使用 MultiValueDictionary 而不是带有 NHibernate.Criterion.Restrictions 的字典

Question

目前，我有这段代码，它可以工作，获取食物列表：

var myDictionary = new System.Collections.Generic.Dictionary<string, object>();
myDictionary .Add("RefId",1);
myDictionary.Add("Type", "fruit");
var foodList = this.factoryService.GetMyService()
                    .GetByCriteria(sortOrder, NHibernate.Criterion.Restrictions.AllEq(myDictionary));

我想使用MultiValueDictionary来收集不止一种类型。

var multiValueDictionary = new System.Collections.Generic.MultiValueDictionary<string, object>();
multiValueDictionary.Add("RefId",1);
multiValueDictionary.Add("Type", "fruit");
multiValueDictionary.Add("Type", "vegetable");
multiValueDictionary.Add("Type", "fungus");

var foodList = this.factoryService.GetMyService()
                    .GetByCriteria(sortOrder, NHibernate.Criterion.Restrictions.AllEq(multiValueDictionary));

最后一行没有编译，因为 MultiValueDictionary 没有实现 IDictionary，给出了错误：

Error CS1503 Argument 1: cannot convert from 'System.Collections.Generic.MultiValueDictionary' to 'System.Collections.IDictionary'

我该怎么做？

Answer 1

AllEq implementation 就是：

/// <summary>
/// Apply an "equals" constraint to each property in the key set of a IDictionary
/// </summary>
/// <param name="propertyNameValues">a dictionary from property names to values</param>
/// <returns></returns>
public static AbstractCriterion AllEq(IDictionary propertyNameValues)
{
    Conjunction conj = Conjunction();

    foreach (DictionaryEntry item in propertyNameValues)
    {
        conj.Add(Eq(item.Key.ToString(), item.Value));
    }

    return conj;
}

因此，对于您的多值案例，您可以停止将其放入字典中，然后手动添加：

var myDictionary = new Dictionary<string, object>();
myDictionary.Add("RefId", 1);

var filter = (Conjunction)Restrictions.AllEq(myDictionary);
filter.Add(Restrictions.In("Type", new [] {"fruit", "vegetable", "fungus"});

var foodList = this.factoryService.GetMyService()
    .GetByCriteria(sortOrder, filter);

当然，如果你现在只有RefId可以放入你的字典，最好简化它：

var filter = Restrictions.Conjunction();
filter.Add(Restrictions.Eq("RefId", 1));
filter.Add(Restrictions.In("Type", new [] {"fruit", "vegetable", "fungus"}));

var foodList = this.factoryService.GetMyService()
    .GetByCriteria(sortOrder, filter);

现在，如果您想要 AllIn 处理多值，请对其进行编码：

public static AbstractCriterion AllIn<TValue>(
    MultiValueDictionary<string, TValue> propertyNameValues)
{
    var conj = Restrictions.Conjunction();

    foreach (KeyValuePair<TKey, IReadOnlyCollection<TValue>> item in propertyNameValues)
    {
        if (item.Value.Count > 1)
        {
            conj.Add(Restrictions.In(item.Key, item.Value.ToArray()));
        }
        else
        {
            conj.Add(Restrictions.Eq(item.Key, item.Value.FirstOrDefault()));
        }
    }

    return conj;
}

使用 MultiValueDictionary 而不是带有 NHibernate.Criterion.Restrictions 的字典

Use MultiValueDictionary instead of Dictionary with NHibernate.Criterion.Restrictions

c#

nhibernate

multi-value-dictionary