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 the following data model.
A Page type with a repeating group names files. Inside the repeating group, there is a node-selector to select files name file
Then I need to index the metadata of the page with the metadata of the file in order to do a search by files.
To accomplish this I'm using org.craftercms.cstudio.publishing.processor.SearchAttachmentWithExternalMetadataPostProcessor
The first document I attached works fine but any other File is not being indexed with the metadata of the page.
This is the Reference list I'm using
<property name="referenceXpathList">
<list>
<value>//file/item/value</value>
</list>
</property>
Even though my XPath expression should match all file.item.value I'm just getting the first match.
SearchAttachmentWithExternalMetadataPostProcessor expects each XML document to just have one associated binary file. In most cases it makes sense because the XML document contains metadata that's just specific to that file. So if the XPath returns a list it will select the first one. You can always extend the processor and make it so that the same XML metadata is associated to different files.
I have created an XML file like the following
<monitor>
<widget name="Widgets/TestWidget1">
<state code="VIC" />
<state code="TAS" />
</widget>
<widget name="Widgets/TestWidget2">
<client code="someclient" />
</widget>
</monitor>
The name attribute of the <widget> tag tells the parser what widget to load (they are asp.net user controls).
I am trying to create a schema file for the above, the problem is that inside the <widget> the supported subtags are dependent on the name attribute. So TestWidget1 supports the <state> tag and TestWidget2 supports the <client tag.
Currently my XML Schema file just displays all possible <widget> subtags regardless of whether they are supported or not.
How can I write an XML schema file that will only allow specific subtags based on the name attribute? If this is not possible, what options do I have?
You have several options. The simplest and most direct is to re-think your problem a bit. If the legal content of element E1 and the legal content of element E2 are different, then the simplest design is to call them different things, because in XSD as in DTDs the legal content of an element depends on the element type name. A devil's advocate would ask you "if you want different kinds of widget to obey different rules, why are you telling the validator that they are the same kind of widget? Tell the validator the truth, by giving them different names. So don't call them and so on, call them and ."
In XSD 1.1 you can also use conditional type assignment or assertions to define constraints on the legal combinations of attributes and children, but not every schema-aware editor is going to have the chops necessary to analyse the conditional type assignment rules and attributes and understand what to prompt you with.
I have a domain model which is intended to generalise several source systems. As such, in certain cases the decision was made to overload data into new a generic field rather than to create several specific fields.
To account for this, when the source systems data is mapped onto the new domain model, I was hoping to record the source fieldname as an attribute, e.g.:
<Event>
<Description sourceField="subject">...</Description>
<Description sourceField="description">...</Description>
<Description sourceField="issue">...</Description>
<...>
</Event>
What would be the appropriate way to add such an attribute into the XSD? Would I need to specifically attach it to every such overloaded field, or is there a general way to allow an attribute across all elements?
Please don't point out that I should just add the extra fields into the domain model if I need to distinguish between the different data - the decision has been made, I just need to work around it!
Thanks in advance.
Not really.
If all your element declarations extend from a common base type definition, then you can add the attribute to the base.
If all your element declarations include an anyAttribute, you can make a global attribute definition for sourceField. Then the validator would at least allow your attribute but not require it. And if the anyAttribute is strict or lax the validator will make sure the attribute's content is valid.
Can I express this in an XSD?
For example:
One element is a required bool element named EmployedMoreThanThirteenWeeks and if the value is set to false I want the schema to require the existence of another element named EmploymentDate. And the other way around if the value is true then ideally the EmploymentDate element should be denied but I can accept it being optional.
No. An XSD just defines structure and data types, not relations. It is possible to add a key reference between elements but that won't prevent invalid nodes, just invalid values.
You can create an XSLT file (an XML Stylesheet) which will validate the XML file for you and thus generate a report of errors.
I think that XSD CANT do that, because the schemas verifies just an STRUCTURE (tree), and not VALUES (though you can check the value format).
You should consider other validation ways.