Since we can query on the XML file from C# (.NET), why do we need an XSD file? I know it is metadata file of particular XML file. We can specify the relationships in XSD, but what is its functioning then?
XML
<?xml version="1.0" encoding="utf-8" ?>
<Root>
<Customers>
<Customer CustomerID="GREAL">
<CompanyName>Great Lakes Food Market</CompanyName>
<ContactName>Howard Snyder</ContactName>
<ContactTitle>Marketing Manager</ContactTitle>
<Phone>(503) 555-7555</Phone>
<FullAddress>
<Address>2732 Baker Blvd.</Address>
<City>Eugene</City>
<Region>OR</Region>
<PostalCode>97403</PostalCode>
<Country>USA</Country>
</FullAddress>
</Customer>
</Customers>
<Orders>
<Order>
<CustomerID>GREAL</CustomerID>
<EmployeeID>6</EmployeeID>
<OrderDate>1997-05-06T00:00:00</OrderDate>
<RequiredDate>1997-05-20T00:00:00</RequiredDate>
<ShipInfo ShippedDate="1997-05-09T00:00:00">
<ShipVia>2</ShipVia>
<Freight>3.35</Freight>
<ShipName>Great Lakes Food Market</ShipName>
<ShipAddress>2732 Baker Blvd.</ShipAddress>
<ShipCity>Eugene</ShipCity>
<ShipRegion>OR</ShipRegion>
<ShipPostalCode>97403</ShipPostalCode>
<ShipCountry>USA</ShipCountry>
</ShipInfo>
</Order>
<Order>
<CustomerID>GREAL</CustomerID>
<EmployeeID>8</EmployeeID>
<OrderDate>1997-07-04T00:00:00</OrderDate>
<RequiredDate>1997-08-01T00:00:00</RequiredDate>
<ShipInfo ShippedDate="1997-07-14T00:00:00">
<ShipVia>2</ShipVia>
<Freight>4.42</Freight>
<ShipName>Great Lakes Food Market</ShipName>
<ShipAddress>2732 Baker Blvd.</ShipAddress>
<ShipCity>Eugene</ShipCity>
<ShipRegion>OR</ShipRegion>
<ShipPostalCode>97403</ShipPostalCode>
<ShipCountry>USA</ShipCountry>
</ShipInfo>
</Order>
</Orders>
</Root>
I want to get data from the Order elements according to a provided CustomerID.
Also: What is the purpose of giving the relationships in XSD?
XSD files are used to validate that XML files conform to a certain format.
In that respect they are similar to DTDs that existed before them.
The main difference between XSD and DTD is that XSD is written in XML and is considered easier to read and understand.
Without XML Schema (XSD file) an XML file is a relatively free set of elements and attributes. The XSD file defines which elements and attributes are permitted and in which order.
In general XML is a metalanguage. XSD files define specific languages within that metalanguage. For example, if your XSD file contains the definition of XHTML 1.0, then your XML file is required to fit XHTML 1.0 rather than some other format.
You mention C# in your question so it may help to think of as XSD as serving a similar role to a C# interface.
It defines what the XML should 'look like' in a similar way that an interface defines what a class should implement.
XSDs constrain the vocabulary and structure of XML documents.
Without an XSD, an XML document need only follow the rules for being well-formed as given in the W3C XML Recommendation.
With an XSD, an XML document must adhere to additional constraints placed upon the names and values of its elements and attributes in order to be considered valid against the XSD per the W3C XML Schema Recommendation.
XML is all about agreement, and XSDs provide the means for structuring and communicating the agreement beyond the basic definition of XML itself.
Also questions is: What is the purpose
of giving the relationships in xsd.
Suppose you want to generate some XML for an external party's tool, or similar - how would you know what structure it is allowed to follow to be used correctly for their tool? you write to a schema. Likewise if you want other people to use your tool, you would write a schema for them to follow. It may also be useful for validating your own XML.
Before understanding the XSD(XML Schema Definition) let me explain;
What is schema?
for example; emailID: peter#gmail
You can identify the above emailID is not valid because there is no #, .com or .net or .org.
We know the email schema it looks like peter#gmail.com.
Conclusion: Schema does not validate the data, It does the validation of structure.
XSD is actually one of the implementation of XML Schema. others we have relaxng
We use XSD to validate XML data.
