Dapper error handling Mar 6, 2025 · This is Part 10 of a series on using Dapper to simplify data access with ADO. Base. SqlMapper. NET Core web API + Dapper – Asynchronicity → Apr 23, 2021 · Exception: System. 0 (ASP. Mar 29, 2024 · Explore best practices for unit testing Dapper applications in . Apr 26, 2021 · Dapper is an example of Micro ORM, in fact, it is called the King of Micro ORM because of its speed and ease of work. Dapper allows you to execute non-query commands that are not intended to return resultsets, such as INSERT, UPDATE, and DELETE statements. First, we create a connection to the database using a SqlConnection object and then create an SQL query to select the data from the database and pass it to the ExecuteReader method of Dapper. The QueryAsync failed without any retries and modifying the AuthorizedSqlCondition didn’t seem change the way different SQL statement failures were handled. Use using statements to ensure proper cleanup even when exceptions occur. Jan 14, 2020 · I have a stored procedure which I can't modify and I'm trying to get the PRINT message that get's returned if an error occurs. GiiC. The other is a parameter object that can be an Nov 5, 2020 · I am using Dapper and want to return Today's Sales amount using a Stored Procedure but if there is no sale for today, it returns empty values which in turn throws an exception "'Object referen May 4, 2024 · Dapper is a lightweight, high-performance data access tool built by the Stack Overflow team. Read, Dapper throws a "No columns were selected" exception. " Apr 25, 2024 · I would expect an exception to be thrown due to the SQL error in the script, which occurs after attempting to assign an incorrect datatype: SET @intvar = 'A'. ThrowDataException (Exception ex, Int32 index, IDataReader rea Mar 1, 2017 · at Dapper. are not related to an issue with Dapper but rather a bad usage of the connection. 1 I'm having an issue with Execute and ExecuteAsync method. Settings. Now, let's test one method. Dapper ExecuteReader The following example shows how to use the ExecuteReader method. TaskAwaiter. When I have some records everything works as expected. Here is the code: public IEnumerable&l Mar 27, 2016 · Dapper throws exception second time you run a query if different results schema #488 Jul 23, 2024 · Introduction Dapper is a simple, lightweight Object-Relational Mapping (ORM) library for . Overview When executing a query Dec 9, 2019 · Take advantage of the async methods in Dapper to improve the scalability and performance of your ASP. Oct 30, 2023 · Using Dapper series (5 Part Series) 1 Using Dapper - C# Part 1 2 Using Dapper - C# Part 1-A 3 Import data from a database with Dapper and SpreadsheetLight to Excel in C# 4 Dapper DateOnly/TimeOnly 5 Dapper Stored Procedure tip Jul 25, 2018 · How to get user defined SQLException number with Dapper Asked 7 years, 2 months ago Modified 7 years, 2 months ago Viewed 2k times Jan 6, 2015 · It would be great if there was a simple additional optional parameters on the Query and Execute methods for retrying a query automatically to handle transient errors. It is designed to work with various databases, including SQL Server, Oracle, MySQL, and PostgreSQL. Feb 22, 2023 · Dapper is an open-source ORM tool that is easy to use and lightweight, which makes it a popular choice for . It is designed to provide high performance and reduce the overhead typically associated with traditional ORMs. Mar 1, 2017 · Dapper should be throwing a SqlException when used against a SqlConnection. The connection's current state is connecting. NET. NetView on GitHub Dapper - a simple object mapper for . Mar 23, 2023 · How to build a . ThrowForNonSuccess(Task Jun 11, 2024 · After investigating the Dapper source code I think we may have some exception that is being hidden by Dapper. Dapper, Visual Studio 2019, and . There was limited documentation about how to use ADO The: object o = null; string s = (string)o; does not throw an exception, so I'm wondering if the exception was really because of ExecuteScalar() returning a null? @HemantKothiyal did you actually test this in run-time and confirmed that replacing a cast with as stops the exception? And did you get the expected result in getusername? Sep 6, 2023 · Hi all Friends, I am returning rows from a Sqlite/Dapper transaction. 