rest/rest.go

package rest

import (
	"context"
	"encoding/csv"
	"encoding/json"
	"fmt"
	"git.nspix.com/golang/micro/gateway/http"
	errpkg "git.nspix.com/golang/rest/v3/error"
	"git.nspix.com/golang/rest/v3/inflector"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
	httppkg "net/http"
	"path"
	"reflect"
	"strconv"
	"strings"
)

const (
	HttpAccessDenied          = 8004 //拒绝访问
	HttpInvalidPayload        = 8002 //请求内容无效
	HttpRequestCallbackFailed = 8003 //执行回调失败
	HttpValidateFailed        = 8008 //数据校验失败
	HttpDatabaseQueryFailed   = 8010 //查询失败
	HttpDatabaseFindFailed    = 8011 //查找失败
	HttpDatabaseCreateFailed  = 8012 //创建失败
	HttpDatabaseUpdateFailed  = 8013 //更新失败
	HttpDatabaseDeleteFailed  = 8014 //删除失败
	HttpDatabaseExportFailed  = 8015 //数据导出失败
	HTTPUnknownFailed         = 9001 //未知错误
)

const (
	ErrorAccessDeniedMessage = "access denied"
)

const (
	restCtxRequest  = "rest-ctx-request"
	restCtxResponse = "rest-ctx-response"
	restCtxHttpctx  = "rest-ctx-httpctx"
)

const (
	OperatorEqual        = "eq"
	OperatorGreaterThan  = "gt"
	OperatorGreaterEqual = "ge"
	OperatorLessThan     = "lt"
	OperatorLessEqual    = "le"
	OperatorLike         = "like"
	OperatorBetween      = "between"
)

type (
	DiffAttr struct {
		Column   string      `json:"column"`
		Label    string      `json:"label"`
		OldValue interface{} `json:"old_value"`
		NewValue interface{} `json:"new_value"`
	}

	Condition struct {
		Column string        `json:"column"`
		Expr   string        `json:"expr"`
		Value  interface{}   `json:"value,omitempty"`
		Values []interface{} `json:"values,omitempty"`
	}

	Restful struct {
		model         Model
		opts          *Options
		reflectType   reflect.Type
		reflectValue  reflect.Value
		singularName  string
		pluralizeName string
		statement     *gorm.Statement
		primaryKey    string
	}
)

// getScenarioUrl 获取某个场景下HTTP请求的URL
func (r *Restful) getScenarioUrl(scenario string) string {
	var uri string
	switch scenario {
	case ScenarioList:
		uri = r.opts.ApiPrefix + "/" + r.model.ModuleName() + "/" + r.pluralizeName
	case ScenarioView:
		uri = r.opts.ApiPrefix + "/" + r.model.ModuleName() + "/" + r.singularName + "/:id"
	case ScenarioCreate:
		uri = r.opts.ApiPrefix + "/" + r.model.ModuleName() + "/" + r.singularName
	case ScenarioUpdate:
		uri = r.opts.ApiPrefix + "/" + r.model.ModuleName() + "/" + r.singularName + "/:id"
	case ScenarioDelete:
		uri = r.opts.ApiPrefix + "/" + r.model.ModuleName() + "/" + r.singularName + "/:id"
	case ScenarioExport:
		uri = r.opts.ApiPrefix + "/" + r.model.ModuleName() + "/" + r.singularName + "-export"
	}
	return path.Clean(uri)
}

// getScenarioHandle 获取某个场景下HTTP请求的处理回调
func (r *Restful) getScenarioHandle(scenario string) http.HandleFunc {
	var handleFunc http.HandleFunc
	switch scenario {
	case ScenarioList:
		handleFunc = r.actionIndex
	case ScenarioView:
		handleFunc = r.actionView
	case ScenarioCreate:
		handleFunc = r.actionCreate
	case ScenarioUpdate:
		handleFunc = r.actionUpdate
	case ScenarioDelete:
		handleFunc = r.actionDelete
	case ScenarioExport:
		handleFunc = r.actionExport
	}
	return handleFunc
}

func (r *Restful) setFieldValue(model reflect.Value, column string, value interface{}) {
	var (
		name string
	)
	refVal := reflect.Indirect(model)
	for _, field := range r.statement.Schema.Fields {
		if field.DBName == column {
			name = field.Name
			break
		} else if field.Name == column {
			name = column
			break
		}
	}
	if name == "" {
		return
	}
	fieldVal := refVal.FieldByName(name)
	if fieldVal.CanSet() {
		fieldVal.Set(reflect.ValueOf(value))
	}
}

