sql-server-2008 – 用于SQL Server 2008全文索引’包含’关键字

我以为在实现LinqToHql天生器类时我穷乏一些根基的对象.

我已行使此注册行使自界说方言乐成注册了SQL Server 2008包括的查询：

RegisterFunction("contains",new StandardSQLFunction("contains",null));

我只有一个类要查询全文索引：

public class SearchName
{
  public virtual Guid Id {get; set;}
  public virtual string Name {get; set;} // this is the search field
}

contains函数在HQL中正常事变：

var names = Session.CreateQuery("from SearchName where contains(Name,:keywords)")
                    .SetString("keywords","john")
                    .List();

而且天生的SQL是美满的：

select searchname0_.Id   as Id4_,searchname0_.Name as Name4_
from   Search_Name searchname0_
where  contains(searchname0_.Name,'john' /* @p0 */)

下一个挑衅是实现Linq到HQL天生器：

public class MyLinqtoHqlGeneratorsRegistry :
    DefaultLinqToHqlGeneratorsRegistry
    {
        public MyLinqtoHqlGeneratorsRegistry()
        {
            this.Merge(new ContainsGenerator());
        }
    }

    public class ContainsGenerator : BaseHqlGeneratorForMethod
    {
        public ContainsGenerator()
        {
            SupportedMethods = new[] {
                ReflectionHelper.GetMethodDefinition<SearchName>(d => d.Name.Contains(String.Empty))
          };
        }

        public override HqlTreeNode BuildHql(MethodInfo method,System.Linq.Expressions.Expression targetObject,ReadOnlyCollection<System.Linq.Expressions.Expression> arguments,HqlTreeBuilder treeBuilder,IHqlExpressionVisitor visitor)
        {
            return treeBuilder.MethodCall("contains",visitor.Visit(targetObject).AsExpression(),visitor.Visit(arguments[0]).AsExpression()
                );
        }
    }
}

挪用这样的要领：

var namesLinq = Session.Query<SearchName>().Where(x=> x.Name.Contains("john")).ToList();

不幸的是,这好像没有包围内置的Contains要领,而且天生的SQL是错误的：

select searchname0_.Id   as Id4_,searchname0_.Name as Name4_
from   Search_Name searchname0_
where  searchname0_.Name like ('%' + 'john' /* @p0 */ + '%')

是否无法包围默认的Contains要领,可能我只是犯了一个愚笨的错误？

PS – 我正在行使NHibernate 3.3.1.4000

办理要领

起首,我想法从我的设置中删除了注册码：

...
.ExposeConfiguration(cfg =>
     {
        cfg.LinqToHqlGeneratorsRegistry<MyLinqtoHqlGeneratorsRegistry>();
        ...
     }

其次,不要试图包围现有的Linq举动.我将Contains扩展要领移动到全文类.

第三,正确构建Hql树.

对付其他实行实现SQL 2008自由文本包括搜刮的人来说,这是完备的实现：

public static class DialectExtensions
    {
        public static bool Contains(this SearchName sn,string searchString)
        {
            // this is just a placeholder for the method info.  
            // It does not otherwise matter.
            return false;
        }
    }

    public class MyLinqtoHqlGeneratorsRegistry : DefaultLinqToHqlGeneratorsRegistry
    {
        public MyLinqtoHqlGeneratorsRegistry()
            : base()
        {
            RegisterGenerator(ReflectionHelper.GetMethod(() =>
                 DialectExtensions.Contains(null,null)),new ContainsGenerator());
        }
    }

    public class ContainsGenerator : BaseHqlGeneratorForMethod
    {
        string fullTextFieldName = "Name";

        public ContainsGenerator()
            : base()
        {
            SupportedMethods = new[] {
                ReflectionHelper.GetMethodDefinition(() =>
                DialectExtensions.Contains(null,null))
          };
        }

        public override HqlTreeNode BuildHql(MethodInfo method,IHqlExpressionVisitor visitor)
        {
            // cannot figure out how to interrogate the model class to get an 
            // arbitrary field name...
            // perhaps the RegisterGenerator() call above could be used to pass a
            // property name to the ContainsGenerator constructor?
            // in our case,we only have one full text searchable class,and its
            // full-text searchable field is "Name"
            HqlExpression[] args = new HqlExpression[2] {
                 treeBuilder.Ident(fullTextFieldName).AsExpression(),visitor.Visit(arguments[1]).AsExpression() 
                 };
            return treeBuilder.BooleanMethodCall("contains",args);
        }
    }

要使上述事变正常,您必需声明并行使自界说方言：

public class CustomMsSql2008Dialect : NHibernate.Dialect.MsSql2008Dialect
{
    public CustomMsSql2008Dialect()
    {
        RegisterFunction(
            "contains",null)
            );
    }
}

然后您可以这样行使新的包括搜刮：

var namesLinq = Session.Query<SearchName>().Where(x => x.Contains("john")).ToList();

…而获得的SQL是美满的！ (至少假如你只有一个表,你正在举办全文搜刮)

编辑：更新实现支持高出一个FULLTEXT’包括’搜刮每个查询.

（编辑：湖南网）

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