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reflect.go
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reflect.go
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package queries
import (
"database/sql"
"fmt"
"reflect"
"strings"
"sync"
"github.com/pkg/errors"
"github.com/vattle/sqlboiler/boil"
"github.com/vattle/sqlboiler/strmangle"
)
var (
bindAccepts = []reflect.Kind{reflect.Ptr, reflect.Slice, reflect.Ptr, reflect.Struct}
mut sync.RWMutex
bindingMaps = make(map[string][]uint64)
structMaps = make(map[string]map[string]uint64)
)
// Identifies what kind of object we're binding to
type bindKind int
const (
kindStruct bindKind = iota
kindSliceStruct
kindPtrSliceStruct
)
const (
loadMethodPrefix = "Load"
relationshipStructName = "R"
loaderStructName = "L"
sentinel = uint64(255)
)
// BindP executes the query and inserts the
// result into the passed in object pointer.
// It panics on error. See boil.Bind() documentation.
func (q *Query) BindP(obj interface{}) {
if err := q.Bind(obj); err != nil {
panic(boil.WrapErr(err))
}
}
// Bind executes the query and inserts the
// result into the passed in object pointer
//
// Bind rules:
// - Struct tags control bind, in the form of: `boil:"name,bind"`
// - If "name" is omitted the sql column names that come back are TitleCased
// and matched against the field name.
// - If the "name" part of the struct tag is specified, the given name will
// be used instead of the struct field name for binding.
// - If the "name" of the struct tag is "-", this field will not be bound to.
// - If the ",bind" option is specified on a struct field and that field
// is a struct itself, it will be recursed into to look for fields for binding.
//
// Example Query:
//
// type JoinStruct struct {
// // User1 can have it's struct fields bound to since it specifies
// // ,bind in the struct tag, it will look specifically for
// // fields that are prefixed with "user." returning from the query.
// // For example "user.id" column name will bind to User1.ID
// User1 *models.User `boil:"user,bind"`
// // User2 will follow the same rules as noted above except it will use
// // "friend." as the prefix it's looking for.
// User2 *models.User `boil:"friend,bind"`
// // RandomData will not be recursed into to look for fields to
// // bind and will not be bound to because of the - for the name.
// RandomData myStruct `boil:"-"`
// // Date will not be recursed into to look for fields to bind because
// // it does not specify ,bind in the struct tag. But it can be bound to
// // as it does not specify a - for the name.
// Date time.Time
// }
//
// models.Users(qm.InnerJoin("users as friend on users.friend_id = friend.id")).Bind(&joinStruct)
//
// For custom objects that want to use eager loading, please see the
// loadRelationships function.
func Bind(rows *sql.Rows, obj interface{}) error {
structType, sliceType, singular, err := bindChecks(obj)
if err != nil {
return err
}
return bind(rows, obj, structType, sliceType, singular)
}
// Bind executes the query and inserts the
// result into the passed in object pointer
//
// See documentation for boil.Bind()
func (q *Query) Bind(obj interface{}) error {
structType, sliceType, bkind, err := bindChecks(obj)
if err != nil {
return err
}
rows, err := q.Query()
if err != nil {
return errors.Wrap(err, "bind failed to execute query")
}
defer rows.Close()
if res := bind(rows, obj, structType, sliceType, bkind); res != nil {
return res
}
if len(q.load) != 0 {
return eagerLoad(q.executor, q.load, obj, bkind)
}
return nil
}
// bindChecks resolves information about the bind target, and errors if it's not an object
// we can bind to.
func bindChecks(obj interface{}) (structType reflect.Type, sliceType reflect.Type, bkind bindKind, err error) {
typ := reflect.TypeOf(obj)
kind := typ.Kind()
setErr := func() {
err = errors.Errorf("obj type should be *Type, *[]Type, or *[]*Type but was %q", reflect.TypeOf(obj).String())
}
for i := 0; ; i++ {
switch i {
case 0:
if kind != reflect.Ptr {
setErr()
return
}
case 1:
switch kind {
case reflect.Struct:
structType = typ
bkind = kindStruct
return
case reflect.Slice:
sliceType = typ
default:
setErr()
return
}
case 2:
switch kind {
case reflect.Struct:
structType = typ
bkind = kindSliceStruct
return
case reflect.Ptr:
default:
setErr()
return
}
case 3:
if kind != reflect.Struct {
setErr()
return
}
structType = typ
bkind = kindPtrSliceStruct
return
}
typ = typ.Elem()
kind = typ.Kind()
}
}
func bind(rows *sql.Rows, obj interface{}, structType, sliceType reflect.Type, bkind bindKind) error {
cols, err := rows.Columns()
if err != nil {
return errors.Wrap(err, "bind failed to get column names")
}
var ptrSlice reflect.Value
switch bkind {
case kindSliceStruct, kindPtrSliceStruct:
ptrSlice = reflect.Indirect(reflect.ValueOf(obj))
}
var strMapping map[string]uint64
var sok bool
var mapping []uint64
var ok bool
typStr := structType.String()
mapKey := makeCacheKey(typStr, cols)
mut.RLock()
mapping, ok = bindingMaps[mapKey]
if !ok {
if strMapping, sok = structMaps[typStr]; !sok {
strMapping = MakeStructMapping(structType)
}
}
mut.RUnlock()
if !ok {
mapping, err = BindMapping(structType, strMapping, cols)
if err != nil {
return err
}
mut.Lock()
if !sok {
structMaps[typStr] = strMapping
}
bindingMaps[mapKey] = mapping
mut.Unlock()
}
var oneStruct reflect.Value
if bkind == kindSliceStruct {
oneStruct = reflect.Indirect(reflect.New(structType))
}
foundOne := false
for rows.Next() {
foundOne = true
var newStruct reflect.Value
var pointers []interface{}
switch bkind {
case kindStruct:
pointers = PtrsFromMapping(reflect.Indirect(reflect.ValueOf(obj)), mapping)
case kindSliceStruct:
pointers = PtrsFromMapping(oneStruct, mapping)
case kindPtrSliceStruct:
newStruct = reflect.New(structType)
pointers = PtrsFromMapping(reflect.Indirect(newStruct), mapping)
}
if err != nil {
return err
}
if err := rows.Scan(pointers...); err != nil {
return errors.Wrap(err, "failed to bind pointers to obj")
}
switch bkind {
case kindSliceStruct:
ptrSlice.Set(reflect.Append(ptrSlice, oneStruct))
case kindPtrSliceStruct:
ptrSlice.Set(reflect.Append(ptrSlice, newStruct))
}
}
if bkind == kindStruct && !foundOne {
return sql.ErrNoRows
}
return nil
}
// BindMapping creates a mapping that helps look up the pointer for the
// column given.