//getFieldValue get field value from reflect value
func (r *Restful) getFieldValue(model reflect.Value, column string) interface{} {
	var (
		name string
	)
	refVal := reflect.Indirect(model)
	for _, field := range r.statement.Schema.Fields {
		if field.DBName == column {
			name = field.Name
			break
		} else if field.Name == column {
			name = column
			break
		}
	}
	if name == "" {
		return nil
	}
	fieldVal := refVal.FieldByName(name)
	return fieldVal.Interface()
}

func (r *Restful) hasScenario(s string) bool {
	if v, ok := r.model.(FlexibleModel); ok {
		for _, n := range v.Scenarios() {
			if s == n {
				return true
			}
		}
		return false
	}
	return true
}

func (r *Restful) findCondition(schema *Schema, conditions []*Condition) *Condition {
	for _, cond := range conditions {
		if cond.Column == schema.Column {
			return cond
		}
	}
	return nil
}

func (r *Restful) prepareConditions(ctx context.Context, requestCtx *http.Context, query *Query, schemas []*Schema) (err error) {
	var (
		ok          bool
		skip        bool
		formValue   string
		model       interface{}
		activeModel ActiveModel
	)
	model = reflect.New(r.reflectType).Interface()
	if r.opts.Delegate != nil {
		if err = r.opts.Delegate.BeforeQuery(ctx, query); err != nil {
			return
		}
	}
	if activeModel, ok = model.(ActiveModel); ok {
		if err = activeModel.OnBeforeQuery(ctx, query); err != nil {
			return
		}
	}
	if requestCtx.Request().Method == httppkg.MethodPut || requestCtx.Request().Method == httppkg.MethodPost {
		conditions := make([]*Condition, 0)
		if err = requestCtx.Bind(&conditions); err != nil {
			return
		}
		for _, schema := range schemas {
			cond := r.findCondition(schema, conditions)
			if cond == nil {
				continue
			}
			switch schema.Format {
			case FormatInteger, FormatFloat, FormatTimestamp, FormatDatetime, FormatDate, FormatTime:
				switch cond.Expr {
				case OperatorBetween:
					if len(cond.Values) == 2 {
						query.AndFilterWhere(NewCond(schema.Column, cond.Values[0]).WithExpr(">="))
						query.AndFilterWhere(NewCond(schema.Column, cond.Values[1]).WithExpr("<="))
					}
				case OperatorGreaterThan:
					query.AndFilterWhere(NewCond(schema.Column, cond.Value).WithExpr(">"))
				case OperatorGreaterEqual:
					query.AndFilterWhere(NewCond(schema.Column, cond.Value).WithExpr(">="))
				case OperatorLessThan:
					query.AndFilterWhere(NewCond(schema.Column, cond.Value).WithExpr("<"))
				case OperatorLessEqual:
					query.AndFilterWhere(NewCond(schema.Column, cond.Value).WithExpr("<="))
				default:
					query.AndFilterWhere(NewCond(schema.Column, cond.Value))
				}
			default:
				switch cond.Expr {
				case OperatorLike:
					query.AndFilterWhere(NewCond(schema.Column, cond.Value).WithExpr("LIKE"))
				default:
					query.AndFilterWhere(NewCond(schema.Column, cond.Value))
				}
			}
		}
	} else {
		//处理默认的搜索
		for _, schema := range schemas {
			skip = false
			if skip {
				continue
			}
			if schema.Native == 0 {
				continue
			}
			formValue = requestCtx.FormValue(schema.Column)
			switch schema.Format {
			case FormatString, FormatText:
				if schema.Attribute.Match == MatchExactly {
					query.AndFilterWhere(NewCond(schema.Column, formValue))
				} else {
					query.AndFilterWhere(NewCond(schema.Column, formValue).WithExpr("LIKE"))
				}
			case FormatTime, FormatDate, FormatDatetime, FormatTimestamp:
				var sep string
				seps := []byte{',', '/'}
				for _, s := range seps {
					if strings.IndexByte(formValue, s) > -1 {
						sep = string(s)
					}
				}
				if ss := strings.Split(formValue, sep); len(ss) == 2 {
					query.AndFilterWhere(
						NewCond(schema.Column, strings.TrimSpace(ss[0])).WithExpr(">="),
						NewCond(schema.Column, strings.TrimSpace(ss[1])).WithExpr("<="),
					)
				} else {
					query.AndFilterWhere(NewCond(schema.Column, formValue))
				}
			case FormatInteger, FormatFloat:
				query.AndFilterWhere(NewCond(schema.Column, formValue))
			default:
				if schema.Type == TypeString {
					if schema.Attribute.Match == MatchExactly {
						query.AndFilterWhere(NewCond(schema.Column, formValue))
					} else {
						query.AndFilterWhere(NewCond(schema.Column, formValue).WithExpr("LIKE"))
					}
				} else {
					query.AndFilterWhere(NewCond(schema.Column, formValue))
				}
			}
		}
	}
	//处理排序
	sortPar := requestCtx.FormValue("sort")
	if sortPar != "" {
		sorts := strings.Split(sortPar, ",")
		for _, s := range sorts {
			if s[0] == '-' {
				query.OrderBy(s[1:], "DESC")
			} else {
				if s[0] == '+' {
					query.OrderBy(s[1:], "ASC")
				} else {
					query.OrderBy(s, "ASC")
				}
			}
		}
	}
	if activeModel, ok = model.(ActiveModel); ok {
		err = activeModel.OnAfterQuery(ctx, query)
	}
	if r.opts.Delegate != nil {
		err = r.opts.Delegate.AfterQuery(ctx, query)
	}
	return
}

