public class FieldRemappings extends Object
Modifier and Type | Class and Description |
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static class |
FieldRemappings.Directive
A mapping directive to be applied to a source field.
|
Constructor and Description |
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FieldRemappings() |
Modifier and Type | Method and Description |
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static FieldRemappings.Directive |
drop(String name)
Declares a source field is to be omitted from the result.
|
static FieldRemappings.Directive |
keep(String name)
Declares a source field is to be preserved in the result,
keeping the same name.
|
static FieldRemappings.Directive |
map(String from,
String to)
Defines a name mapping from a source to a target field.
|
static FieldRemapping |
patternRename(String format,
String... excludedFields)
Defines a simple pattern-based renaming fields of a record schema.
|
static FieldRemapping |
rename(FieldRemappings.Directive... directives)
Defines a transformation renaming fields of a record schema.
|
static FieldRemapping |
renameAndDrop(FieldRemappings.Directive... directives)
Defines a transformation renaming fields of a record schema,
dropping source fields without an explicit directive.
|
static FieldRemapping |
reorder(FieldRemappings.Directive... directives)
Defines a transformation reordering and possibly renaming fields of
a record schema.
|
static FieldRemapping |
reorderAndDrop(FieldRemappings.Directive... directives)
Defines a transformation reordering and possibly renaming fields of
a record schema, dropping source fields without an explicit directive.
|
public static FieldRemappings.Directive drop(String name)
This is useful is forcibly removing fields from the source
when they otherwise would be kept, for example when using
rename(Directive...)
or reorder(Directive...)
.
If the only actions being done are the dropping of unwanted
fields, consider using one of SelectFields
,
RetainFields
, or RemoveFields
.
name
- the name of the source field to drop from the targetpublic static FieldRemappings.Directive keep(String name)
This is useful if renaming is not desired, but a mapping is needed to produce desired ordering or preserve a field in a type mapping.
name
- the name of the source field to keep in the targetpublic static FieldRemappings.Directive map(String from, String to)
from
- the name of the field in the sourceto
- the name of the field in the targetpublic static FieldRemapping patternRename(String format, String... excludedFields)
format
- a pattern for renaming of fields. This is in the
syntax supported by MessageFormat
. There will be exactly
one argument to format - the name of the field.excludedFields
- names of fields which should not be
be renamed.public static FieldRemapping rename(FieldRemappings.Directive... directives)
For example, if the source schema is {"a", "b", "c"} and the directives [ "c"->"Z", "a"->"X" ] are applied, the result is { "X", "b", "Z" }.
Note that in this context, a keep(java.lang.String)
directive
is a no-op.
directives
- the field mapping operations to apply.public static FieldRemapping renameAndDrop(FieldRemappings.Directive... directives)
For example, if the source schema is {"a", "b", "c"} and the directives [ "c"->"Z", "a"->"X" ] are applied, the result is { "X", "Z" }.
Note that in this context, a drop(java.lang.String)
directive
is a no-op. Further, this transformation is equivalent to
combining a rename operation with a RetainFields
.
directives
- the field mapping operations to apply.public static FieldRemapping reorder(FieldRemappings.Directive... directives)
Unlike rename(Directive...)
, a keep(java.lang.String)
directive does exhibit an effect, controlling the ordering
of a field in the result.
directives
- the field mapping operations to apply.public static FieldRemapping reorderAndDrop(FieldRemappings.Directive... directives)
As an example, if the source schema is {"a", "b", "c"} and the directives [ "c"->"Z", "a"->"X" ] are applied, the result is { "Z", "X" }.
Note that in this context, a drop(java.lang.String)
directive
is a no-op. Further, this transformation is equivalent to
combining a renaming operation with a SelectFields
.
directives
- the field mapping operations to apply.Copyright © 2016 Actian Corporation. All rights reserved.