func BindMapping(typ reflect.Type, mapping map[string]uint64, cols []string) ([]uint64, error) {
ptrs := make([]uint64, len(cols))
ColLoop:
for i, c := range cols {
name := strmangle.TitleCaseIdentifier(c)
ptrMap, ok := mapping[name]
if ok {
ptrs[i] = ptrMap
continue
}
suffix := "." + name
for maybeMatch, mapping := range mapping {
if strings.HasSuffix(maybeMatch, suffix) {
ptrs[i] = mapping
continue ColLoop
}
}
return nil, errors.Errorf("could not find struct field name in mapping: %s", name)
}
return ptrs, nil
}
// PtrsFromMapping expects to be passed an addressable struct and a mapping
// of where to find things. It pulls the pointers out referred to by the mapping.
func PtrsFromMapping(val reflect.Value, mapping []uint64) []interface{} {
ptrs := make([]interface{}, len(mapping))
for i, m := range mapping {
ptrs[i] = ptrFromMapping(val, m, true).Interface()
}
return ptrs
}
// ValuesFromMapping expects to be passed an addressable struct and a mapping
// of where to find things. It pulls the pointers out referred to by the mapping.
func ValuesFromMapping(val reflect.Value, mapping []uint64) []interface{} {
ptrs := make([]interface{}, len(mapping))
for i, m := range mapping {
ptrs[i] = ptrFromMapping(val, m, false).Interface()
}
return ptrs
}
// ptrFromMapping expects to be passed an addressable struct that it's looking
// for things on.
func ptrFromMapping(val reflect.Value, mapping uint64, addressOf bool) reflect.Value {
for i := 0; i < 8; i++ {
v := (mapping >> uint(i*8)) & sentinel
if v == sentinel {
if addressOf && val.Kind() != reflect.Ptr {
return val.Addr()
} else if !addressOf && val.Kind() == reflect.Ptr {
return reflect.Indirect(val)
}
return val
}
val = val.Field(int(v))
if val.Kind() == reflect.Ptr {
val = reflect.Indirect(val)
}
}
panic("could not find pointer from mapping")
}
// MakeStructMapping creates a map of the struct to be able to quickly look
// up its pointers and values by name.
func MakeStructMapping(typ reflect.Type) map[string]uint64 {
fieldMaps := make(map[string]uint64)
makeStructMappingHelper(typ, "", 0, 0, fieldMaps)
return fieldMaps
}
func makeStructMappingHelper(typ reflect.Type, prefix string, current uint64, depth uint, fieldMaps map[string]uint64) {
if typ.Kind() == reflect.Ptr {
typ = typ.Elem()
}
n := typ.NumField()
for i := 0; i < n; i++ {
f := typ.Field(i)
tag, recurse := getBoilTag(f)
if len(tag) == 0 {
tag = f.Name
} else if tag[0] == '-' {
continue
}
if len(prefix) != 0 {
tag = fmt.Sprintf("%s.%s", prefix, tag)
}
if recurse {
makeStructMappingHelper(f.Type, tag, current|uint64(i)<<depth, depth+8, fieldMaps)
continue
}
fieldMaps[tag] = current | (sentinel << (depth + 8)) | (uint64(i) << depth)
}
}
func getBoilTag(field reflect.StructField) (name string, recurse bool) {
tag := field.Tag.Get("boil")
name = field.Name
if len(tag) == 0 {
return name, false
}
ind := strings.IndexByte(tag, ',')
if ind == -1 {
return strmangle.TitleCase(tag), false
} else if ind == 0 {
return name, true
}
nameFragment := tag[:ind]
return strmangle.TitleCase(nameFragment), true
}
func makeCacheKey(typ string, cols []string) string {
buf := strmangle.GetBuffer()
buf.WriteString(typ)
for _, s := range cols {
buf.WriteString(s)
}
mapKey := buf.String()
strmangle.PutBuffer(buf)
return mapKey
}