func (r *Restful) createContext(httpCtx *http.Context) context.Context {
	ctx := httpCtx.Request().Context()
	if ctx == nil {
		ctx = context.Background()
	}
	ctx = context.WithValue(ctx, restCtxRequest, httpCtx.Request())
	ctx = context.WithValue(ctx, restCtxResponse, httpCtx.Response())
	ctx = context.WithValue(ctx, restCtxHttpctx, httpCtx)
	return ctx
}

func (r *Restful) actionIndex(httpCtx *http.Context) (err error) {
	var (
		page      int
		pageSize  int
		pageIndex int
		query     *Query
		namespace string
	)
	if !r.hasScenario(ScenarioList) {
		return httpCtx.Error(HttpAccessDenied, ErrorAccessDeniedMessage)
	}
	ctx := r.createContext(httpCtx)
	namespace = httpCtx.ParamValue(NamespaceVariable)
	page, _ = strconv.Atoi(httpCtx.FormValue("page"))
	pageSize, _ = strconv.Atoi(httpCtx.FormValue("pagesize"))
	if pageSize <= 0 {
		pageSize = 15
	}
	pageIndex = page
	if pageIndex > 0 {
		pageIndex--
	}
	sliceValue := reflect.MakeSlice(reflect.SliceOf(r.reflectType), 0, 0)
	models := reflect.New(sliceValue.Type())
	models.Elem().Set(sliceValue)
	query = NewQuery(r.opts.DB)
	searchSchemas := r.opts.LookupFunc(ctx, namespace, r.model.ModuleName(), r.model.TableName(), ScenarioSearch)
	indexSchemas := r.opts.LookupFunc(ctx, namespace, r.model.ModuleName(), r.model.TableName(), ScenarioList)
	if err = r.prepareConditions(ctx, httpCtx, query, searchSchemas); err != nil {
		return httpCtx.Error(HttpDatabaseQueryFailed, err.Error())
	}
	if r.opts.EnableNamespace {
		query.AndFilterWhere(NewQueryCondition(NamespaceField, namespace))
	}
	query.Offset(pageIndex * pageSize).Limit(pageSize)
	if err = query.All(models.Interface()); err != nil {
		return httpCtx.Error(HttpDatabaseQueryFailed, err.Error())
	}
	resp := &ListResponse{
		Page:       page,
		PageSize:   pageSize,
		TotalCount: query.Limit(0).Offset(0).Count(r.model),
	}
	if resp.TotalCount > 0 {
		resp.Data = r.opts.Formatter.formatModels(ctx, models.Interface(), indexSchemas, r.statement)
	} else {
		resp.Data = make([]string, 0)
	}
	return httpCtx.Success(resp)
}

