c# - 如果 with 关键字不好(对于 C#)，这是一个不错的选择吗？

Question

var insInvoice = new NpgsqlCommand(
    @"INSERT INTO invoice_detail(
    invoice_id,
    invoice_detail_id,
    product_id,
    qty,
    price,
    amount)
    VALUES (
    :_invoice_id,
    :_invoice_detail_id,
    :_product_id,
    :_qty,
    :_price,
    :_qty * :_price)", c);


with(var p = insInvoice.Parameters)
{
    p.Add("_invoice_id", NpgsqlDbType.Uuid, 0, "invoice_id");
    p.Add("_invoice_detail_id", NpgsqlDbType.Uuid, 0, "invoice_detail_id");
    p.Add("_product_id", NpgsqlDbType.Uuid, 0, "product_id");
    p.Add("_qty", NpgsqlDbType.Integer, 0, "qty");
    p.Add("_price", NpgsqlDbType.Numeric, 0, "price");
}

---

kludge:

for(var p = insInvoice.Parameters; false;)
{       
    p.Add("_invoice_id", NpgsqlDbType.Uuid, 0, "invoice_id");
    p.Add("_invoice_detail_id", NpgsqlDbType.Uuid, 0, "invoice_detail_id");
    p.Add("_product_id", NpgsqlDbType.Uuid, 0, "product_id");
    p.Add("_qty", NpgsqlDbType.Integer, 0, "qty");
    p.Add("_price", NpgsqlDbType.Numeric, 0, "price");      
}

Answer 1

当你有一个正确形式的“添加”方法时，你可以为参数使用一个集合初始化器:

var insInvoice = new NpgsqlCommand(sql)
{
    Parameters = 
    {
        { "_invoice_id", NpgsqlDbType.Uuid, 0, "invoice_id" },
        { "_invoice_detail_id", NpgsqlDbType.Uuid, 0, "invoice_detail_id" },
        { "_qty", NpgsqlDbType.Integer, 0, "qty" },
        { "_price", NpgsqlDbType.Numeric, 0, "price" }
    }
};

有关对象和集合初始值设定项的更多信息，您可以下载 C# in Depth 的第 8 章免费。