XML mapping tags for entities and databases-nhibernate getting started to master series 6__ databases

NHibernate development, must pass phase: Need entity and XML mapping, this section focuses on this piece of content.

For novice developers, how to map the database and XML mapping, is not cut, the following start introduction:

One: What is nhibernate mapping?

In fact, it is in the database and entities, put more than one external storage media XML, to link the relationship between the two, when the database changes, by modifying the XML configuration, to achieve mapping of the switch, so no need to modify the code.


Let's look at a simple XML that maps between databases and entities:

<?xml version= "1.0" encoding= "Utf-8"?>

<class name= "class name" table= "table name" lazy= "true" >
<id name= "id" column= "id" type= "int" >
<generator class= "Assigned"/>
</id>
<property name= "Name" type= "string" >
<column name= "name" length= "Wuyi"/>
</property>

</class>

It is also very simple, basically because there are too many tables or fields, this kind of mapping usually needs to use the NHibernate tool to build.

Two: nhibernate mapping label

is actually an explanation of the various meanings of the mapping XML above:

1: We first look at the root node, of course, the following content than the above: hibernate-mapping tags

Schema= "schemaName" Database schema name

Default-cascade= "None|save-update" cascading style (default none)

auto-import= whether the "True|false" query statement can use a non-fully qualified name

DLL name of class for assembly= "AssemblyName" Mapping file

namespace name of the class for the Namespace= "namespace" mapping file

/>

2:nhibernate class Label


<class
Name= the full name of the "ClassName" class.
Table= the "tablename" database table name.
Discriminator-value= "Discriminator_value" distinguishes the distinguished values of different subclass values, using polymorphic behavior.
Mutable= whether an instance of the "True|false" class is variable.
Schema= "owner" overrides the schema name specified in the root element.
Proxy= the name of the "Proxyinterface" proxy class.
Dynamic-update= "True|false" dynamically generates an UPDATE statement.
Dynamic-insert= "True|false" dynamically generates INSERT statements.
Select the Select-before-update= "True|false" before updating
polymorphism= "implicit|explicit" implicit query or explicit query.
where= "arbitrary SQL Where condition" attaches the Where condition, which is automatically added in the statement.
Persister= "Persisterclass" Custom Iclasspersister.
Batch-size= "N" batch read quantity [Default 1].
optimistic-lock= the "None|version|dirty|all" locking policy.
Whether the lazy= "True|false" is delayed loading.
Abstract= "True|false" is an abstract class.
/>

3:nhibernate ID Label

<id

Name= the "PropertyName" Entity property name.
Type= "TypeName" NHibernate type name
column= the "column_name" database field name.
Unsaved-value= the "Any|none|null|id_value" instance is not saved.
Access= "field|property|nosetter| ClassName "NHibernate the policy used to access property values.
<generator class= "Generatorclass"/>
</id>

4:nhibernate Property Label

<property
Name= "PropertyName"Entity attribute name
Column= "column_name"database field Name 。
Type= "TypeName"NHibernate type name 。
Update= "True|false" contains this field if it is update.
Insert= "True|false" contains the field if it is insert.
Formula= "arbitrary SQL expression" SQL expression that defines the value of this computed property
Access= "field|property| ClassName "NHibernate policy for accessing property values
optimistic-lock= "True|false" optimistic locking strategy
generated= whether the "Never|insert|always" property value is generated by the database
/>

Three: NHibernate mapping type

1:nhibernate Value type Mappings

nhibernate Type	. NET Type	Database Type	Notes
Ansichar	System.Char	Dbtype.ansistringfixedlength-1 Char
Boolean	System.Boolean	Dbtype.boolean	The default value when no type attribute is specified.
Byte	System.Byte	Dbtype.byte	The default value when no type attribute is specified.
Char	System.Char	Dbtype.stringfixedlength-1 Char	The default value when no type attribute is specified.
Datetime	System.DateTime	Dbtype.datetime-ignores the milliseconds	The default value when no type attribute is specified.
Decimal	System.Decimal	Dbtype.decimal	The default value when no type attribute is specified.
Double	System.Double	Dbtype.double	The default value when no type attribute is specified.
Guid	System.Guid	Dbtype.guid	The default value when no type attribute is specified.
Int16	System.Int16	Dbtype.int16	The default value when no type attribute is specified.
Int32	System.Int32	Dbtype.int32	The default value when no type attribute is specified.
Int64	System.Int64	Dbtype.int64	The default value when no type attribute is specified.
Persistentenum	System.Enum	Potential type corresponding to DbType	You do not have to specify type= "Persistentenum" in the mapping file. Instead, the full name of the enumerated assembly is provided, allowing the nhibernate to guess the type with reflection. The potential types used by enumerations determine the appropriate dbtype.
Single	System.Single	Dbtype.single	The default value when no type attribute is specified.
Ticks	System.DateTime	Dbtype.int64	Type= "Ticks" must be specified.
TimeSpan	System.TimeSpan	Dbtype.int64	The default value when no type attribute is specified.
Timestamp	System.DateTime	Dbtype.datetime-Depends on database support	Type= "Timestamp" must be specified.
TrueFalse	System.Boolean	Dbtype.ansistringfixedlength-a character, ' Y ' or ' N '	Type= "TrueFalse" must be specified.
Yesno	System.Boolean	Dbtype.ansistringfixedlength-a character, ' Y ' or ' N '	Type= "Yesno" must be specified.

2: NHibernate Apply Type mappings

NHibernate Type	. NET Type	Database Type	remarks
Ansistring	System.String	Dbtype.ansistring	Type= "Ansistring" must be specified.
CultureInfo	System.Globalization.CultureInfo	Dbtype.string-5 characters indicating culture (culture)	The default value when no type attribute is specified.
Binary	System.byte[]	Dbtype.binary	The default value when no type attribute is specified.
Type	System.Type	Dbtype.string Save the application's centralized qualified name.	The default value when no type attribute is specified.
String	System.String	Dbtype.string	The default value when no type attribute is specified.

3: NHibernate binary Type mappings

NHibernate Type	. NET Type	Database Type	remarks
Stringclob	System.String	Dbtype.string	Type= "Stringclob" must be specified. The entire field is readable in memory.
Binaryblob	System.byte[]	Dbtype.binary	Type= "Binaryblob" must be specified. The entire field is readable in memory.
Serializable	Any System.Object must annotate a serializable label	Dbtype.binary	Type= "Serializable" should be specified. If you cannot find the NHibernate type for a property, this is the last type to rely on.

NHibernate Summary:

This section mainly introduces the knowledge of entity and XML mapping in NHibernate development.

The

is also a verifiable document, in the development process can be a lot of reference to help you develop.