func (r *Restful) actionCreate(httpCtx *http.Context) (err error) {
	var (
		errTx     error
		namespace string
		model     interface{}
		schemas   []*Schema
		refModel  reflect.Value
		diffAttrs []*DiffAttr
	)
	ctx := r.createContext(httpCtx)
	diffAttrs = make([]*DiffAttr, 0, 10)
	if !r.hasScenario(ScenarioCreate) {
		return httpCtx.Error(HttpAccessDenied, ErrorAccessDeniedMessage)
	}
	namespace = httpCtx.ParamValue(NamespaceVariable)
	refModel = reflect.New(r.reflectType)
	model = refModel.Interface()
	if err = httpCtx.Bind(model); err != nil {
		return httpCtx.Error(HttpInvalidPayload, err.Error())
	}
	schemas = r.opts.LookupFunc(ctx, namespace, r.model.ModuleName(), r.model.TableName(), ScenarioCreate)

	//global set field value
	r.setFieldValue(refModel, NamespaceField, namespace)
	r.setFieldValue(refModel, CreatedByField, httpCtx.ParamValue(UserVariable))
	r.setFieldValue(refModel, CreatedDeptField, httpCtx.ParamValue(DepartmentVariable))
	r.setFieldValue(refModel, UpdatedByField, httpCtx.ParamValue(UserVariable))
	r.setFieldValue(refModel, UpdatedDeptField, httpCtx.ParamValue(DepartmentVariable))

	if err = r.opts.DB.Transaction(func(tx *gorm.DB) error {
		if r.opts.Delegate != nil {
			if errTx = r.opts.Delegate.BeforeCreate(ctx, model); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, errTx.Error())
			}
			if errTx = r.opts.Delegate.BeforeSave(ctx, model); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, errTx.Error())
			}
		}
		if activeModel, ok := model.(ActiveModel); ok {
			if errTx = activeModel.OnBeforeCreate(ctx, model); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, errTx.Error())
			}
			if errTx = activeModel.OnBeforeSave(ctx, model); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, errTx.Error())
			}
		}
		//创建数据
		if errTx = tx.Create(model).Error; errTx != nil {
			return errTx
		}
		//对比差异数据
		for _, scm := range schemas {
			diffAttrs = append(diffAttrs, &DiffAttr{
				Column:   scm.Column,
				Label:    scm.Label,
				OldValue: nil,
				NewValue: r.getFieldValue(refModel, scm.Column),
			})
		}
		if activeModel, ok := model.(ActiveModel); ok {
			if errTx = activeModel.OnAfterCreate(ctx, model, diffAttrs); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, err.Error())
			}
			if errTx = activeModel.OnAfterSave(ctx, model, diffAttrs); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, err.Error())
			}
		}
		if r.opts.Delegate != nil {
			if errTx = r.opts.Delegate.AfterCreate(ctx, model, diffAttrs); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, err.Error())
			}
			if errTx = r.opts.Delegate.AfterSave(ctx, model, diffAttrs); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, err.Error())
			}
		}
		return errTx
	}); err == nil {
		pkVal := r.getFieldValue(refModel, r.primaryKey)
		return httpCtx.Success(&CreateResponse{
			ID:    pkVal,
			Topic: r.model.TableName(),
			State: "created",
		})
	}
	//form validation
	if validateError, ok := err.(*errpkg.StructError); ok {
		httpCtx.Response().Header().Set("Content-Type", "application/json")
		return json.NewEncoder(httpCtx.Response()).Encode(map[string]interface{}{
			"errno":  HttpValidateFailed,
			"result": validateError,
		})
	}
	return httpCtx.Error(HttpDatabaseCreateFailed, err.Error())
}

