SQLKata动态子句

Question

我使用SQLKata在C#中构建了一个SQL语句，并在Github论坛上找到了一些代码，但是它没有编译。我需要帮助让它编译。

我在这行query.Where(q =>上收到两个错误

编译错误(第17行，col 16)：并非所有代码路径都返回类型为“System.Func”的lambda表达式中的值 编译错误(第17行，col 16)：无法将lambda表达式转换为“object”类型，因为它不是委托类型

class Group
{
   public List<Condition> Conditions {get; set;}
}

class Condition
{
   public string Field {get; set;}
   public string Operator {get; set;} 
   public object Value {get; set;}  
}

var query = new Query("Countries");

foreach(Group group in groups) 
{
    query.Where(q =>
    {
        foreach(Condition c in group.Conditions)
        {
            q.OrWhere(c.Field, c.Operator, c.Value);
        }
    });
}

.NET Fiddle是这里

Github后这里

更新我已经根据亚历克斯的答案更新了小提琴。我在寻找一个子句，因此预期的输出将OR语句用括号括起来。它现在大部分都像预期的那样工作，除了每个组都应该在自己的父类中，比如在下面

从下列国家选择*：(Group1Field1 = @p0或Group1Field2 > @p1或Group1Field3 < @p2或Group1Field4 = @p3)或(Group2Field1 = @p4或Group2Field2 >= @p5或Group2Field3 <= @p6)和Id = @p7

最终更新想出了答案。给出上述预期输出。谢谢。

var query = new Query("Countries");

    foreach (Group group in groups)
    {
        query.OrWhere(q => {
        foreach (Condition c in group.Conditions)
        {
            q.OrWhere(c.Field, c.Operator, c.Value);
        }
        return q;

        });

    }
query.Where("Id", "=", 10);

Answer 1

我更新了代码以修复错误。

var query = new Query("Countries");

foreach (Group group in groups)
{
    query.OrWhere(q => {
    foreach (Condition c in group.Conditions)
    {
        q.OrWhere(c.Field, c.Operator, c.Value);
    }
    return q;

    });

}
query.Where("Id", "=", 10);

Answer 2

试试这个：

List<Group> groups = new List<Group>
{
    new Group
    {
        Conditions = new List<Condition>
        {
            new Condition {Field = "Group1Field1", Operator = "=", Value="Group1Value1"},
            new Condition {Field = "Group1Field2", Operator = ">", Value="Group1Value2"},
            new Condition {Field = "Group1Field3", Operator = "<", Value="Group1Value3"},
            new Condition {Field = "Group1Field4", Operator = "=", Value="Group1Value4"}
        }
    },
    new Group
    {
        Conditions = new List<Condition>
        {
            new Condition {Field = "Group2Field1", Operator = "=", Value="Group2Value1"},
            new Condition {Field = "Group2Field2", Operator = ">=", Value="Group2Value2"},
            new Condition {Field = "Group2Field3", Operator = "<=", Value="Group2Value3"}
        }
    }
};

var query = new Query("Countries");
foreach (Group group in groups)
    foreach (Condition c in group.Conditions)
        query.OrWhere(c.Field, c.Operator, c.Value);

Console.WriteLine(new SqlServerCompiler().Compile(query).Sql);

产出如下：

SELECT * FROM [Countries] WHERE [Group1Field1] = @p0 OR [Group1Field2] > @p1 OR [Group1Field3] < @p2 OR [Group1Field4] = @p3 OR [Group2Field1] = @p4 OR [Group2Field2] >= @p5 OR [Group2Field3] <= @p6

.NET填充器

更新：

我检查了文档和测试，没有发现比下面更好的东西。要获得所需的输出，请使用：

foreach (var group in groups)
{
    if (!group.Conditions.Any())
        continue;

    if (group.Conditions.Count == 1)
    {
        var single = group.Conditions.Single();
        query.OrWhereRaw($"([{single.Field}] {single.Operator} ?)", single.Value);
        continue;
    }

    var first = group.Conditions.First();
    var last = group.Conditions.Last();
    var others = group.Conditions.Skip(1).Take(group.Conditions.Count - 2);

    query.OrWhereRaw($"([{first.Field}] {first.Operator} ?", first.Value);
    foreach (var c in others)
        query.OrWhere(c.Field, c.Operator, c.Value);
    query.OrWhereRaw($"[{last.Field}] {last.Operator} ?)", last.Value);
}

query.Where("Id", "=", 10);

而不是：

foreach (Group group in groups)
    foreach (Condition c in group.Conditions)
        query.OrWhere(c.Field, c.Operator, c.Value);

.NETFiddle