callback.go
package gorm
import "fmt"
// DefaultCallback default callbacks defined by gorm
var DefaultCallback = &Callback{logger: nopLogger{}}
// Callback is a struct that contains all CRUD callbacks
// Field `creates` contains callbacks will be call when creating object
// Field `updates` contains callbacks will be call when updating object
// Field `deletes` contains callbacks will be call when deleting object
// Field `queries` contains callbacks will be call when querying object with query methods like Find, First, Related, Association...
// Field `rowQueries` contains callbacks will be call when querying object with Row, Rows...
// Field `processors` contains all callback processors, will be used to generate above callbacks in order
type Callback struct {
logger logger
creates []*func(scope *Scope)
updates []*func(scope *Scope)
deletes []*func(scope *Scope)
queries []*func(scope *Scope)
rowQueries []*func(scope *Scope)
processors []*CallbackProcessor
}
// CallbackProcessor contains callback informations
type CallbackProcessor struct {
logger logger
name string // current callback's name
before string // register current callback before a callback
after string // register current callback after a callback
replace bool // replace callbacks with same name
remove bool // delete callbacks with same name
kind string // callback type: create, update, delete, query, row_query
processor *func(scope *Scope) // callback handler
parent *Callback
}
func (c *Callback) clone(logger logger) *Callback {
return &Callback{
logger: logger,
creates: c.creates,
updates: c.updates,
deletes: c.deletes,
queries: c.queries,
rowQueries: c.rowQueries,
processors: c.processors,
}
}
// Create could be used to register callbacks for creating object
// db.Callback().Create().After("gorm:create").Register("plugin:run_after_create", func(*Scope) {
// // business logic
// ...
//
// // set error if some thing wrong happened, will rollback the creating
// scope.Err(errors.New("error"))
// })
func (c *Callback) Create() *CallbackProcessor {
return &CallbackProcessor{logger: c.logger, kind: "create", parent: c}
}
// Update could be used to register callbacks for updating object, refer `Create` for usage
func (c *Callback) Update() *CallbackProcessor {
return &CallbackProcessor{logger: c.logger, kind: "update", parent: c}
}
// Delete could be used to register callbacks for deleting object, refer `Create` for usage
func (c *Callback) Delete() *CallbackProcessor {
return &CallbackProcessor{logger: c.logger, kind: "delete", parent: c}
}
// Query could be used to register callbacks for querying objects with query methods like `Find`, `First`, `Related`, `Association`...
// Refer `Create` for usage
func (c *Callback) Query() *CallbackProcessor {
return &CallbackProcessor{logger: c.logger, kind: "query", parent: c}
}
// RowQuery could be used to register callbacks for querying objects with `Row`, `Rows`, refer `Create` for usage
func (c *Callback) RowQuery() *CallbackProcessor {
return &CallbackProcessor{logger: c.logger, kind: "row_query", parent: c}
}
// After insert a new callback after callback `callbackName`, refer `Callbacks.Create`
func (cp *CallbackProcessor) After(callbackName string) *CallbackProcessor {
cp.after = callbackName
return cp
}
// Before insert a new callback before callback `callbackName`, refer `Callbacks.Create`
func (cp *CallbackProcessor) Before(callbackName string) *CallbackProcessor {
cp.before = callbackName
return cp
}
// Register a new callback, refer `Callbacks.Create`
func (cp *CallbackProcessor) Register(callbackName string, callback func(scope *Scope)) {
if cp.kind == "row_query" {
if cp.before == "" && cp.after == "" && callbackName != "gorm:row_query" {
cp.logger.Print("info", fmt.Sprintf("Registering RowQuery callback %v without specify order with Before(), After(), applying Before('gorm:row_query') by default for compatibility...", callbackName))
cp.before = "gorm:row_query"
}
}
cp.logger.Print("info", fmt.Sprintf("[info] registering callback `%v` from %v", callbackName, fileWithLineNum()))
cp.name = callbackName
cp.processor = &callback
cp.parent.processors = append(cp.parent.processors, cp)
cp.parent.reorder()
}
// Remove a registered callback