func (r *Restful) actionUpdate(httpCtx *http.Context) (err error) {
	var (
		errTx     error
		namespace string
		model     interface{}
		schemas   []*Schema
		refModel  reflect.Value
		oldValues = make(map[string]interface{})
		diffs     = make(map[string]interface{})
		diffAttrs = make([]*DiffAttr, 0)
	)
	ctx := r.createContext(httpCtx)
	if !r.hasScenario(ScenarioUpdate) {
		return httpCtx.Error(HttpAccessDenied, ErrorAccessDeniedMessage)
	}
	namespace = httpCtx.ParamValue(NamespaceVariable)
	idStr := httpCtx.ParamValue("id")
	refModel = reflect.New(r.reflectType)
	model = refModel.Interface()
	//默认设置更新用户
	r.setFieldValue(refModel, UpdatedByField, httpCtx.ParamValue(UserVariable))
	r.setFieldValue(refModel, UpdatedDeptField, httpCtx.ParamValue(DepartmentVariable))
	conditions := map[string]interface{}{
		r.primaryKey: idStr,
	}
	if r.opts.EnableNamespace {
		conditions[NamespaceField] = namespace
	}
	if err = r.opts.DB.Where(conditions).First(model).Error; err != nil {
		return httpCtx.Error(HttpDatabaseFindFailed, err.Error())
	}
	schemas = r.opts.LookupFunc(ctx, namespace, r.model.ModuleName(), r.model.TableName(), ScenarioUpdate)
	for _, scm := range schemas {
		oldValues[scm.Column] = r.getFieldValue(refModel, scm.Column)
	}
	if err = httpCtx.Bind(model); err != nil {
		return httpCtx.Error(HttpInvalidPayload, err.Error())
	}
	if err = r.opts.DB.Transaction(func(tx *gorm.DB) error {
		if r.opts.Delegate != nil {
			if errTx = r.opts.Delegate.BeforeUpdate(ctx, model); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, errTx.Error())
			}
			if errTx = r.opts.Delegate.BeforeSave(ctx, model); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, errTx.Error())
			}
		}
		if activeModel, ok := model.(ActiveModel); ok {
			if errTx = activeModel.OnBeforeUpdate(ctx, model); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, errTx.Error())
			}
			if errTx = activeModel.OnBeforeSave(ctx, model); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, errTx.Error())
			}
		}
		//对比差异数据
		for _, scm := range schemas {
			v := r.getFieldValue(refModel, scm.Column)
			if oldValues[scm.Column] != v {
				diffs[scm.Column] = v
				diffAttrs = append(diffAttrs, &DiffAttr{
					Column:   scm.Column,
					Label:    scm.Label,
					OldValue: oldValues[scm.Column],
					NewValue: v,
				})
			}
		}
		//进行局部数据更新
		if len(diffs) > 0 {
			if errTx = tx.Model(model).Updates(diffs).Error; errTx != nil {
				return errTx
			}
		}
		if activeModel, ok := model.(ActiveModel); ok {
			if errTx = activeModel.OnAfterUpdate(ctx, model, diffAttrs); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, errTx.Error())
			}
			if errTx = activeModel.OnAfterSave(ctx, model, diffAttrs); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, errTx.Error())
			}
		}
		if r.opts.Delegate != nil {
			if errTx = r.opts.Delegate.AfterUpdate(ctx, model, diffAttrs); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, errTx.Error())
			}
			if errTx = r.opts.Delegate.AfterSave(ctx, model, diffAttrs); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, errTx.Error())
			}
		}
		return errTx
	}); err == nil {
		pkVal := r.getFieldValue(refModel, r.primaryKey)
		return httpCtx.Success(&UpdateResponse{
			ID:    pkVal,
			Topic: r.model.TableName(),
			State: "updated",
		})
	}
	//form validation
	if validateError, ok := err.(*errpkg.StructError); ok {
		httpCtx.Response().Header().Set("Content-Type", "application/json")
		return json.NewEncoder(httpCtx.Response()).Encode(map[string]interface{}{
			"errno":  HttpValidateFailed,
			"result": validateError,
		})
	}
	return httpCtx.Error(HttpDatabaseUpdateFailed, err.Error())
}

