How I Solved the Npgsql PostgreSQL Error the CLR type isn't natively supported by Npgsql or your PostgreSQL

As a .NET developer, I recently encountered a challenging issue related to Npgsql and PostgreSQL. In this blog post, I will share the error I faced and the solutions I implemented to resolve it. I'll walk you through the problem and the step-by-step solutions I applied to fix it. This article has a step-by-step guide on how I Solved the Npgsql PostgreSQL Error the CLR type isn't natively supported by Npgsql or your PostgreSQL.

The Error:

The specific error message I encountered was:

"The CLR type <assembly name> isn't natively supported by Npgsql or your PostgreSQL. To use it with a PostgreSQL composite, you need to specify DataTypeName or to map it, please refer to the documentation."

This error indicated a compatibility issue between Npgsql and PostgreSQL when dealing with a particular CLR type. To address this, I had to explore distinct solutions:

Steps 1: PostgreSQL Procedure

In my first approach, I decided to create a PostgreSQL stored procedure to handle the data. Here's the code for the PostgreSQL procedure:

1. CREATE OR REPLACE FUNCTION public.getCustomerDetails(  
2. p_requestdata varchar DEFAULT NULL::varchar)  
3.  RETURNS TABLE(result character varying, message character varying)  
4.  LANGUAGE plpgsql  
5. AS $function$  
6. DECLARE  
7. v_companyName varchar(8000);  
8. BEGIN  
9.     SELECT Name   
10.     FROM jsonb_populate_record(NULL::public.typeCompanyDetails, p_requestData);  
11.   
12.     -- My logic here  
13.   
14.     RETURN QUERY  
15.     SELECT  
16.         CASE WHEN v_rowCount > 0 THEN 'SUCCESS' ELSE 'FAILED' END::character varying AS status,  
17.         (SELECT TextInEnglish FROM app.tblAdminTemplateMaster   
18.         WHERE Purpose = 'RequestRaisedFailed')   
19.     END::character varying AS message;  
20. END;  
21. $function$  
22. ;  

Step 2: C# Dapper

In the second part of my solution, I had to modify my C# code to work with the PostgreSQL procedure. I used Dapper, a micro ORM, to execute the stored procedure. Here's the relevant C# code

1. public async Task GetRecords(MyCustomClass[] requestData)  
2. {  
3.     var procedure = _configuration["Procedure:getrequestdata"];  
4.     var parameters = new DynamicParameters();  
5.       
6.     // Old implementation  
7.     // parameters.Add("@p_requestdata", requestData);  
8.       
9.     // New implementation  
10.     parameters.Add("@p_requestdata", JsonConvert.SerializeObject(requestData), DbType.String);  
11.       
12.     using IDbConnection dbConnection = new NpgsqlConnection(_connectionString);  
13.     dbConnection.Open();  
14.       
15.     return await dbConnection.QueryFirstOrDefaultAsync<T>("SELECT * FROM " + procedure, dynamicParameters);  
16. }  

In this C# code, I modified the way I passed the requestData to the PostgreSQL procedure. Instead of passing it directly, I serialized it to a JSON string, ensuring compatibility with the PostgreSQL procedure.

Conclusion:

By combining the PostgreSQL stored procedure and the adjusted C# code, I successfully resolved the compatibility issue between Npgsql and PostgreSQL for this specific CLR type. It's essential to keep in mind that database errors can often be resolved through a combination of server-side and client-side adjustments, as demonstrated in this solution.