blocks|key|3722575|text|空引用异常到底发生在哪里？_repo为空吗？|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3722576|尝试并仔细检查“Client”表中没有任何不可为空的列，并且没有设置任何值。|3722577|还要确保您的PK被正确处理(检查您是否具有[Property.IsForeignKey=true;]属性)|3722578|entityMap^0|D|5|0|0|L|T|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|K|$]]

Where does the null reference exception actually happen? Is <code>_repo</code> null?

Try and double check that you don’t have any columns in the “Client” table which are not nullable and you don’t set any value.

Also make sure you PK is handled correctly (check you have the <code>[Property.IsForeignKey=true;]</code> attribute)

blocks|key|1406567|text|您是否已签入NullReferenceException+(文件菜单)调试->异常(按Find并键入NullReferenceException，然后按OK)？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1406568|我下载了SubSonic代码并将其用作我的项目的引用，异常在SubSonic.Core\Repository\SubSonicRepository.cs:209中抛出，因为在第208行没有检查prop是否为null，并且如第213行所示，任何异常都会被接受。|offset|length|style|BOLD|1406569|发生的情况是，在上述对话框中选中的所有异常都会中断visual+studio。因此，在某种程度上，这是代码的预期行为。|1406570|实际上是什么原因导致prop变为null，在我的例子中，表字段名是小写的，但属性实际上是正确大小写的。|1406571|从立即开始|1406572|tbl.PrimaryKey.Name
"playerinformationid"

item.GetType().GetProperties()++
{System.Reflection.PropertyInfo[11]}++
++++[0]:+{System.Collections.Generic.IList`1[SubSonic.Schema.IColumn]+Columns}++
++++//+*snip*++
++++[5]:+{Int32+PlayerInformationid}
++++//+*snip*

item.GetType().GetProperty("PlayerInformationid")
{Int32+PlayerInformationid}+//+Works!

item.GetType().GetProperty(tbl.PrimaryKey.Name)
null|code-block|syntax|javascript|1406573|我把这段代码拼凑在一起就是为了“让它正常工作”(警告:新手在3.5版本)|1406574|-var+prop+=+item.GetType().GetProperty(tbl.PrimaryKey.Name);
%2Bvar+lowerCasedPrimaryKeyName+=+tbl.PrimaryKey.Name.ToLowerInvariant();
%2Bvar+prop+=+item.GetType().GetProperties().First<System.Reflection.PropertyInfo>(x+=>+x.Name.ToLowerInvariant()+==+lowerCasedPrimaryKeyName);|1406575|entityMap|0|LINK|mutability|MUTABLE|url|http://github.com/subsonic/SubSonic-3.0/blob/db485410a72f6d49cd83280f197728706f0ded48/SubSonic.Core/Repository/SubSonicRepository.cs#L209^0|0|2O|4|U|1E|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|15|8|@$D|16|E|17|F|G]]|9|@$D|18|E|19|1|1A]]|A|$]]|$1|H|3|I|5|6|7|1B|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|1C|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|1D|8|@]|9|@]|A|$]]|$1|N|3|O|5|P|7|1E|8|@]|9|@]|A|$Q|R]]|$1|S|3|T|5|6|7|1F|8|@]|9|@]|A|$]]|$1|U|3|V|5|P|7|1G|8|@]|9|@]|A|$Q|R]]|$1|W|3|-4|5|6|7|1H|8|@]|9|@]|A|$]]]|X|$Y|$5|Z|10|11|A|$12|13]]]]

Do you have NullReferenceException Checked in (file menu) Debug -> Exceptions (press Find and type NullReferenceException, press OK)?

I downloaded the SubSonic code and used it as reference for my project, the exception is thrown in <a href="http://github.com/subsonic/SubSonic-3.0/blob/db485410a72f6d49cd83280f197728706f0ded48/SubSonic.Core/Repository/SubSonicRepository.cs#L209" rel="nofollow noreferrer">SubSonic.Core\Repository\SubSonicRepository.cs:209</a> because prop is not checked for null at line 208, and any exceptions are swallowed as evidenced by line 213.

