ISelect 动态 Include 代码实现

[2881099]

当 T 未知的时候，可以使用该方法传入属性字符串

fsql.Select<Tag>()
    .Include(a => a.Parent.Parent)
    .ToList();

fsql.Select<Tag>()
    .Include("Parent.Parent")
    .ToList();

SQL：

SELECT ...
FROM [Tag] a 
LEFT JOIN [Tag] a__Parent ON a__Parent.[Id] = a.[Parent_id] 
LEFT JOIN [Tag] a__Parent__Parent ON a__Parent__Parent.[Id] = a__Parent.[Parent_id] 

/// <summary>
/// 动态 Include，如：fsql.Select&lt;Tag&gt;().Include("Parent.Parent").ToList();
/// </summary>
/// <typeparam name="T1"></typeparam>
/// <param name="select"></param>
/// <param name="navigateSelector"></param>
/// <returns></returns>
public static ISelect<T1> Include<T1>(this ISelect<T1> select, string navigateSelector) where T1 : class
{
    var s0p = (select as Select0Provider);
    var parmExp = Expression.Parameter(typeof(T1), s0p._tables[0].Alias);
    var currentType = typeof(T1);
    Expression currentExp = parmExp;
    foreach (var tmp1 in navigateSelector.Split('.'))
    {
        if (s0p._commonUtils.GetTableByEntity(currentType).Properties.TryGetValue(tmp1.Trim(), out var prop) == false)
            throw new ArgumentException($"{currentType.DisplayCsharp()} 无法找到属性名 {tmp1}");
        currentType = prop.PropertyType;
        currentExp = Expression.MakeMemberAccess(currentExp, prop);
    }
    if (currentExp == parmExp) return select;
    var navigateSelectorLambda = Expression.Lambda(
        typeof(Func<,>).MakeGenericType(typeof(T1), currentType),
        currentExp,
        parmExp);
    select.GetType().GetMethod("Include").MakeGenericMethod(currentType)
        .Invoke(select, new object[] { navigateSelectorLambda });
    return select;
}