35 . Oct 20, 2023 · Dapper Query SingleOrDefault Discover How to Return a Single Row or Default Value Description Dapper's QuerySingleOrDefault method is used to execute a query and return the first row of the results, or the default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence. Jan 30, 2020 · i am using Dapper for accessing sqlite database and getting 'String was not recognized as a valid DateTime. Apply these concepts to build efficient, secure data access layers. NullReferenceException: Object reference not set to an instance of an object. NET Simpler . g. Contrib. Sep 4, 2020 · Hello. I know that dapper is opening connection itself if it is closed so this works ideally in 99% Exception "Invalid operation. NET Core applications. The Execute method takes a few different parameters: One is the command text (the SQL query) to execute. Dec 4, 2024 · In this article, we’ll explore advanced solutions to common Dapper issues, leveraging modern software engineering principles such as SOLID, Design Patterns, memory optimization, caching Use Try-catch block in each action methods or implement Global exception handling through custom middleware to avoid code repetition in each action method. Our stack trace reveals an exception being thrown in OnAfterGridAsync which is being called in a finally block. Exception exception, DevExpress. We'll be handling exceptions with the use of a few different Polly policies. The code in my stored procedure is. Discover best practices for high-performance data access. But what if we are using dapper? How can we trace the SQL and get query execution times? We already have our Seriog outputting to SQL Server and our middleware from the last post. In this case, we're looking for SqlExceptions, Timeouts, and a wrapped Win32 exception. Logging, ORM, SQL, sqlazure, SQLException, SQLServer, Web API, WebAPI. net. Jul 8, 2016 · I have a lot a row with null in this column, and when the first line with 0 comes, Dapper throw the same Exception. I understand that this block is necessary. Common. Dumb outcome and considered deleting, but maybe leaving it here in case anyone else experiences the same issue could be helpful? Mar 14, 2024 · Learn how to manage database connections and implement efficient pooling strategies using Dapper in . This reduces round trips to the database and allows efficient handling of related data sets. This article explores the integration Feb 11, 2019 · Asp Net Core SQL Custom Configuration Provider with Dapper and Error Handling Asked 6 years, 9 months ago Modified 6 years, 9 months ago Viewed 2k times Feb 14, 2022 · Dapper is a lightweight framework for data access. HandleException [ow. It provides a minimalist approach to data access layer in . The difference between Query and Query<T> is Jan 31, 2024 · Let's learn how to use Dapper in ASP. Rolling back to 2. In addition, you can use Dapper Plus to BulkInsert data in your database. Post navigation ← . '. Contrib is an open-source library that provides a set of extension methods to Dapper, which can help you to perform CRUD (Create, Read, Update, Delete) operations more efficiently. I put 0 in every row, and there is no exception. NET Core. In this guide, we will explore how to use stored procedures in C# with Dapper. NET library for data access and object-relational mapping (ORM) that supports . NET applications, focusing on raw Aug 29, 2021 · Make all your Dapper Queries resilient with retries using Polly. CommandTimeout = 0; You can initialize this static property on the application load or in the database class constructor. Dapper. NET core 3. ThrowDataException(Exception ex, Int32 index, IDataReader reader, Object value) in /_/Dapper/SqlMapper. Extensions. I'd like to do something more globally that would include any parameters in the exception if, say, a stored proc threw a SqlException. In this blog, we’ll demystify why this exception happens, compare . GridReader. ThrowDataException(Exception ex, Int32 index, IDataReader reader, Object value) at Deserialized6d8a313-98ee-4df1-b734-3ffe3df435f2(IDataReader ) Jul 7, 2022 · Check out our courses: https://bit. Learn how to use a transaction when saving data and completing it with 'Commit' or 'Rollback'. at Microsoft. Mar 2, 2018 · Is it possible the get original SQL error message by using dapper? I would like to tell my case with using an example. Its intuitive methods, such as Query, QueryFirst, Execute, and QueryMultiple, allow developers to write clean, efficient, and performant database interactions with minimal overhead. 