// db.Callback().Create().Remove("gorm:update_time_stamp_when_create")
func (cp *CallbackProcessor) Remove(callbackName string) {
cp.logger.Print("info", fmt.Sprintf("[info] removing callback `%v` from %v", callbackName, fileWithLineNum()))
cp.name = callbackName
cp.remove = true
cp.parent.processors = append(cp.parent.processors, cp)
cp.parent.reorder()
}
// Replace a registered callback with new callback
// db.Callback().Create().Replace("gorm:update_time_stamp_when_create", func(*Scope) {
// scope.SetColumn("CreatedAt", now)
// scope.SetColumn("UpdatedAt", now)
// })
func (cp *CallbackProcessor) Replace(callbackName string, callback func(scope *Scope)) {
cp.logger.Print("info", fmt.Sprintf("[info] replacing callback `%v` from %v", callbackName, fileWithLineNum()))
cp.name = callbackName
cp.processor = &callback
cp.replace = true
cp.parent.processors = append(cp.parent.processors, cp)
cp.parent.reorder()
}
// Get registered callback
// db.Callback().Create().Get("gorm:create")
func (cp *CallbackProcessor) Get(callbackName string) (callback func(scope *Scope)) {
for _, p := range cp.parent.processors {
if p.name == callbackName && p.kind == cp.kind {
if p.remove {
callback = nil
} else {
callback = *p.processor
}
}
}
return
}
// getRIndex get right index from string slice
func getRIndex(strs []string, str string) int {
for i := len(strs) - 1; i >= 0; i-- {
if strs[i] == str {
return i
}
}
return -1
}
// sortProcessors sort callback processors based on its before, after, remove, replace
func sortProcessors(cps []*CallbackProcessor) []*func(scope *Scope) {
var (
allNames, sortedNames []string
sortCallbackProcessor func(c *CallbackProcessor)
)
for _, cp := range cps {
// show warning message the callback name already exists
if index := getRIndex(allNames, cp.name); index > -1 && !cp.replace && !cp.remove {
cp.logger.Print("warning", fmt.Sprintf("[warning] duplicated callback `%v` from %v", cp.name, fileWithLineNum()))
}
allNames = append(allNames, cp.name)
}
sortCallbackProcessor = func(c *CallbackProcessor) {
if getRIndex(sortedNames, c.name) == -1 { // if not sorted
if c.before != "" { // if defined before callback
if index := getRIndex(sortedNames, c.before); index != -1 {
// if before callback already sorted, append current callback just after it
sortedNames = append(sortedNames[:index], append([]string{c.name}, sortedNames[index:]...)...)
} else if index := getRIndex(allNames, c.before); index != -1 {
// if before callback exists but haven't sorted, append current callback to last
sortedNames = append(sortedNames, c.name)
sortCallbackProcessor(cps[index])
}
}
if c.after != "" { // if defined after callback
if index := getRIndex(sortedNames, c.after); index != -1 {
// if after callback already sorted, append current callback just before it
sortedNames = append(sortedNames[:index+1], append([]string{c.name}, sortedNames[index+1:]...)...)
} else if index := getRIndex(allNames, c.after); index != -1 {
// if after callback exists but haven't sorted
cp := cps[index]
// set after callback's before callback to current callback
if cp.before == "" {
cp.before = c.name
}
sortCallbackProcessor(cp)
}
}
// if current callback haven't been sorted, append it to last
if getRIndex(sortedNames, c.name) == -1 {
sortedNames = append(sortedNames, c.name)
}
}
}
for _, cp := range cps {
sortCallbackProcessor(cp)
}
var sortedFuncs []*func(scope *Scope)
for _, name := range sortedNames {
if index := getRIndex(allNames, name); !cps[index].remove {
sortedFuncs = append(sortedFuncs, cps[index].processor)
}
}
return sortedFuncs
}
// reorder all registered processors, and reset CRUD callbacks
func (c *Callback) reorder() {
var creates, updates, deletes, queries, rowQueries []*CallbackProcessor
for _, processor := range c.processors {
if processor.name != "" {
switch processor.kind {
case "create":
creates = append(creates, processor)
case "update":
updates = append(updates, processor)
case "delete":
deletes = append(deletes, processor)
case "query":
queries = append(queries, processor)
case "row_query":
rowQueries = append(rowQueries, processor)
}
}
}
c.creates = sortProcessors(creates)
c.updates = sortProcessors(updates)
c.deletes = sortProcessors(deletes)
c.queries = sortProcessors(queries)
c.rowQueries = sortProcessors(rowQueries)
}