MetadataDefaultsProvider Class

Overview

The MetadataDefaultsProvider class is the concrete implementation of IDataTypeDefaultValueProvider in the PocoDataSet.Data assembly. It provides a dependency-injection-friendly entry point for resolving default values for newly created cells based on a column's logical data type and nullability.

Internally, MetadataDefaultsProvider delegates all default-value decisions to the static MetadataDefaults helper. This keeps defaulting rules centralized while allowing higher-level components (factories, UI frameworks, adapters) to depend on an interface rather than calling static methods directly.

Namespace and Assembly

Namespace: PocoDataSet.Data
Assembly: PocoDataSet.Data.dll

Declaration

public class MetadataDefaultsProvider : IDataTypeDefaultValueProvider
{
    public object? GetDefaultValue(string? dataType, bool isNullable)
    {
        return MetadataDefaults.GetDefaultValue(dataType, isNullable);
    }
}

Method Notes

• GetDefaultValue returns the default value for the specified logical dataType (typically a value from DataTypeNames) and the isNullable flag.
• If isNullable is true, many consumers choose to keep the cell value as null; the exact rule is determined by MetadataDefaults.
• MetadataDefaultsProvider contains no defaulting logic of its own; it exists so default value resolution can be swapped or mocked in tests.

Usage Example

// Example: resolving a default value from column metadata
IDataTypeDefaultValueProvider provider = new MetadataDefaultsProvider();

// Suppose the column is an INT32 and not nullable
object? defaultValue = provider.GetDefaultValue(DataTypeNames.INT32, false);

// defaultValue can now be assigned to a newly created cell
// (exact value depends on MetadataDefaults rules)

Design Notes

Use MetadataDefaults directly when a static call is sufficient (for example, in simple extension methods). Use MetadataDefaultsProvider when you want an interface boundary for dependency injection, unit testing, or alternative strategies.

 

Table of Content POCO DataSet PocoDataSet.Data

 

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Business Process Programming in .Net
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