該查詢如何轉換爲動態Linq表達式？

Question

select * 
    from bis.CompanyInfo ci 
    where ci.IsDeleted = 0 
     and ci.IsBindingApproved = 1 
     and ((ci.[Name] like N'%blah%' 
      or ci.CityName like N'%blah%') 
      or (ci.[Name] like N'%groupe%' 
       or ci.CityName like N'%groupe%')) 

考慮到「blah」和「groupe」是我必須搜索的關鍵字。要搜索的關鍵字數量是可變的，這就是它需要動態變化的地方。所以，我可以有任意數量的關鍵字來查找從0到數百。

任何幫助表示讚賞！ =）

Answer 1

好像有一個命令或像加入內部過濾器一樣。讓我們把這個代碼作爲我的CreateFilter方法的初始。

private Expression<Func<CompanyInfo, bool>> 
    CreateFilter(SearchCriterion criterion) { 
    var outerFilter = PredicateBuilder.True<CompanyInfo>(); 
    outerFilter = outerFilter.And(ci => !ci.IsDeleted && ci.IsBindingApproved); 

    var innerFilter = PredicateBuilder.False<CompanyInfo>(); 
    foreach(var keyword in criterion.Keywords) { 
     var w = keyword; 
     innerFilter = innerFilter.Or(ci => ci.Name.Contains(w) 
             || ci.CityName.Contains(w)) 
    } 
    outerFilter = outerFilter.And(innerFilter); 

    if (criterion.HasCityName) 
     outerFilter = outerFilter.And(ci => 
      ci.CityName.Contains(criterion.CityName)); 

    // Other similar filter here... 

    return outerFilter; 
} 

這並沒有返回正確的結果。然後，根據這篇文章：LINQ: Complicated Advanced Search with Dynamic Where Clause，我更改了我的代碼。

private Expression<Func<CompanyInfo, bool>> 
    CreateFilter(SearchCriterion criterion) { 
    var innerFilter = PredicateBuilder.False<CompanyInfo>(); 
    foreach(var keyword in criterion.Keywords) { 
     var w = keyword; 
     innerFilter = innerFilter.Or(ci => ci.Name.Contains(w) 
             || ci.CityName.Contains(w)) 
    } 
    var outerFilter = PredicateBuilder.True<CompanyInfo>(); 
    outerFilter = outerFilter.And(ci => !ci.IsDeleted && ci.IsBindingApproved); 

    if (criterion.HasCityName) 
     outerFilter = outerFilter.And(ci => 
      ci.CityName.Contains(criterion.CityName)); 

    // Other similar filter here... 

    // Here, we want to include the filter on keywords only when there are 
    // some provided with the search. 
    // Otherwise, the result of the And(innerFilter) with no keywords 
    // will always be 'false' and return no results though other criterion 
    // might be met such as the CityName and whatever the others are. 
    if (criterion.HasKeywords) outerFilter = outerFilter.And(innerFilter); 

    return outerFilter; 
} 

它完美地工作！我不明白爲什麼結果是完美的，因爲看起來過濾器的順序會影響結果，這對我很有用。

Answer 2

var result = (from oCompanyInfo as CompanyInfo in CompanyInfoList 
      where oCompanyInfo.IsDeleted = 0 and oCompanyInfo.IsBindingApproved = 1 and    
      (Name.Contains("blah") or oCompanyInfo.CityName.Contains("blah") or 
      oCompany.Name.Contains("groupe") or oCompany.CityName.Contains("groupe")) 
      select oCompanyInfo).ToList() 

在那裏，你可以取代「嗒嗒」或「GROUPE」到txtCompanyName.Text和txtCityName.text（如果過濾文本是一個文本框）