为了构建动态查询,我将使用条件 API。这使得动态查询更加稳定,因为您不需要字符串操作来构建它。
ICriteria query = Session.CreateCriteria(typeof(Recipe), "r")
.CreateCriteria("Ingredients", "i", JoinType.InnerJoin)
.Add(
Expression.Disjunction() // OR
.Add(Expression.Like("i.IngredientName", "%pasta%"))
.Add(Expression.Like("i.IngredientName", "%wine%"))
.Add(Expression.Like("r.RecipeTitle", "%pasta%"))
.Add(Expression.Like("r.RecipeTitle", "%wine%")));
List<Recipe> result = query.List<Recipe>();
Edit:
对于急切加载,您可以设置 fetch-mode:
ICriteria query = Session.CreateCriteria(typeof(Recipe), "r")
.SetFetchMode("Images", FetchMode.Join)
.SetFetchMode("Comments", FetchMode.Join)
.SetFetchMode("Ingredients", FetchMode.Join)
但我不会这样做因为你得到的结果乘以图像、评论和成分的数量。因此,如果您有 4 张图片、2 条评论和 12 种成分,您将获得 96 次食谱。您没有意识到这一点,因为 NHibernate 将这些东西重新组合在一起,但它会在应用程序和数据库之间产生流量。因此最好让 NHibernate 通过单独的查询来加载它。
又一编辑显示动态查询组合。
// filter arguments, all are optional and should be omitted if null
List<string> keywords;
TimeSpan? minCookingTime;
TimeSpan? maxCookingTime;
int? minRating;
int? maxRating;
ICriteria query = Session.CreateCriteria(typeof(Recipe), "r");
if (keyword != null)
{
// optional join
query.CreateCriteria("Ingredients", "i", JoinType.InnerJoin);
// add keyword search on ingredientName and RecipeTitle
var disjunction = Expression.Disjunction();
foreach (string keyword in keywords)
{
string pattern = String.Format("%{0}%", keyword);
disjunction
.Add(Expression.Like("i.IngredientName", pattern))
.Add(Expression.Like("r.RecipeTitle", pattern));
}
query.Add(disjunction)
}
if (minCookingTime != null)
{
query.Add(Expression.Ge(r.CookingTime, minCookingTime.Value));
}
if (maxCookingTime != null)
{
query.Add(Expression.Le(r.CookingTime, maxCookingTime.Value));
}
if (minRating != null)
{
query.Add(Expression.Ge(r.Rating, minRating.Value));
}
if (maxRating != null)
{
query.Add(Expression.Le(r.Rating, maxRating.Value));
}