mysql - 使用 LINQ 构建动态查询

Question

我是rebuilding this website php/mysql 到 asp.net。我正在努力在页面标题中构建主卡片搜索表单。有一个文本输入、多个下拉菜单(全部指向不同的列)和一些条件搜索选项。

对于 mysql 版本，我能够使用条件来构建包含查询的字符串，然后执行它。

 //MySql/PHP example
 $query = "SELECT * FROM cards WHERE ";

    //Encounter_set 
if (isset($_GET['Encounter_Set']){
    $query.= "Encounter_Set=:Encounter_Set AND ";
    $queryArray['Encounter_Set'] = $_GET['Encounter_Set'];
}

 //radio statements
switch ($_GET['radio']) {
    case "All":     $query.= "(Title LIKE :terms OR Traits LIKE :terms OR Shadow_Text LIKE :terms OR Text LIKE :terms)";break;
    case "Title":   $query.= "(Title LIKE :terms)";break;
    case "Traits":  $query.= "(Traits LIKE :terms)";break;
    case "Text":    $query.= "(Shadow_Text LIKE :terms OR Text LIKE :terms)"; break;
    default:        $query.= "(Title LIKE :terms OR Traits LIKE :terms OR Shadow_Text LIKE :terms OR Text LIKE :terms)";
}

 //Finally
 $result = $db_con->prepare($query);

我该如何在 LINQ 中做到这一点？

Answer 1

using (var context = new MyDbContext())
{
    IQueryable<Card> query = context.Cards;
    if (!string.IsNullOrEmpty(Encounter_Set))
    {
        query = query.Where(c => c.Encounter_Set == Encounter_Set);
    }
    switch (radio)
    {
        default:
        case "All":
            query = query.Where(c => c.Title.Contains(terms)
                || c.Traits.Contains(terms)
                || c.Shadow_Text.Contains(terms)
                || c.Text.Contains(terms));
            break;
        case "Title":
            query = query.Where(c => c.Title.Contains(terms));
            break;
        case "Traits":
            query = query.Where(c => c.Traits.Contains(terms));
            break;
        case "Text":
            query = query.Where(c => c.Shadow_Text.Contains(terms)
                || c.Text.Contains(terms));
            break;
    }
    // ...
    return query.ToList(); // Execute the query
}