Net class name embedded in the where clause will be translated to its discriminator value. All xml mappings should declare the xml namespace shown. As always you can download the code for the sample here. Inheritance mapping strategies in fluent nhibernate codeproject. So a long time ago james kovacs posted a article about getload polymorphism with nhibernate, which was cool and all but i always wanted to know how to map it all in fluent nhibernate. In fluent, subclasses are mapped by inheriting from the same subclassmap as in single table strategy. The term objectrelational mapping orm refers to the technique of mapping a data representation from an object. Since version 6, entity framework code first allows the injection of custom conventions. Likewise, the special property class accesses the discriminator value of an instance in the case of polymorphic persistence. You can see a comparison of the old and new syntaxes. I recently posted about enumeration classes, and how i like to use them as a sort of enumerations with behavior.
Using discriminator with fluent nhibernate stack overflow. Custom entity framework code first convention for discriminator values since version 6, entity framework code first allows the injection of custom conventions. The tricky thing is, the join table has a column that determines what type of relationship it is. A discriminator is a key to uniquely identify the base type of the class hierarchy. Theres one thing i think would make a great addition to these posts insight. Im trying to map a joinedsubclass scenario using fluent nhibernate. Xml is not very wrist friendly and also not very readable.
I need to have employeetype discriminator column for selectinsertupdate. When you use a discriminator column, that is, a column that holds a value that tells entity framework what type the row refers to, or what restriction it shall use when querying the entity, you cannot map this column as a property in your entity. The following is what youd use inside the constructor of your book mapping cfg fluently configuring the nhibernate. Among other things, the reference data table contains discriminator, code and value columns. We will map employee and manager entities using single table per class hierarchy mapping stretegy. Now there is a third alternative to define the mapping of entities to database the fluent nhibernate api. Its a fluent interface that allows you to map your entities completely in code, with all the compiletime safety and refactorability that brings the getting started guide has a good introduction to mapping with the fluent interface, and the detail provided here builds upon that introduction.
Using the same samples that i used in table per class hierarchy inheritance mapping with fluent nhibernate and table per subclass inheritance mapping with fluent nhibernate i will show you the changes. We cannot use discriminatesubclassesoncolumnusergroup. You can configure the name and type of the discriminator column and. Aaron jensen, alexander gross, andrew stewart, barry dahlberg, bobby johnson, brian donahue, cameron harris, chad myers. If you are using the fluent mapping api you can have a look at this help article.
The getting started guide has a good introduction to mapping with fuent fluent interface. I wonder if anyone has found a way of telling fnh what the discriminator value is for the sub classes. Not every enumeration should be replaced with a class, but that pattern helps quite a bit when i find a lot of switch statements concerning my enumeration. Only the method used differs instead of discriminatorvalue, were using keycolumn method with column name in the parameter required, no default value. Entity in the namespace somemodule now i obviously do. Fluent nhibernate will see that your id property has a type of int, and itll automatically. Table per class hierarchy inheritance mapping with fluent. Fluent, xmlless, compile safe, automated, conventionbased mappings for. With the help of fluent nhibernate, you can write mappings in. How can i use fluent nhibernate to discriminate on a column of a. Each element is displayed in a table that enumerates available elements and attributes, with several columns denoting the level of support for each element or attribute in fnh.
Conventions interfaces to define conventions used for auto and fluent mappings. Contribute to fluentnhibernatefluentnhibernate development by. The actual schema definition may be found in the src\ nhibernate mapping. I have a discriminator column in the which i need to use for select insert and update. Solved nhibernate mapping with propertyref on base. A fluent interface to nhibernate part 1 nhibernate. Fluent nhibernate s interface is designed for discoverability. Updated nhibernate and fluent nhibernate assemblies to latest.
I tried with other inheritance mapping models but i cant figure out how to point on the base class identifier field with a discriminator where clause. Nhibernate s implementation of table per subclass does not require a discriminator column. Hiibernate 5 generates dtype name for the discriminator column. You may download log4net from, or install it with nuget. To quote the nhibernate documentation youll quickly get used to these lambdas, as theyre used everywhere in fluent nhibernate. Grouptype among many other good reasons, discriminator is managed by.
