficult in JAXP (the native Java interface).
In Mr Kay's Saxon library's s9api API (see Evaluating XPath Expressions using s9api), once you've called XPathSelector.evaluate() or XPathSelector.evaluateSingle() you can get the XML serialisation by calling XdmValue.toString().
However, if the XPath selected an attribute (e.g. //#name) you will still get the XML serialisation, e.g. name="value". You can call XdmItem.getStringValue(), but for elements that method will return the same values you're already seeing - the textual content of the element, not the serialisation. I've posted separately about how to distinguish between attributes and elements returned from Saxon s9api.