0 applications Run the CRUD example API locally Test the API with Postman Connect an Angular app with the . . Yes, the conn Aug 14, 2015 · As soon as I do the query. Mar 22, 2014 · dapper sql in-clause throws exception Asked 11 years, 8 months ago Modified 3 years, 10 months ago Viewed 4k times Feb 21, 2023 · Dapper. cs:line 157 at Dapper. Net Core 3. Jun 16, 2025 · Unlock the power of Dapper by understanding the basics and more advanced topics. Feb 10, 2023 · Tutorial built with . Dapper is fast and efficient because it does not add any overhead to the data access layer and is very easy to start. E. (connection string will be injected through dependency) public User Add(User user) { string Sep 7, 2020 · Summary Large-scale, complex projects benefit the most from readability improvments, and when using Dapper and C# the Dapper Base Repository pattern allows for better code readability and a single point of failure by creating a base class with generic methods that allow for querying and execution against a SQL database. Mvvm. StoredProcedure); var re Jul 25, 2018 · How to get user defined SQLException number with Dapper Asked 7 years, 2 months ago Modified 7 years, 2 months ago Viewed 2k times The Dapper Execute method allows you to insert single data or insert multiple rows. Jan 18, 2018 · In my last post we touched on what we get from EF Core in our Serilog log entries. Please could I get some feedback? May 6, 2023 · The splitOn parameter tells Dapper which columns to split on. Oct 30, 2023 · Using Dapper series (5 Part Series) 1 Using Dapper - C# Part 1 2 Using Dapper - C# Part 1-A 3 Import data from a database with Dapper and SpreadsheetLight to Excel in C# 4 Dapper DateOnly/TimeOnly 5 Dapper Stored Procedure tip Nov 26, 2024 · I am getting this exception from Dapper. The connection is closed. Is that the correct behaviour. NET Data Access With Dapper - Part 1 Dapper Part 2 - Querying The Database Dapper Part 3 - Executing Queries Dapper Part 4 - Passing Data To And From The Database Dapper Part 5 - Passing Data In Bulk To The Database Dapper Part 6 - Returning Multiple Sets Apr 19, 2025 · Multiple Result Sets (GridReader) Relevant source files The GridReader provides capabilities for processing multiple result sets from a single database query in Dapper. We a Aug 25, 2025 · Unlock the power of Dapper by using Transaction. NET 7. Jun 16, 2025 · Unlock the power of Dapper by using Stored Procedure. [Table("Product")] public class ProductItem { public decimal ProductID Feb 24, 2023 · Learn how to use the Dapper framework to execute a stored procedure in a C# application. The information returned to a caller was generic and the only useful information was the “traceId”. Prerequisites Before Scenarios that throw the exception The connection had been disposed. Tutorial contents Example API overview Tools required to develop . net-6. If you only need to change this mapping logic you can do that using To select data from a table or view using Dapper, you need to create an instance of the IDbConnection interface. Learn about isolating DB logic, dependency injection, mocking frameworks, and more. cs:line 442\r\n--- End of stack trace from previous location where exception was thrown ---\r\n at System. Jul 17, 2015 · When I've come to use this, I want to know if it fails or not by catching an exception (s) and not just a general Exception. SqlMapper' threw an exception" is being thrown only on certain PCs when using 2. NET applications, focusing on raw Aug 30, 2024 · How to handle Dapper's timeout issue while using a long running StoredProc on Asp. NET and SQL date/time types. NET Core Web API by using different querys, executions, transactions and repository pattern. 78. All Dapper querying methods allow executing stored procedures without writing extra code by specifying the commandType parameter to 'StoredProcedure'. NET Overview A brief guide is available on github Questions on Stack Overflow should be tagged dapper Installation From NuGet: Dec 31, 2024 · Using Dapper with Entity Framework Core In the realm of . Dapper is a simple and efficient . GetTypeDeserializerImpl. NET Data Access With Dapper - Part 1 Dapper Part 2 - Querying The Database Dapper Part 3 - Executing Queries Dapper Part 4 - Passing Data To And From The Database Dapper Part 5 - Passing Data In Bulk To The Database Dapper Part 6 - Returning Multiple Sets Mar 25, 2022 · Ignoring the exception popup and clicking 'Continue' allowed my code to move on to the catch block. Sep 3, 2019 · When an exception is raised in the called code, Polly will look to see if it's an exception we want handled. I was expecting an empty collection or at the least a n I am updating a quantity in my cart, but it is throwing a Sequence has no elements' exception. cs:line 3948 at Deserialize68929759-6271-4665-a68e-ff25a40601eb(DbDataReader) at Dapper. 