Interface IColumnMapperCommand

This interface contains commands for mapping columns from a source row to a target row. The source and target can be different from each other, and might be tables, queries etc. in external data sources, or fields and properties in .NET CLR types. It is often used as a worker parameter or property, to allow the user to specify which columns to map or copy. The worker then uses TypeColumnMapper<TFrom, TTo>, FromTypeColumnMapper<TFrom>, or ToTypeColumnMapper<TTo> to create mappings and perform the copying etc. itself. Also see TypeColumnCopier<TFrom, TTo>, which allows generating high performance copying delegates.

This interface does not include the Row() method, and should be used when the Row() method is not supported by the worker in question. Also see IRowMapperCommand which does include that method.

See Dataflow Column Mapping and Mapping and Copying for more details.

Note: If the mapping commands result in duplicate mappings, an exception will be thrown. Resolve this by either of:

  • Specify additional or all name parts in explicit mapping
  • Change the column (or schema) names in the from and/or to rows to avoid name clashes
  • Restrict auto-mapping to specific column schemas
  • Map offending columns explicitly by name (which will exclude them from later auto-mappings)

Inherited Members
Namespace: actionETL
Assembly: actionETL.dll
Syntax
public interface IColumnMapperCommand : IFluentInterface

Methods

AutoName()

Map automatically by name. Identical names will match, as will partial names where one or more of the left-most parts of the name have been left out. E.g., "Person.Name.FirstName" would automatically map to either of "FirstName" and "Name.FirstName". More matching parts take precedence over fewer matching parts.

Column name matching is ordinal case insensitive, but a case sensitive match takes precedence over a case insensitive match.

The mapping only considers readable (see CanRead) 'from' columns and writable (see CanWrite) 'to' columns.

Note: If there are still more than one possible mapping, an exception will be thrown. Resolve this by either of:

  • Change the column names in the row(s) to avoid name clashes
  • Use one of the overloads that allows restricting the auto-mapping to specific hierarchy names
  • Map offending columns individually by name (which will exclude them from later mappings), before calling this auto-mapping method

Declaration
IColumnMapperCommand AutoName()
Returns
Type Description
IColumnMapperCommand

The IColumnMapperCommand instance itself, which allows chaining commands.
Exceptions
Type Condition
InvalidOperationException
  • Duplicate matches.

AutoName(Int32)

Map automatically by name. Identical names will match, as will partial names where one or more of the left-most parts of the name have been left out. E.g., "Person.Name.FirstName" would automatically map to either of "FirstName" and "Name.FirstName". More matching parts take precedence over fewer matching parts.

Column name matching is ordinal case insensitive, but a case sensitive match takes precedence over a case insensitive match.

The mapping only considers readable (see CanRead) 'from' columns and writable (see CanWrite) 'to' columns.

Note: If there are still more than one possible mapping, an exception will be thrown. Resolve this by either of:

  • Change the column names in the row(s) to avoid name clashes
  • Use one of the overloads that allows restricting the auto-mapping to specific hierarchy names
  • Map offending columns individually by name (which will exclude them from later mappings), before calling this auto-mapping method

Declaration
IColumnMapperCommand AutoName(int assertNumberOfMatches)
Parameters
Type Name Description
Int32 assertNumberOfMatches

Assert number of matches.
Returns
Type Description
IColumnMapperCommand

The IColumnMapperCommand instance itself, which allows chaining commands.
Exceptions
Type Condition
InvalidOperationException
  • Duplicate matches.

AutoName(Int32, String, String)

Map automatically by name. Identical names will match, as will partial names where one or more of the left-most parts of the name have been left out. E.g., "Person.Name.FirstName" would automatically map to either of "FirstName" and "Name.FirstName". More matching parts take precedence over fewer matching parts.

Column name matching is ordinal case insensitive, but a case sensitive match takes precedence over a case insensitive match.

The mapping only considers readable (see CanRead) 'from' columns and writable (see CanWrite) 'to' columns.

Note: If there are still more than one possible mapping, an exception will be thrown. Resolve this by either of:

  • Change the column names in the row(s) to avoid name clashes
  • Restrict the auto-mapping to specific hierarchy names
  • Map offending columns individually by name (which will exclude them from later mappings), before calling this auto-mapping method

Declaration
IColumnMapperCommand AutoName(int assertNumberOfMatches, string fromHierarchyName, string toHierarchyName)
Parameters
Type Name Description
Int32 assertNumberOfMatches

Assert number of matches.
String fromHierarchyName

Hierarchy from name to include, or null to include all members. Name parts can be omitted from the right, e.g. specifying "Person" will only auto-map from the "Person" member residing directly in the root of the row class, and any descendants of "Person".
String toHierarchyName

Hierarchy to name to include, or null to include all members. Name parts can be omitted from the right, e.g. specifying "Person" will only auto-map to the "Person" member residing directly in the root of the row class, and any descendants of "Person".
Returns
Type Description
IColumnMapperCommand

The IColumnMapperCommand instance itself, which allows chaining commands.
Exceptions
Type Condition
InvalidOperationException
  • Duplicate matches.