func (r *Restful) actionDelete(httpCtx *http.Context) (err error) {
	var (
		errTx     error
		model     interface{}
		namespace string
	)
	if !r.hasScenario(ScenarioDelete) {
		return httpCtx.Error(HttpAccessDenied, ErrorAccessDeniedMessage)
	}
	ctx := r.createContext(httpCtx)
	idStr := httpCtx.ParamValue("id")
	namespace = httpCtx.ParamValue(NamespaceVariable)
	model = reflect.New(r.reflectType).Interface()
	conditions := map[string]interface{}{
		r.primaryKey: idStr,
	}
	if r.opts.EnableNamespace {
		conditions[NamespaceField] = namespace
	}
	if err = r.opts.DB.Where(conditions).First(model).Error; err != nil {
		return httpCtx.Error(HttpDatabaseFindFailed, err.Error())
	}
	if err = r.opts.DB.Transaction(func(tx *gorm.DB) error {
		if r.opts.Delegate != nil {
			if errTx = r.opts.Delegate.BeforeDelete(ctx, model); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, errTx.Error())
			}
		}
		if activeModel, ok := model.(ActiveModel); ok {
			if errTx = activeModel.OnBeforeDelete(ctx, model); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, errTx.Error())
			}
		}
		if errTx = tx.Delete(model).Error; errTx != nil {
			return errTx
		}
		if activeModel, ok := model.(ActiveModel); ok {
			if errTx = activeModel.OnAfterDelete(ctx, model); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, errTx.Error())
			}
		}
		if r.opts.Delegate != nil {
			if errTx = r.opts.Delegate.AfterDelete(ctx, model); errTx != nil {
				return httpCtx.Error(HttpRequestCallbackFailed, errTx.Error())
			}
		}
		return errTx
	}); err == nil {
		return httpCtx.Success(&DeleteResponse{
			ID:    r.getFieldValue(reflect.ValueOf(model), r.primaryKey),
			Topic: r.model.TableName(),
			State: "updated",
		})
	} else {
		return httpCtx.Error(HttpDatabaseDeleteFailed, err.Error())
	}
}

func (r *Restful) actionExport(httpCtx *http.Context) (err error) {
	var (
		query     *Query
		namespace string
	)
	if !r.hasScenario(ScenarioExport) {
		return httpCtx.Error(HttpAccessDenied, ErrorAccessDeniedMessage)
	}
	ctx := r.createContext(httpCtx)
	namespace = httpCtx.ParamValue(NamespaceVariable)
	sliceValue := reflect.MakeSlice(reflect.SliceOf(r.reflectType), 0, 0)
	models := reflect.New(sliceValue.Type())
	models.Elem().Set(sliceValue)
	query = NewQuery(r.opts.DB)
	searchSchemas := r.opts.LookupFunc(ctx, namespace, r.model.ModuleName(), r.model.TableName(), ScenarioSearch)
	exportSchemas := r.opts.LookupFunc(ctx, namespace, r.model.ModuleName(), r.model.TableName(), ScenarioList)
	if err = r.prepareConditions(ctx, httpCtx, query, searchSchemas); err != nil {
		return httpCtx.Error(HttpDatabaseQueryFailed, err.Error())
	}
	if r.opts.EnableNamespace {
		query.AndFilterWhere(NewQueryCondition(NamespaceVariable, namespace))
	}
	if err = query.All(models.Interface()); err != nil {
		return httpCtx.Error(HttpDatabaseExportFailed, err.Error())
	}
	httpCtx.Response().Header().Set("Content-Type", "text/csv")
	httpCtx.Response().Header().Set("Access-Control-Expose-Headers", "Content-Disposition")
	httpCtx.Response().Header().Set("Content-Disposition", fmt.Sprintf("attachment;filename=%s.csv", r.singularName))
	value := r.opts.Formatter.formatModels(ctx, models.Interface(), exportSchemas, r.statement)
	writer := csv.NewWriter(httpCtx.Response())
	ss := make([]string, len(exportSchemas))
	for i, field := range exportSchemas {
		ss[i] = field.Label
	}
	_ = writer.Write(ss)
	if values, ok := value.([]interface{}); ok {
		for _, val := range values {
			row, ok2 := val.(map[string]interface{})
			if !ok2 {
				continue
			}
			for i, field := range exportSchemas {
				if v, ok := row[field.Column]; ok {
					ss[i] = fmt.Sprint(v)
				} else {
					ss[i] = ""
				}
			}
			_ = writer.Write(ss)
		}
	}
	writer.Flush()
	return
}

