Xamarin.Android上的JsonSerializationException'无法找到构造函数' [英] JsonSerializationException 'Unable to find a constructor' on Xamarin.Android

问题描述

我的代码有一个非常奇怪的问题，考虑到我半年前还没有，这是一个相当新的问题.长话短说，我已经在Xamarin上制作了一个应用程序，并在大约半年前在所有3家商店(App Store，Google Play和Microsoft Store)上发布了该应用程序.

I have this very odd problem with my code, and it's a pretty new problem, considering I didn't have it half a year ago. Long story short, I've made an app in Xamarin, and released it about half a year ago, on all 3 stores (App Store, Google Play and Microsoft Store).

昨天，一个用户报告了Android应用程序的问题，在我修复并重新编译该问题之后，我现在遇到了Json.NET的新错误

Yesterday a user reported a problem with the Android app, and after I got that fixed and recompiled, I'm now encountering a new error with Json.NET

例外是

Newtonsoft.Json.JsonSerializationException: Unable to find a constructor to use for type Rowlog.Common.Dtos.CompressedTripData. A class should either have a default constructor, one constructor with arguments or a constructor marked with the JsonConstructor attribute. Path 'tripCoordinates', line 1, position 19.

在您问之前，是的，Rowlog.Common.Dtos.CompressedTripData确实具有无参数构造函数(嗯，它根本没有一个，我们都知道是同一件事).

And before you ask, yes Rowlog.Common.Dtos.CompressedTripData does indeed have a parameterless constructor (Well, it doesn't have one at all, which we all know is the same thing).

就像我说的，这是当我从Android设备上的服务器加载CompressedTripData对象时.在iOS和Windows Phone上加载完全相同的对象可以顺利进行. 我猜想这是Json.NET或Xamarin.Android中的最新变化，这是导致此问题的原因(其他应用大约半年前仍在使用Json.NET库.不确定是否已经使用了Json.NET库).此后的任何更新)

And like I said, this is when I load a CompressedTripData object from the server on an Android device. Loading the exact same object on iOS and Windows Phone works without a hitch. I'm guessing it's gotta be a recent change in either Json.NET, or Xamarin.Android which is causing this (The other apps are still using the Json.NET libraries from about half a year ago. Not sure if there has even been any updates to it since)

还有其他人遇到过类似的问题吗?如果是，您如何解决呢?

Has anyone else encountered a similar problem, and if so, how have you fixed it?

推荐答案

在项目属性的"Android选项"标签中，有一个链接器"标签. 是链接"下拉列表中的仅Sdk程序集"中选定的选项，还是"SDK和用户程序集"?

In the 'Android options' tab of the project properties, there is a 'linker' tab. Is the selected option in the 'Linking' dropdown "Sdk Assemblies only" or is it "Sdk and user assemblies"?

如果是后者，则在链接时将跳过无参数构造函数，因为未检测到任何用法.因此，将其更改为仅限于SDK程序集".

If it is the latter, the parameterless constructor is skipped when linking, because no use is detected. So change it to "Sdk Assemblies only".

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