I'm trying to create a StagingTableProvider which can take a source and automatically create staging tables.
Here is a suggestion for a change which would make this more flexible:
Interface Flexibility for Custom Transformations
Enhanced Interface Design
public interface ISameAsSourceProvider
{
bool SupportsSameAsSource { get; }
// This method gives you complete control over destination schema creation
Schema CreateDestinationSchemaFromSource(Schema sourceSchema, string? requestedDestinationTableName = null);
// Optional: Transform individual table names
string TransformTableName(string sourceTableName) => sourceTableName;
// Optional: Transform column definitions
Column TransformColumn(Column sourceColumn) => sourceColumn;
}
Implementation Examples
Example 1: Change Table Names
public class StagingTableProvider : BaseProvider, IDestination, ISameAsSourceProvider
{
public bool SupportsSameAsSource => true;
public Schema CreateDestinationSchemaFromSource(Schema sourceSchema, string? requestedDestinationTableName = null)
{
var destinationSchema = new Schema();
foreach (var sourceTable in sourceSchema.GetTables())
{
// Transform table name with prefix
var destinationTableName = $"Staging_{sourceTable.Name}";
var destinationTable = destinationSchema.AddNewTable(destinationTableName, sourceTable.SqlSchema);
// Copy and potentially transform columns
foreach (var sourceColumn in sourceTable.Columns)
{
var transformedColumn = TransformColumn(sourceColumn);
destinationTable.AddNewColumn(transformedColumn.Name, transformedColumn.Type, transformedColumn.IsPrimaryKey, transformedColumn.IsAutoIncrement);
}
}
return destinationSchema;
}
public string TransformTableName(string sourceTableName)
{
return $"Staging_{sourceTableName}";
}
public Column TransformColumn(Column sourceColumn)
{
// Example: Add audit columns
var column = sourceColumn.Clone();
// Could modify column types, names, constraints, etc.
if (sourceColumn.Name == "CreatedDate")
{
column.Name = "StagingCreatedDate";
}
return column;
}
}
Example 2: Add Staging-Specific Columns
public Schema CreateDestinationSchemaFromSource(Schema sourceSchema, string? requestedDestinationTableName = null)
{
var destinationSchema = new Schema();
foreach (var sourceTable in sourceSchema.GetTables())
{
var destinationTable = destinationSchema.AddNewTable(sourceTable.Name, sourceTable.SqlSchema);
// Copy all source columns
foreach (var sourceColumn in sourceTable.Columns)
{
destinationTable.AddNewColumn(sourceColumn.Name, sourceColumn.Type, sourceColumn.IsPrimaryKey, sourceColumn.IsAutoIncrement);
}
// Add staging-specific audit columns
destinationTable.AddNewColumn("StagingLoadDate", typeof(DateTime), false, false);
destinationTable.AddNewColumn("StagingBatchId", typeof(string), false, false);
destinationTable.AddNewColumn("StagingSourceFile", typeof(string), false, false);
destinationTable.AddNewColumn("StagingProcessedFlag", typeof(bool), false, false);
}
return destinationSchema;
}
Example 3: Data Type Transformations
public Column TransformColumn(Column sourceColumn)
{
var column = sourceColumn.Clone();
// Example transformations for staging scenarios
switch (sourceColumn.Type.Name.ToLower())
{
case "string":
// Make all strings nullable in staging for data quality issues
column.IsNullable = true;
break;
case "datetime":
// Convert all dates to string in staging for problematic data
column.Type = typeof(string);
column.Length = 50;
break;
case "decimal":
// Convert decimals to strings to avoid precision issues during staging
column.Type = typeof(string);
column.Length = 50;
break;
}
return column;
}
Integration with DynamicWeb UI
The UI would need minor updates to support this:
TableMappingSaveCommand.cs
// Instead of just using source table name, call the interface
if (mapping.Job.Destination is ISameAsSourceProvider sameAsSourceProvider)
{
var customSchema = sameAsSourceProvider.CreateDestinationSchemaFromSource(
JobSchemaService.GetSchema(mapping.Job.Source),
destinationTableName
);
// Use the custom schema instead of direct copy
JobHelper.AddCustomSchemaToDestinationMapping(mapping, customSchema);
}
Benefits of This Approach
1. Complete Control: Transform table names, column names, data types
2. Staging-Specific Logic: Add audit columns, change nullability, etc.
3. Data Quality: Convert problematic types to strings for staging
4. Flexibility: Different providers can implement different transformation logic
5. Backward Compatibility: Existing file providers just return sourceSchema.Clone()
Advanced Use Cases You Could Implement
- Prefix/Suffix Table Names: Staging_Products, Products_Temp
- Add Metadata Columns: Load dates, batch IDs, source tracking
- Data Type Safety: Convert all to strings for staging, then transform later
- Schema Versioning: Add version columns for change tracking
- Partitioning Support: Add date partition columns
- Error Handling Columns: Add columns for data quality flags
Some more changes needed for the UI to work similar:
1. Create New Function in ProviderExtensions.cs
// ADD this new function alongside the existing IsFileProvider
private static bool SupportsSameAsSourceBehavior(Type type)
{
// Check if implements our new interface
if (typeof(ISameAsSourceProvider).IsAssignableFrom(type))
return true;
// Legacy support: existing file providers also support this behavior
return IsFileProvider(type);
}
// ADD new extension method
public static bool SupportsSameAsSourceBehavior(this IDestination destination)
{
Ensure.NotNull(destination);
return SupportsSameAsSourceBehavior(destination.GetType());
}
2. Update Usage Sites to Use New Function
Instead of changing every place that calls IsDestinationFileProvider(), we update them to use our new function:
IntegrationMappingProfile.cs:
// INSTEAD OF:
if (mapping.Job.Destination.IsDestinationFileProvider())
// USE:
if (mapping.Job.Destination.SupportsSameAsSourceBehavior()) or (mapping.Job.Destination.IsDestinationFileProvider())
ActivityMappingsListScreen.cs:
// INSTEAD OF:
bool isDestinationFileProvider = Job?.Destination?.IsDestinationFileProvider() ?? false;
// USE:
bool supportsSameAsSource = (Job?.Destination?.SupportsSameAsSourceBehavior() or Job?.Destination?.IsDestinationFileProvider()) ?? false;