What happens is visual studio breaks on all the exceptions checked in the mentioned dialog. So in one way, this is the expected behaviour from the code.

What actually causes prop to become null, in my case, the table field name is lower-case, but the property is actually cased properly.

From Immediate:

<pre><code>tbl.PrimaryKey.Name
"playerinformationid"

item.GetType().GetProperties() 
{System.Reflection.PropertyInfo[11]} 
 [0]: {System.Collections.Generic.IList`1[SubSonic.Schema.IColumn] Columns} 
 // *snip* 
 [5]: {Int32 PlayerInformationid}
 // *snip*

item.GetType().GetProperty("PlayerInformationid")
{Int32 PlayerInformationid} // Works!

item.GetType().GetProperty(tbl.PrimaryKey.Name)
null
</code></pre>

I hacked this together to "just make it work" (Warning: newbie at 3.5 stuff)

<pre><code>-var prop = item.GetType().GetProperty(tbl.PrimaryKey.Name);
+var lowerCasedPrimaryKeyName = tbl.PrimaryKey.Name.ToLowerInvariant();
+var prop = item.GetType().GetProperties().First&lt;System.Reflection.PropertyInfo&gt;(x =&gt; x.Name.ToLowerInvariant() == lowerCasedPrimaryKeyName);
</code></pre>

blocks|key|5190505|text|你的桌子有PrimaryKey吗？听起来不像是这样。如果不是，这就是你的问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5190506|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Does your table have a PrimaryKey? It doesn't sound like it does. If not - this is your problem.

blocks|key|1406599|text|我遇到了类似的问题，代码与以下代码类似：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1406600|var+pending+=+myTable.SingleOrDefault(x+=>+x.Id+==+1);
if+(pending+==+null)
++++pending+=+new+myTable();

pending.Id+=+1;
pending.MyDate+=+DateTime.Now;
pending.MyString+=+someString;
pending.Save();|code-block|syntax|javascript|1406601|这在我第一次在空表上运行时有效，但在第二次更新时不起作用。我在subsonic库中的某个地方得到了一个空引用异常。按照Rob的建议，解决方案是添加一个主键。|1406602|我想我应该提一下(谢谢Rob)。|1406603|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I had a similar problem, with code not unlike the following:

<pre><code>var pending = myTable.SingleOrDefault(x =&gt; x.Id == 1);
if (pending == null)
 pending = new myTable();

pending.Id = 1;
pending.MyDate = DateTime.Now;
pending.MyString = someString;
pending.Save();
</code></pre>

This worked the first time I ran it, on an empty table, but not the second time when updating. I got a nullreference exception somewhere inside the subsonic repository. The solution was to add a primary key, as Rob suggested.

Just thought I'd mention it (thanks Rob).

I am testing subsonic 3, i can query my database but when i am inserting a record i have an exception. Here is my code:

Client lClient = new Client();
lClient.Name = "Peter";
lClient.FullName = "Richards";
lCliente.Save();

And i have a null reference exception on this generated code:

var newKey=_repo.Add(this,provider);

Any help is appreciated.

I am using ActiveRecords

Null Reference Excepion when saving data on subsonic 3

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

文章

问答

视频

教程

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云智能顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

聚焦“写作效率、视觉美观与运行性能”三方面进行全面升级，为您提供更高效、稳定的创作环境

社区富文本&Markdown编辑器全新改版上线，欢迎大家体验!

诚挚邀请您参与本次调研，分享您的真实使用感受与建议。您的反馈至关重要，感谢您的支持与参与！

社区新版编辑器体验调研

我正在测试亚音速3，我可以查询我的数据库，但当我插入一个记录时，我有一个异常。下面是我的代码：客户端lClient =新客户端()；lClient.Name = "Peter"；lClient.FullName = "Richards"；lCliente.Save()；并且我在这个生成的代码上有一个空引用异常：var ...

问在subsonic 3上保存数据时出现空引用异常
EN

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问在subsonic 3上保存数据时出现空引用异常EN