README
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reflectx
The sqlx package has special reflect needs. In particular, it needs to:
- be able to map a name to a field
- understand embedded structs
- understand mapping names to fields by a particular tag
- user specified name -> field mapping functions
These behaviors mimic the behaviors by the standard library marshallers and also the behavior of standard Go accessors.
The first two are amply taken care of by Reflect.Value.FieldByName, and the third is
addressed by Reflect.Value.FieldByNameFunc, but these don't quite understand struct
tags in the ways that are vital to most marshallers, and they are slow.
This reflectx package extends reflect to achieve these goals.
Documentation
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Overview ¶
Package reflectx implements extensions to the standard reflect lib suitable for implementing marshalling and unmarshalling packages. The main Mapper type allows for Go-compatible named attribute access, including accessing embedded struct attributes and the ability to use functions and struct tags to customize field names.
Index ¶
- func Deref(t reflect.Type) reflect.Type
- func FieldByIndexes(v reflect.Value, indexes []int) reflect.Value
- func FieldByIndexesReadOnly(v reflect.Value, indexes []int) reflect.Value
- type FieldInfo
- type Mapper
- func (m *Mapper) FieldByName(v reflect.Value, name string) reflect.Value
- func (m *Mapper) FieldMap(v reflect.Value) map[string]reflect.Value
- func (m *Mapper) FieldsByName(v reflect.Value, names []string) []reflect.Value
- func (m *Mapper) TraversalsByName(t reflect.Type, names []string) [][]int
- func (m *Mapper) TraversalsByNameFunc(t reflect.Type, names []string, fn func(int, []int) error) error
- func (m *Mapper) TypeMap(t reflect.Type) *StructMap
- type StructMap
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func FieldByIndexes ¶
FieldByIndexes returns a value for the field given by the struct traversal for the given value.
Types ¶
type FieldInfo ¶
type FieldInfo struct {
Index []int
Path string
Field reflect.StructField
Zero reflect.Value
Name string
Options map[string]string
Embedded bool
Children []*FieldInfo
Parent *FieldInfo
}
A FieldInfo is metadata for a struct field.
type Mapper ¶
type Mapper struct {
// contains filtered or unexported fields
}
Mapper is a general purpose mapper of names to struct fields. A Mapper behaves like most marshallers in the standard library, obeying a field tag for name mapping but also providing a basic transform function.
func NewMapper ¶
NewMapper returns a new mapper using the tagName as its struct field tag. If tagName is the empty string, it is ignored.
func NewMapperFunc ¶
NewMapperFunc returns a new mapper which optionally obeys a field tag and a struct field name mapper func given by f. Tags will take precedence, but for any other field, the mapped name will be f(field.Name)
func NewMapperTagFunc ¶
NewMapperTagFunc returns a new mapper which contains a mapper for field names AND a mapper for tag values. This is useful for tags like json which can have values like "name,omitempty".
func (*Mapper) FieldByName ¶
FieldByName returns a field by its mapped name as a reflect.Value. Panics if v's Kind is not Struct or v is not Indirectable to a struct Kind. Returns zero Value if the name is not found.
func (*Mapper) FieldMap ¶
FieldMap returns the mapper's mapping of field names to reflect values. Panics if v's Kind is not Struct, or v is not Indirectable to a struct kind.
func (*Mapper) FieldsByName ¶
FieldsByName returns a slice of values corresponding to the slice of names for the value. Panics if v's Kind is not Struct or v is not Indirectable to a struct Kind. Returns zero Value for each name not found.
func (*Mapper) TraversalsByName ¶
TraversalsByName returns a slice of int slices which represent the struct traversals for each mapped name. Panics if t is not a struct or Indirectable to a struct. Returns empty int slice for each name not found.
func (*Mapper) TraversalsByNameFunc ¶
func (m *Mapper) TraversalsByNameFunc(t reflect.Type, names []string, fn func(int, []int) error) error
TraversalsByNameFunc traverses the mapped names and calls fn with the index of each name and the struct traversal represented by that name. Panics if t is not a struct or Indirectable to a struct. Returns the first error returned by fn or nil.
type StructMap ¶
type StructMap struct {
Tree *FieldInfo
Index []*FieldInfo
Paths map[string]*FieldInfo
Names map[string]*FieldInfo
}
A StructMap is an index of field metadata for a struct.
func (StructMap) GetByTraversal ¶
GetByTraversal returns a *FieldInfo for a given integer path. It is analogous to reflect.FieldByIndex, but using the cached traversal rather than re-executing the reflect machinery each time.
Source Files