Passing Output parameters to stored procedures using Dapper in C# code

Elucidating the approach

Juggling parameters with Dapper

DynamicParameters give you flexibility in managing input and output parameters dynamically. Use the Add method to specify parameters like DbType and direction. It's like performing a magic trick. DynamicParameters.Add() is your magical wand for effectively managing output parameters.

Adhering to naming conventions

Evade reserved names and prefixes like "SP_" as they might invite unnecessary conflicts or otherwise impact execution. Opt for unique and understandable names to ensure smooth operation.

The art of execution

Use CommandType.StoredProcedure as your go-to for executing stored procedures with Dapper, just like making coffee with your favorite coffeemaker.

Reflecting on Reflection

Reflection can have performance implications when adding parameters dynamically. To dodge such scenarios, employ DynamicParameters.AddDynamicParams() for adding anonymous objects.

Scooping out the output

Once the stored procedure has been executed, the output parameter's value is all set to be retrieved. It's like the cherry on top of your coding sundae.

Customizing extension methods

Consistent use of output parameters in transactions can benefit from custom extension methods. These act as bespoke tailoring service for your code, ensuring streamlined handling of SQL execution and parameter management.

Enhancing clarity with DbType

Defining DbType explicitly gives a better understanding of expected data types. For integers:

parameters.Add("@OutputParam", dbType: DbType.Int32, direction: ParameterDirection.Output); // Who let the Int out? Int, int, int, int!
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Streamlining method calls

Optimize your method calls when working with output parameters to make the code efficient and legible, just like a well-organized desk drawer.

Employing Anonymous objects for efficiency

Anonymous objects can swiftly add parameters while bypassing reflection, like a speedy mouse maneuvering its way through the maze:

dynamicParams.AddDynamicParams(new { InputValue = 123 }); // The magic of anonymity. Do we ever know who the real InputValue is?
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Going Pro: Advanced Scenarios

Handling multiple output parameters

In situations where your stored procedure returns multiple output parameters, confidently handle them all with DynamicParameters.

var p = new DynamicParameters();
p.Add("@FirstOutput", dbType: DbType.Int32, direction: ParameterDirection.Output);
p.Add("@SecondOutput", dbType: DbType.Decimal, direction: ParameterDirection.Output); // To be or not to be, that's the output question!
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Profiting from Post-execution insights

Information gathered after the execution can offer insights into the performance of the procedure and spot unusual behavior. It's like detective Conan solving a case.

int id = p.Get<int>("@FirstOutput");
decimal price = p.Get<decimal>("@SecondOutput");
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Dealing with nulls for output parameters

Skillful handling of null values for output parameters can be achieved using nullable types or implementing a check before retrieval:

int? possibleNullResult = p.Get<int?>("@NullableOutput"); // The invisible man of data points - NULL!
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Transactional execution

To execute your procedure within a transaction, pass the transaction object to the Execute call. It's all about keeping your ducks in a row.

using (var transaction = connection.BeginTransaction())
{
    connection.Execute("sp_YourProcedure", p, transaction, commandType: CommandType.StoredProcedure); // Let's get this transaction rolling!
}
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