An XSD is a formal contract that specifies how an XML document can be formed. It is often used to validate an XML document, or to generate code from.
An XSD file is an XML Schema Definition and it is used to provide a standard method of checking that a given XML document conforms to what you expect.
An .xsd file is called an XML schema. Via an XML schema, we may require a certain structure in a given XML - which elements in which order, how many times, with which attributes, how they are nested, etc. If we have a schema for our XML input, we can verify that it contains the data we need it to contain, and nothing else, with a few lines invoking a schema validator.
The xsd file is the schema of the xml file - it defines which elements may occur and their restrictions (like amount, order, boundaries, relationships,...)
I have EDM model classes generated by entity FrameWork DB first approach. Everytime I update EDMX all the classes that have I added validation,schema, attribute names to be displayed are gone.
What is the best approach to handle this situation ?
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The generated classes are partial, so you can generate your own properties and methods into a new partial class (in different file) for associate generated class.
Hope my answer could help.
Based on this example Keep child-parent relationship after unmarshalling I'd like to know if it's possible to unmarshall xml file into an existing model (not having the JAXB annotations). My idea is to directly unmarshall into Primefaces Menu Model (https://www.primefaces.org/docs/api/6.0/org/primefaces/model/menu/package-summary.html). Is it possible?
JAXB is configuration by exception, so if your model matches the xml, annotations are not necessary.
Here a blog post and a stackoverflow answer by Blaise Doughan on the topic.
It is possible (if your model is straightforward enough to be JAXB-compatible or with MOXy external mappings), but I would really not recommend it.
If you map to existing model, your XML representation becomes dependent on this existing model. And should the existing model change (like, you update the version of the library you use), you won't be able to unmarshal existing XML and will need migration mechanisms.
From my point of view, it is better to write an XML Schema and compile it to schema-derived classes. Then have a conversion routine to transfrom unmarshalled object structure to the target existing model.
usually, JAXB is used to generate code from an xsd, which generates java classes for xsd complexType with annotations to convert it to xml and vice-versa.
I am trying to achieve something different. I want, to generate a data mapper class for each such xsd element. The mapper will map each field of the generated class with values from another datatype (say from database, or other stream)
so i need to: for every user-defined datatype in xsd, add a method in a DataMapper class map-<XSD-ComplexDataType-Class>() and generate method body.
to achieve this, i think it is not possible to generate this class in a Plugin extending com.sun.tools.internal.xjc.Plugin as in the run method, i wont be able to create a new JDefinedClass
is there any way to add a hook method before Model invokes Plugins ?
thanks,
There are a few things you can do. In my other answer I specificaly meant these:
In a plugin you can write and set your own com.sun.tools.xjc.generator.bean.field.FieldRendererFactory. Field renderers generate a FieldOutlines from CPropertyInfos. This is a step between the model and the outline. So if you want different code generated out of the model, consider implementing your own FieldRendererFactory. You can register a FieldRendererFactory via XJC plugin (see Options.setFieldRendererFactory(...)).
On the class level, you can write your own com.sun.tools.xjc.generator.bean.BeanGenerator and use it for code generation.
You can just use model and generate the code completely on your own. I do this in Jsonix when I produce JavaScript mappings for XML<->JSON.
As for your specific task, I would actually just postprocess the code model in the run method of your plugin. You have everything there - the model, the outline and also the code model (see outline.getCodeModel()). And you can definitely create your JDefinedClasses there, the code model exists already.
How to get the description field on a type populated in the generated enunciate documentation?
We are generating classes from jaxb using jaxb2-maven-plugin. No matter how I document a element either using the <xsd:documentation></xsd:documentation> or the
<xsd:appinfo>
<jaxb:class>
<jaxb:javadoc>
</jaxb:javadoc>
</jaxb:class>
</xsd:appinfo>
it is overwritten in the generated classes. Can I somehow disable the this auto-generated javadoc from this plugin? Or what does enunciate really expect me to do let me document on a field level?
Note that the comment I write on class-level/type does show up in the generated class and in the enunciated generated documentation.
We are using enunciate (v.1.26.2) and jaxb2-maven-plugin (v. 1.5)
So you're wondering how to get Enunciate to not use the Javadocs on the class?
One way might be to compile the JAXB-generated classes and run Enunciate against the compiled classes instead of the source code.