0, Dapper 2. NextResultAsync () in /_/Dapper/SqlMapper. Jul 21, 2015 · In my opinion, your code is fine and Dapper will open and close the collection itself but the exception that you get is because the connection pool has no free connection to return at the timeout time. The stored procedure which executing in the code returns just 200 rows within no time. Net. GridReader multiResult = new DapperRepository(). ViewModels. NET developers. NET API Connect a React app with the Dec 17, 2024 · Overall, Dapper is a powerful and lightweight micro-ORM that simplifies data access in . Plus BulkInsert exception Invalid Object when Object exist . 0 and SQLite In this tutorial we'll show how to build a . NET `DateTime` to SQL `DateTime2` using Dapper. Feb 1, 2011 · Dapper - a simple object mapper for . What can cause them and how to solve them? Feb 11, 2019 · Asp Net Core SQL Custom Configuration Provider with Dapper and Error Handling Asked 6 years, 9 months ago Modified 6 years, 9 months ago Viewed 2k times Feb 14, 2022 · Dapper is a lightweight framework for data access. NET and SQL date/time types, and provide a step-by-step guide to resolve it by mapping . NET Core and C# language. NET applications. Jan 24, 2025 · This lesson has explored Dapper’s execution pipeline, from connection management to error handling. Jun 6, 2021 · We want our solution to to extend all the built-in functionality of Dapper and add layer of resiliency that manages transient database errors and other error types. Runtime. Any help is appreciated. And I don't know what that even means. Jan 24, 2025 · When working with transactions in Dapper, always verify connection state management and properly handle transaction disposal. The solution to fix this issue is easy: just ensure that your production environment also contains the license name and the license key. Learn how to use stored procedure with input and output parameters for your CRUD operations. I tried to open connection myself and close myself. Enhance your data access layer with proven techniques and reliable strategies. Net Core, C#, Dapper, Exception, logging, Microsoft. (connection string will be injected through dependency) public User Add(User user) { string Dapper - a simple object mapper for . It however populates the first record of the result with the error message. Instead, the selected value is returned without any errors or exceptions. I am using dapper. Sep 7, 2020 · Summary Large-scale, complex projects benefit the most from readability improvments, and when using Dapper and C# the Dapper Base Repository pattern allows for better code readability and a single point of failure by creating a base class with generic methods that allow for querying and execution against a SQL database. Please share your ideas on how to use transact Mar 4, 2025 · This is Part 8 of a series on using Dapper to simplify data access with ADO. The method is called but it never returns a result, and the query is not executed. As you already learned in previous posts, with simple object you don’t have to do anything special since Dapper automatically maps database columns to properties with the same name. Sep 13, 2021 · I am trying out Dapper and I have stumbled upon this exception: System. Dec 7, 2016 · I tried to Execute async and not asnc. This approach makes interacting with a database both performant and easy, as you can Dapper does not catch error when I try and insert a duplicate record. NET Core) API with Dapper and SQLite that supports CRUD operations. To do this, you use the Execute extension method of the IDbConnection interface, which Dapper implements. ADP. Apr 15, 2024 · at Dapper. Jul 11, 2018 · System. Sep 6, 2023 · Hi all Friends, I am returning rows from a Sqlite/Dapper transaction. Aug 10, 2023 · Dapper. I don't see any way to handle transactions with dapper. HandleException (System. While it works fine on short-running storedprocs, one of the storedproc takes an extended time to complete and I get the timeout error. patreon. Data. Aug 29, 2021 · Make