How to use Json Parser in CLR Procedure?

Question

I am getting CRAZY trying to use a Json Serializer/Deserializer in my Class Library and import my Assembly in SQL Server.

I am working with a WebAPI that response Json string , and I want to create CLR Sql Procedure that call that API and use the api result.

I tried 2 ways to Deserialize Json string :

1) System.Web.Script.Serialization

2) System.Runtime.Serialization.Json

First one get me this error :

Assembly 'system.web.extensions, version=4.0.0.0, culture=neutral, publickeytoken=31bf3856ad364e35.' was not found in the SQL catalog. (Microsoft SQL Server, Error: 6503)

And Second one :

Assembly 'system.runtime.serialization, version=4.0.0.0, culture=neutral, publickeytoken=b77a5c561934e089.' was not found in the SQL catalog. (Microsoft SQL Server, Error: 6503)

Are there any way to parse json in my class library ?! (Except of creating a Json Serializer/Deserializer for my self in class library !!!)

Visual Studio 2015 Community , Microsoft Sql Server 2016 Developer

Thank you in Advance.

Answer 1

Unfortunately there is no method that is both part of the .NET Framework (i.e. built-in) and SAFE.

If you want a built-in method, then you could try using the DataContractJsonSerializer class, which is in the System.Runtime.Serialization.Json namespace, which in turn is found in System.Runtime.Serialization.dll. You can find an example of using it here: How to: Serialize and Deserialize JSON Data. HOWEVER, in order to use this inside of SQL Server, you will need to import the System.Runtime.Serialization.dll since it is not one of the Supported .NET Framework Libraries. And because it is not supported, that means three things:

1. You need to set the database containing the Assemblies to TRUSTWORTHY ON (due to needing the PERMISSION_SET to be UNSAFE), something which is generally advised against due to it being a security risk.

2. You cannot be certain that the underlying code is not doing something that could cause "odd" behavior, such as caching values in static class variables. SQLCLR uses a single App Domain per each Assembly-owner + Database combination. Hence the class will be shared across all sessions that execute that code.

3. You cannot be guaranteed that System.Runtime.Serialization.dll (or either of its two dependent libraries: System.ServiceModel.Internals and SMDiagnostics) won't be changed into a mixed-mode DLL in a future .NET Framework update. Only pure MSIL libraries are allowed in SQL Server, so if any of those 3 ever change to instead be "mixed", then your code in SQL Server will start failing and there is no way to fix it; you will have to re-code it. And this has happened before: System.ServiceModel became mixed-mode with the release of .NET 4.0, and so code using it works in SQL Server 2005, 2008, and 2008 R2 (all linked to CLR v 2.0 and Framework versions 2.0 - 3.5), but won't work starting in SQL Server 2012 (all linked to CLR v 4.0 and Framework versions 4.0 and newer).

But, if you want to try it, do the following (it will auto-load the 2 dependent DLLs):

USE [someDB];

ALTER DATABASE CURRENT SET TRUSTWORTHY ON;

CREATE ASSEMBLY [System.Runtime.Serialization]
FROM 'C:\WINDOWS\Microsoft.NET\Framework64\v4.0.30319\System.Runtime.Serialization.dll'
WITH PERMISSION_SET = UNSAFE;

OR, you can include code to parse the JSON in your project. You have some options here as well:

1. While the "preferred" JSON parser is Json.NET, I have not been able to get it to load as a SAFE Assembly. It has been a few years since I have tried, but it had quite a few static class variables being used to cache values (helps performance, but won't work in a shared environment), and I seem to recall that it relied on some unsupported libraries (e.g. System.Runtime.Serialization).

2. I have used JsonFx with some success. That code also needed some updates to take care of static class variables, but it was possible. This project can handle converting from JSON to a few different markups.

3. As mentioned in @EvaldasBuinauskas's answer, you can try the LitJSON project. I have not tried this project so am not sure how well it works. It seems to be a bit smaller than the JsonFX project (doesn't do the other formats), but as of right now it has 25 outstanding issues while JsonFX only has 16.

   You should probably look at the list "Issues" for both projects to make sure that there isn't something reported that would cause an error for you.