AutoName(String, String)

Map automatically by name. Identical names will match, as will partial names where one or more of the left-most parts of the name have been left out. E.g., "Person.Name.FirstName" would automatically map to either of "FirstName" and "Name.FirstName". More matching parts take precedence over fewer matching parts.

Column name matching is ordinal case insensitive, but a case sensitive match takes precedence over a case insensitive match.

The mapping only considers readable (see CanRead) 'from' columns and writable (see CanWrite) 'to' columns.

Note: If there are still more than one possible mapping, an exception will be thrown. Resolve this by either of:

  • Change the column names in the row(s) to avoid name clashes
  • Restrict the auto-mapping to specific hierarchy names
  • Map offending columns individually by name (which will exclude them from later mappings), before calling this auto-mapping method

Declaration
IColumnMapperCommand AutoName(string fromHierarchyName, string toHierarchyName)
Parameters
Type Name Description
String fromHierarchyName

Hierarchy from name to include, or null to include all members. Name parts can be omitted from the right, e.g. specifying "Person" will only auto-map from the "Person" member residing directly in the root of the row class, and any descendants of "Person".
String toHierarchyName

Hierarchy to name to include, or null to include all members. Name parts can be omitted from the right, e.g. specifying "Person" will only auto-map to the "Person" member residing directly in the root of the row class, and any descendants of "Person".
Returns
Type Description
IColumnMapperCommand

The IColumnMapperCommand instance itself, which allows chaining commands.
Exceptions
Type Condition
InvalidOperationException
  • Duplicate matches.

Index(Int32, Int32)

Map a 'from' column to a 'to' column based on their index in SchemaNodeList.

Declaration
IColumnMapperCommand Index(int fromSchemaNodeListIndex, int toSchemaNodeListIndex)
Parameters
Type Name Description
Int32 fromSchemaNodeListIndex

From index.
Int32 toSchemaNodeListIndex

To index.
Returns
Type Description
IColumnMapperCommand

The IColumnMapperCommand instance itself, which allows chaining commands.
Exceptions
Type Condition
ArgumentOutOfRangeException

schemaNodeListIndex was outside [0, number of items).
InvalidOperationException
  • Column already mapped
  • Duplicate column mappings

Name(String)

Map a 'from' column to a 'to' column based on their names.

Column name matching is ordinal case insensitive, but a case sensitive match takes precedence over a case insensitive match.

Declaration
IColumnMapperCommand Name(string schemaNodeName)
Parameters
Type Name Description
String schemaNodeName

Name of both the 'from' and 'to' columns. Column schema names can optionally be omitted from the left, as long as the specified name is unique among all columns in the row. E.g., assuming "FirstName" is unique, the following can all identify the same column:

  • "Person.Name.FirstName"
  • "Name.FirstName"
  • "FirstName"
Returns
Type Description
IColumnMapperCommand

The IColumnMapperCommand instance itself, which allows chaining commands.
Exceptions
Type Condition
InvalidOperationException
  • Member not found
  • Found more than one member match in type
  • Name already mapped
ArgumentNullException

schemaNodeName

Name(String, String)

Map a 'from' column to a 'to' column based on their names.

Column name matching is ordinal case insensitive, but a case sensitive match takes precedence over a case insensitive match.

Declaration
IColumnMapperCommand Name(string fromSchemaNodeName, string toSchemaNodeName)
Parameters
Type Name Description
String fromSchemaNodeName

Name of the 'from' column. Column schema names can optionally be omitted from the left, as long as the specified name is unique among all columns in the row. E.g., assuming "FirstName" is unique, the following can all identify the same column:

  • "Person.Name.FirstName"
  • "Name.FirstName"
  • "FirstName"
String toSchemaNodeName

Name of the 'to' column. Column schema names can optionally be omitted from the left, as long as the specified name is unique among all columns in the row. E.g., assuming "FirstName" is unique, the following can all identify the same column:

  • "Person.Name.FirstName"
  • "Name.FirstName"
  • "FirstName"
Returns
Type Description
IColumnMapperCommand

The IColumnMapperCommand instance itself, which allows chaining commands.
Exceptions
Type Condition
InvalidOperationException
  • Member not found
  • Found more than one member match in type
  • Name already mapped
ArgumentNullException
  • fromSchemaNodeName
  • toSchemaNodeName

See Also

TypeColumnMapper<TFrom, TTo>
TypeColumnCopier<TFrom, TTo>