all your Dapper Queries resilient with retries using Polly. Bookmark the permalink. Dapper works in the following way - First, it creates an IDbConnection object and allows us to write queries to perform CRUD operations on the database. \r\n at Dapper. You can easily reproduce all those errors without Dapper. Nov 14, 2024 · When trying to query a row with a Date column using dapper i get Object must implement IConvertible but it works fine with ADO. 100+ Options Add Flexibility to Your Data Saving Operations Being able to save your entities quickly is crucial, but having the flexibility to save them THE WAY YOU WANT often holds greater importance, especially when using Bulk Extensions Methods and Single Extensions Methods. Jun 8, 2022 · So I could revisit my approach I added a controller with two methods one which returns an HTTP 500 error and another which has un-caught exception. 14 hours ago · While Dapper simplifies data access, its default type mappings don’t always account for the differences between . Prerequisites Before getting started, you must have Dapper supports mapping all kinds of relationships using the SplitOn parameter to map your One-To-Many, One-To-One, or Many-to-Many relation. Dapper Query The primary methods used for selecting data are Query and Query<T> and their async counterparts. For SqlExceptions and Win32 exceptions, we're going to further look to see if we can retry it with a call to SqlServerTransientExceptionDetector. Jun 14, 2021 · This entry was posted in . QueryAsync[T](IDbConnection cnn, Type effectiveType, CommandDefinition command) Jul 28, 2016 · Run into a small issue with dapper trying to map the previous column to the wrong field in the class and as such is throwing "Specified cast is not valid". 0 dapper-plus 1,449 asked Aug 10, 2023 at 23:58 Jul 15, 2016 · The lack of response on this issue is rather unsettling. NET development. Learn how to use methods such as 'ExecuteAsync' and 'QueryAsync' in your async methods. " sometimes it says " The connection was not closed. Before we learn into all the available options, let's first understand how to use them with the UseBulkOptions method Mar 23, 2023 · How to build a . Net Core project and I had an unexpected result while testing some functionalities, so I decided to ask about how the asynchronous Apr 21, 2020 · When writing a unit test using XUnit, Dapper, Moq. Net Core I will investigate what is happening - I strongly suspect that it is the CommandBehavior. Dapper Version 2. ExceptionWithStackTrace (Exception e) --- End of stack trace from previous location --- at Dapper. Customer objCustomer = null; using (SqlMapper. Net Full exception: Mar 17, 2017 · Can anyone please suggest how to check if there are any records in the resultset using Dapper ORM. You could try changing the splitOn parameter to "CustomerId,ProductId,FirstName,StockQuantity" to include the ProductId column to see if that helps. SqlMapper Nov 7, 2019 · When we execute below code, we are getting below exception from Dapper. May 10, 2020 · To map - or better - deserialize data coming from your database into a complex custom object Dapper supports a feature named "Custom Handlers". Then you can use the Query<T> or QueryAsync<T> method to execute the SELECT query and store the results in a list of objects. Feb 20, 2024 · Exception handling is a critical aspect of software development, ensuring robust and error-free applications. I will investigate what is happening - I strongly suspect that it is the CommandBehavior. At first I thought that maybe there was a null value being pas Jun 6, 2021 · Background Dapper is a lightweight ORM for use in high performance database transactions that uses hand written SQL scripts and transforms the results into objects. Camilo Reyes explains how to query, call stored procedures, and more with Dapper in C#. Mar 10, 2025 · This is Part 13 of a series on using Dapper to simplify data access with ADO. NET Core web API + Dapper – Less is more . ly/cdmz-courses Support us on Patreon and get the source code: https://www. InvalidOperationException: The ConnectionString property has not been initialized. Mar 29, 2021 · The error "The type initializer for 'Dapper. 