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Class DbCommandSourceGenerator ​

Namespace: Momentum.Extensions.SourceGenerators.DbCommand
Assembly: Momentum.Extensions.SourceGenerators.dll

Source generator that creates database command handlers and parameter providers for types marked with DbCommandAttribute.

csharp
public class DbCommandSourceGenerator : IIncrementalGenerator

Inheritance ​

object ← DbCommandSourceGenerator

Implements ​

IIncrementalGenerator

Inherited Members ​

object.GetType(), object.MemberwiseClone(), object.ToString(), object.Equals(object?), object.Equals(object?, object?), object.ReferenceEquals(object?, object?), object.GetHashCode()

Remarks ​

DbCommand Source Generator ​

Generator Capabilities ​

This generator provides the following capabilities:

  • Parameter Mapping: Generates ToDbParams() extension methods for parameter mapping
  • Command Handlers: Creates Wolverine command handlers for database operations
  • Multiple Command Types: Supports stored procedures, SQL queries, and functions
  • Parameter Case Conversion: Handles parameter case conversion (None, SnakeCase)
  • Custom Parameter Names: Respects Column attributes for custom parameter names

The default parameter case can be configured via MSBuild property: DbCommandDefaultParamCase

Generated Code Structure ​

Parameter Extensions ​

For each type marked with [DbCommand], the generator creates extension methods:

csharp
public static class {TypeName}DbExtensions
{
    public static void ToDbParams(this {TypeName} source, DbParameterCollection parameters)
    {
        // Generated parameter mapping code
    }
}

Command Handlers ​

When Sp, Sql, or Fn properties are specified, the generator creates Wolverine handlers:

csharp
public class {TypeName}Handler
{
    public async Task<{ReturnType}> Handle({TypeName} command, [FromServices] IDbConnection connection)
    {
        // Generated database execution code
    }
}

Configuration Options ​

MSBuild Properties ​

Configure the generator behavior via MSBuild properties:

  • DbCommandDefaultParamCase: Sets default parameter case conversion (None, SnakeCase)
  • DbCommandParamPrefix: Adds a prefix to all generated parameter names

Attribute Configuration ​

Control generation per type using the DbCommandAttribute:

csharp
[DbCommand(
    Sp = "sp_create_user",           // Stored procedure name
    Sql = "INSERT INTO users...",    // Direct SQL query
    Fn = "fn_calculate_total",       // Function name
    ParamCase = DbParamsCase.SnakeCase // Parameter case override
)]
public record CreateUserCommand(string Name, string Email);

Code Generation Process ​

1. Type Discovery ​

The generator uses incremental source generation to discover types:

csharp
var commandTypes = context.SyntaxProvider
    .ForAttributeWithMetadataName(
        fullyQualifiedMetadataName: "Momentum.Extensions.Abstractions.Dapper.DbCommandAttribute",
        predicate: static (_, _) => true,
        transform: static (ctx, _) => ctx.TargetSymbol as INamedTypeSymbol);

2. Settings Resolution ​

MSBuild properties are resolved and combined with attribute settings:

csharp
var dbCommandSettings = GetDbCommandSettingsFromMsBuild(optionsProvider);
var typeInfo = new DbCommandTypeInfoSourceGen(namedTypeSymbol, dbCommandSettings);

3. Code Generation ​

Two separate generators run for each type:

  • DbExtensions: Always generated for parameter mapping
  • Handler: Only generated when database operation is specified

Error Handling ​

The generator includes comprehensive error handling:

  • Diagnostic Reporting: Reports compilation errors for invalid configurations
  • Early Exit: Stops generation if errors are detected
  • Type Validation: Ensures types are properly configured before generation

Performance Considerations ​

  • Incremental Generation: Only regenerates when source files change
  • Selective Generation: Handlers only generated when needed
  • Compilation Optimization: Uses efficient Roslyn APIs for type analysis

Constructors ​

DbCommandSourceGenerator() ​

csharp
public DbCommandSourceGenerator()

Methods ​

Initialize(IncrementalGeneratorInitializationContext) ​

Initializes the incremental generator.

csharp
public void Initialize(IncrementalGeneratorInitializationContext context)

Parameters ​

context IncrementalGeneratorInitializationContext

The generator initialization context.

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