Documentation
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Index ¶
- Constants
- Variables
- func IsBadMappingErr(err error) bool
- func IsNecessary(srcSch, destSch schema.Schema, destToSrc map[uint64]uint64) (bool, error)
- type BadMappingErr
- type ColNamingFunc
- type FieldMapping
- func IdentityMapping(sch schema.Schema) *FieldMapping
- func InvertMapping(fm *FieldMapping) *FieldMapping
- func NameMapping(srcSch, destSch schema.Schema, nameMapper NameMapper) (*FieldMapping, error)
- func NewFieldMapping(srcSch, destSch schema.Schema, srcTagToDestTag map[uint64]uint64) (*FieldMapping, error)
- func TagMapping(srcSch, destSch schema.Schema) (*FieldMapping, error)
- func TagMappingWithNameFallback(srcSch, destSch schema.Schema) (*FieldMapping, error)
- func TypedToUntypedMapping(sch schema.Schema) (*FieldMapping, error)
- type Joiner
- type NameMapper
- type NamedSchema
- type RowConverter
- type WarnFunction
Constants ¶
const DatatypeCoercionFailureWarningCode int = 1105 // Since this our own custom warning we'll use 1105, the code for an unknown error
Variables ¶
var DatatypeCoercionFailureWarning = "unable to coerce value from field '%s' into latest column schema"
var ErrEmptyMapping = errors.New("empty mapping error")
ErrEmptyMapping is an error returned when the mapping is empty (No src columns, no destination columns)
var ErrMappingFileRead = errors.New("error reading mapping file")
ErrMappingFileRead is an error returned when a mapping file cannot be read
var ErrUnmarshallingMapping = errors.New("error unmarshalling mapping")
ErrUnmarshallingMapping is an error used when a mapping file cannot be converted from json
var IdentityConverter = &RowConverter{nil, true, nil}
Functions ¶
func IsBadMappingErr ¶
IsBadMappingErr returns true if the error is a BadMappingErr
Types ¶
type BadMappingErr ¶
type BadMappingErr struct {
// contains filtered or unexported fields
}
BadMappingErr is a struct which implements the error interface and is used when there is an error with a mapping.
func (*BadMappingErr) Error ¶
func (err *BadMappingErr) Error() string
String representing the BadMappingError
type ColNamingFunc ¶
ColNamingFunc defines a function signature which takes the name of a column, and returns the name that should be used for the column in the joined dataset.
type FieldMapping ¶
type FieldMapping struct {
// SrcSch is the source schema being mapped from.
SrcSch schema.Schema
// DestSch is the destination schema being mapped to.
DestSch schema.Schema
// SrcToDest is a map from a tag in the source schema to a tag in the dest schema.
SrcToDest map[uint64]uint64
}
FieldMapping defines a mapping from columns in a source schema to columns in a dest schema.
func IdentityMapping ¶
func IdentityMapping(sch schema.Schema) *FieldMapping
Returns the identity mapping for the schema given.
func InvertMapping ¶
func InvertMapping(fm *FieldMapping) *FieldMapping
func NameMapping ¶
func NameMapping(srcSch, destSch schema.Schema, nameMapper NameMapper) (*FieldMapping, error)
NameMapping takes a source schema and a destination schema and maps all columns which have a matching name in the source and destination schemas.
func NewFieldMapping ¶
func NewFieldMapping(srcSch, destSch schema.Schema, srcTagToDestTag map[uint64]uint64) (*FieldMapping, error)
NewFieldMapping creates a FieldMapping from a source schema, a destination schema, and a map from tags in the source schema to tags in the dest schema.
func TagMapping ¶
func TagMapping(srcSch, destSch schema.Schema) (*FieldMapping, error)
TagMapping takes a source schema and a destination schema and maps all columns which have a matching tag in the source and destination schemas.
func TagMappingWithNameFallback ¶
func TagMappingWithNameFallback(srcSch, destSch schema.Schema) (*FieldMapping, error)
TagMappingWithNameFallback takes a source schema and a destination schema and maps columns by matching tags first, then attempts to match by column name for any columns that didn't match with an exact tag.
func TypedToUntypedMapping ¶
func TypedToUntypedMapping(sch schema.Schema) (*FieldMapping, error)
TypedToUntypedMapping takes a schema and creates a mapping to an untyped schema with all the same columns.
func (*FieldMapping) MapsAllDestPKs ¶
func (fm *FieldMapping) MapsAllDestPKs() bool
MapsAllDestPKs checks that each PK column in DestSch has a corresponding column in SrcSch
type Joiner ¶
type Joiner struct {
// contains filtered or unexported fields
}
Joiner is an object that can be used to join multiple rows together into a single row (See Join), and also to reverse this operation by taking a joined row and getting back a map of rows (See Split).
func NewJoiner ¶
func NewJoiner(namedSchemas []NamedSchema, namers map[string]ColNamingFunc) (*Joiner, error)
NewJoiner creates a joiner from a slice of NamedSchemas and a map of ColNamingFuncs. A new schema for joined rows will be created, and the columns for joined schemas will be named according to the ColNamingFunc associated with each schema name.
func (*Joiner) GetSchema ¶
GetSchema returns the schema which all joined rows will have, and any row passed into split should have.
func (*Joiner) Join ¶
Join takes a map from schema name to row which has that schema, and returns a single joined row containing all the data
func (*Joiner) SchemaForName ¶
SchemaForName retrieves the original schema which has the given name.
type NameMapper ¶
NameMapper is a simple interface for mapping a string to another string
func NameMapperFromFile ¶
func NameMapperFromFile(mappingFile string, FS filesys.ReadableFS) (NameMapper, error)
NameMapperFromFile reads a JSON file containing a name mapping and returns a NameMapper.
func (NameMapper) Map ¶
func (nm NameMapper) Map(str string) string
Map maps a string to another string. If a string is not in the mapping ok will be false, otherwise it is true.
func (NameMapper) PreImage ¶
func (nm NameMapper) PreImage(str string) string
PreImage searches the NameMapper for the string that maps to str, returns str otherwise
type NamedSchema ¶
type NamedSchema struct {
// Name the name given to the schema
Name string
// Sch is the schema
Sch schema.Schema
}
NamedSchema is an object that associates a schema with a string
type RowConverter ¶
type RowConverter struct {
// FieldMapping is a mapping from source column to destination column
*FieldMapping
// IdentityConverter is a bool which is true if the converter is doing nothing.
IdentityConverter bool
ConvFuncs map[uint64]types.MarshalCallback
}
RowConverter converts rows from one schema to another
func NewRowConverter ¶
func NewRowConverter(ctx context.Context, vrw types.ValueReadWriter, mapping *FieldMapping) (*RowConverter, error)
NewRowConverter creates a row converter from a given FieldMapping.
func (*RowConverter) Convert ¶
Convert takes an input row, maps its columns to destination columns, and performs any type conversion needed to create a row of the expected destination schema.
func (*RowConverter) ConvertWithWarnings ¶
func (rc *RowConverter) ConvertWithWarnings(inRow row.Row, warnFn WarnFunction) (row.Row, error)
ConvertWithWarnings takes an input row, maps its columns to their destination columns, performing any type conversions needed to create a row of the expected destination schema, and uses the optional WarnFunction callback to let callers handle logging a warning when a field cannot be cleanly converted.
type WarnFunction ¶
WarnFunction is a callback function that callers can optionally provide during row conversion to take an extra action when a value cannot be automatically converted to the output data type.
Source Files