func (r *Restful) actionView(httpCtx *http.Context) (err error) {
	var (
		model     interface{}
		namespace string
	)
	if !r.hasScenario(ScenarioView) {
		return httpCtx.Error(HttpAccessDenied, ErrorAccessDeniedMessage)
	}
	ctx := r.createContext(httpCtx)
	namespace = httpCtx.ParamValue(NamespaceVariable)
	scenario := httpCtx.FormValue("scenario")
	idStr := httpCtx.ParamValue("id")
	model = reflect.New(r.reflectType).Interface()
	conditions := map[string]interface{}{
		r.primaryKey: idStr,
	}
	if r.opts.EnableNamespace {
		conditions[NamespaceField] = namespace
	}
	if err = r.opts.DB.Where(conditions).First(model).Error; err != nil {
		return httpCtx.Error(HttpDatabaseFindFailed, err.Error())
	}
	if httpCtx.FormValue("format") != "" {
		//获取指定场景下面的字段进行渲染显示
		var schemas []*Schema
		if scenario == "" {
			schemas = r.opts.LookupFunc(ctx, namespace, r.model.ModuleName(), r.model.TableName(), ScenarioView)
		} else {
			schemas = r.opts.LookupFunc(ctx, namespace, r.model.ModuleName(), r.model.TableName(), scenario)
		}
		return httpCtx.Success(r.opts.Formatter.formatModel(ctx, model, schemas, r.statement))
	}
	return httpCtx.Success(model)
}

func newRestful(model Model, opts *Options) *Restful {
	var (
		ok           bool
		err          error
		tableName    string
		dynamicModel *Dynamic
	)
	r := &Restful{
		opts:  opts,
		model: model,
	}
	if dynamicModel, ok = model.(*Dynamic); ok {
		r.reflectValue = reflect.New(dynamicModel.Type()).Elem()
		r.reflectType = dynamicModel.Type()
	} else {
		r.reflectValue = reflect.Indirect(reflect.ValueOf(model))
		r.reflectType = r.reflectValue.Type()
	}
	tableName = model.TableName()
	r.singularName = inflector.Singularize(tableName)
	r.pluralizeName = inflector.Pluralize(tableName)

	r.statement = &gorm.Statement{
		DB:       r.opts.DB,
		ConnPool: r.opts.DB.ConnPool,
		Clauses:  map[string]clause.Clause{},
	}
	if dynamicModel, ok = model.(*Dynamic); ok {
		err = r.statement.Parse(dynamicModel.Interface())
	} else {
		err = r.statement.Parse(model)
	}
	if err == nil {
		if r.statement.Schema != nil {
			if r.statement.Schema.PrimaryFieldDBNames != nil && len(r.statement.Schema.PrimaryFieldDBNames) > 0 {
				r.primaryKey = r.statement.Schema.PrimaryFieldDBNames[0]
			}
		}
	}
	return r
}