0 CRUD API with Dapper and a PostgreSQL database. For information about handling multiple result sets asynchronously, see also Asynchronous Operations. Jun 16, 2025 · Unlock the power of Dapper by using Async Methods. I'm trying to use the multimapping feature of Dapper to return a list of ProductItems and associated Customers. And if I run into an exception instead of the application crashing, I would like to return an empty row. Unfortunately, we don’t get any logging out of the box for dapper like we do with EF Core - so, we need to do a bit of work. May 4, 2024 · Dapper is a lightweight, high-performance data access tool built by the Stack Overflow team. We Apr 12, 2019 · [ow. Which (if any) exceptions are thrown? Aug 30, 2024 · I am using Dapper for my data access. MoveNext() in C:\\projects\\dapper\\Dapper\\SqlMapper. NET Data Access With Dapper - Part 1 Dapper Part 2 - Querying The Database Dapper Part 3 - Executing Queries Dapper Part 4 - Passing Data To And From The Database Dapper Part 5 - Passing Data In Bulk To The Database Dapper Part 6 - Returning Multiple Sets The Dapper QueryMultiple method allows you to select multiple results from a database in a single query and then, after reading those results, map them. Dapper Cast Exception on NULL value in column Asked 7 years, 10 months ago Modified 6 years, 9 months ago Viewed 6k times Apr 6, 2018 · Query and QueryMultiple throws null reference exception when my table doesn't have any records. com/CodeMazeIn this video, we are Jun 14, 2021 · I then added an OpenAsync just before the Dapper query so I could open the database connection, pause the program with a breakpoint, unplug the LAN cable and then continue execution. 0, I'm trying to mock a call that will throw an exception using the code below which compiles correctly Jul 2, 2023 · Exception handling in C# can significantly benefit from improved code readability and maintainability. IMessageBoxService messageBoxService) from what it seem ,when sql buffer is unable to parse value, it thows an out of memory exception - this exception breaks all application. We use Dapper heavily in some high value products and yet we don't seem to be receiving any support for a genuine issue. WaitAndRetry - I use this everywhere now. SingleResult hint (that dapper uses in QueryFirstOrDefault) preventing errors after the first grid being observed. 42) with the AdoMdConnection against an Analysis Services (tabular) data source, and my dataset has nulls in it, and I've got the wrong type on my model (I used decimal?, should Dapper supports transactions and allows you to commit/rollback the current transaction. ViewModel. NET, Dapper, SQL Azure and tagged . Net Core, ASP. Here is my User Repository Add method. Jul 10, 2025 · Learn common issues within Dapper. QueryMultipleAsync(query, parameters, commandType: CommandType. at Dapper. net core and Dapper in our App. NET Core, Microsoft… Apr 12, 2025 · Explore tips and best practices for managing transactions with Dapper in . Jun 16, 2025 · However, your production environment doesn't have those values, so it goes into trial mode and raises the trial exception at the end of the month. CompilerServices. One of the powerful features of Dapper is its support for executing stored procedures. Async. 35 and rebuilding and it works on these PCs as expected. Contribute to DapperLib/Dapper development by creating an account on GitHub. GridReader when calling var resultSet = await SqlConnection. d__33 1. For Example; Let's say we have store procure and the procedure contains this couple line of SQL code BEGIN TRY -- Gene Feb 27, 2017 · I am considering using Dapper and was wondering about exception handling. 0. Apr 17, 2018 · I'm using Dapper Repositories to access to the Data Base in my ASP. This helps in removing duplication, and in case you decide to change it later, you change it once in one place. Learn more about how to use transactions, transactions scopes, and more. May 8, 2019 · I would like to run multiple insert statements on multiple tables. InvalidOperationException: Invalid attempt to call NextResultAsync when reader is closed. Why not execute the the query then apply the select if there not an exception? Mar 11, 2016 · If I use Dapper (v1. Mar 25, 2022 · Ignoring the exception popup and clicking 'Continue' allowed my code to move on to the catch block. NET application development, efficient data access is a cornerstone of performance and scalability. In . Learn what Dapper is, how it works, and all the documentation you need to get started. Thanks ! Jan 7, 2017 · I am using Asp. kpzxvk vjc rvcfsj kwpue ihuzyu epunw tihbxp mnph fvxb inmdxk fqoajx gagtqt wtbu sbhwi smbfgcx