如何在 Mysql Connector/NET 中省略对 SqlNullValueException 的检查

发布于 2024-10-13 21:52:43 字数 851 浏览 1 评论 0原文

从读取器读取数据时，我必须检查数据库中允许空值的每个参数是否抛出 NullValueException。特别是我必须使用单独的 try/catch 检查每个值，因为我仍然想解析第一个值为空的下一个值。在 C# 中，某些类有一个 tryParse(key, out value) 函数，成功时返回一个布尔值，但我没有在 Connector/NET 中找到它。有什么办法可以缩短以下语句吗？

Product product;
try {
    product = new Product(
        reader.GetString("product_id"),
        reader.GetDateTime("starttime")
        );
    try {
        product.EndTime = reader.GetDateTime("endtime");
    } catch (System.Data.SqlTypes.SqlNullValueException) { }
    try {
        product.Description = reader.GetString("description");
    } catch (System.Data.SqlTypes.SqlNullValueException) { }
    try {
        product.Type = reader.GetString("type");
    } catch (System.Data.SqlTypes.SqlNullValueException) { }
} catch (MySqlException ex) {
    throw ex;
} catch (Exception ex) {
    throw ex;
}

原文

When reading data from the reader I have to check each parameter that allows for null values in the database whether it is threw a NullValueException. Especially I have to check each value with a separate try/catch because I still want to parse the next value it the first one was null. In C# some classes have a tryParse(key, out value) function, which returns a boolean on success, but I didn't find it for Connector/NET. Is there any way to shorten the following statements?

Product product;
try {
    product = new Product(
        reader.GetString("product_id"),
        reader.GetDateTime("starttime")
        );
    try {
        product.EndTime = reader.GetDateTime("endtime");
    } catch (System.Data.SqlTypes.SqlNullValueException) { }
    try {
        product.Description = reader.GetString("description");
    } catch (System.Data.SqlTypes.SqlNullValueException) { }
    try {
        product.Type = reader.GetString("type");
    } catch (System.Data.SqlTypes.SqlNullValueException) { }
} catch (MySqlException ex) {
    throw ex;
} catch (Exception ex) {
    throw ex;
}

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蓝眸 2024-10-20 21:52:43

我通常将这种模式与 SqlDataReader 一起使用，我想它应该与 MySQL Connector/Net 相同。

product.EndTime = reader["endtime"] as DateTime? ?? DateTime.MinValue;
product.Description = reader["description"] as string;
product.Type = reader["type"] as string;

I usually use this pattern with SqlDataReader, I imagine it should be the same with MySQL Connector/Net.

product.EndTime = reader["endtime"] as DateTime? ?? DateTime.MinValue;
product.Description = reader["description"] as string;
product.Type = reader["type"] as string;

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