Samples blog article to read more about this application and download it. It seems nhibernate doesnt use the discriminator to find the row with the matching identifier. Nhibernate mapping a single domain model to multiple physical data models time to read 15 min 2809 words a while ago i sat down and talked with a colleague about the entity framework, he raved about how important the separation of the logical model from the physical one is. Updates to subclass and joinedsubclass mapping in fluent. How to force nhibernate to use discriminator while. Fluent nhibernate mappingdiscriminator oracle community. How to force nhibernate to use discriminator while fetching entities for single table per class hierarchy mapping. Fluent nhibernate s equivalent for table per class.
Reason for this is lack of discriminatorvalue setting method in classinstance class and. I think this scenario is quite exotic why do we need a discriminator column if we have separate tables. These conventions define rules that will be applied by default to all mapped entities and properties, unless explicitly changed. Mapping messagestatus has to be based on the fact that each entity will have a value discriminator that will cause nhibernate to instantiate this or another descendent of messagestatus base abstract class. Its discriminator, id, and number properties are value typed, and we use the builtin nhibernate mapping types to specify the conversion. Fluent nhibernate subclass syntax changes james gregory. In one table per class hierarchy scheme, we store all the class hierarchy in a single sql table. Showing the mappings and sql in a very manuallike way is sure great but i wish you took it one step further and talked about nonobvious strengths and weaknesses of each approach. Recently xanatos in a comment to one of my mappingbycode series post asked how to implement hybridmode inheritance with both table per subclass and discriminator columns using mappingbycode. Notice that the discriminator value was not added to the query. To start with weve mapped the id column, and told fluent nhibernate that its actually an identifier. I worked it out at the time but i guess its taken me 7 months to write it down. Fluent nhibernate subclass syntax changes 05 jan 2009. Strategies and discriminators in nhibernate 27 august, 2008.
Ive just committed a breaking change to fluent nhibernate as of r184, which i thought id document here for anyone interested. Nhibernate mapping a single domain model to multiple. Fluent mapping fluentnhibernatefluentnhibernate wiki github. I have a class entity defined in the namespace core, and a class subclass. Fluent, xmlless, compile safe, automated, conventionbased mappings for nhibernate. Please provide your whole solution so i can troubleshoot. Having recently discovered discriminators, i applied the discriminator tag to.
Fluent nhibernate is another way of mapping or you can say it is an alternative to nhibernate s standard xml mapping files. How to add a primary key with fluent api entity framework ef 4. For example if you wanted to specify dochmentation cascade flhent youd use the cascade property. Nhibernate is an objectrelational mapping tool for. In this chapter, we will be covering fluent nhibernate. How to include the fluent nhibernate discriminator column. Following are the advantages and disadvantages of one table per class hierarchy scheme. The discriminator column stores the name of the class and is used by fluent nhibernate to determine which subclass to instantiate, the value column is the full name of the reference data item, and the code column is the abbreviated. Fluent mapping is the namesake mapping style that fluent nhibernate uses. Nhibernate may not be the best solution for datacentric applications that only use storedprocedures to implement the business logic in the database, it is most useful. How could i have possibly used vs as long as i have nhiberhate never noticed its namespace resolution support. Using an nhibernate discriminator with a stored procedure recently i needed to split the results of a stored procedure into one of two classes based on one of the columns using nhibernate. The optional column name portions of the mapping are most helpful in. Contribute to vladynev fluenthibernate development by creating an account on github.
Inheritance mapping strategies in fluent nhibernate. Is there a way to map these legacy tables with nhibernate. Its a fluent interface that allows you to map your entities completely in code, with all the compiletime safety and refactorability that brings the getting started guide has a good introduction to mapping with the fluent interface. First up is using a single table, mapping them to multiple classes, this is done using a discriminator. Understanding the nhibernate type system dzone database. The purpose of this page is to provide a complete list of all of the elements defined by the nhibernate mapping schema. Previous values of properties of references between entities reappear if the. Other objectrelational mappers use a different implementation of table per subclass that requires a type discriminator column in the superclass table. Fluent mapping fluentnhibernatefluentnhibernate wiki.
Class mapping can have discriminator value as well as subclass, but there is no way to specify it in automapping class convention inherited from iclassconvention. But from what i can see, discriminator value is inherited by the mapping of derived class and fluent mistakenly puts it. Once youve read that then you should be able to find a bit more detail here. Handle discriminator data when importing existing visual studio projects. Getting started fluentnhibernate fluent nhibernate wiki. Contribute to vladynev fluent hibernate development by creating an account on github. I need to set more than one discriminate values for parent class. The x in this example is an instance of employee that fluent nhibernate uses to retrieve the property details from, so all youre really doing here is telling it which property you want your id to be.
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