fix🐛: generate a model and DTOs for any single-column primary key

The model and DTO templates assumed every table's key is an int column named
id. For any other key the generated backend did not compile - the model
embedded models.Model, which supplies Id, skipped the real key column, and
GetId then returned a field that did not exist ("e.Code undefined"). Past the
compile error there was more of the same assumption:

  - GetReq and UpdateReq bound the key with uri:"<json field>", while every
    generated router registers it as :id, so any other name bound nothing;
  - InsertReq tagged the key json:"-", so a key the database does not assign,
    such as a string, could never be supplied;
  - DeleteReq took Ids []int, so a string key could not be deleted.

models.Model now stands in for the key only when the key is exactly an int
named Id; anything else is declared as its own primaryKey field. The key is
bound from :id, accepted from the request body when it is not an int, and
deleted by a list of its own type. A table keyed on an int id renders
byte-for-byte as before.

template/v4/dto.go.template

@@ -1,6 +1,13 @@
 package dto
 
 import (
+    {{- /*
+      $embed: the key is models.Model's own Id, so the model embeds it.
+      $pkType: the key's Go type, for the delete request's id list.
+    */ -}}
+    {{- $embed := false -}}
+    {{- $pkType := "int" -}}
+    {{- range .Columns -}}{{- if .Pk -}}{{- $pkType = .GoType -}}{{- if and (eq .GoField "Id") (eq .GoType "int") -}}{{- $embed = true -}}{{- end -}}{{- end -}}{{- end -}}
     {{- $bb := false -}}
     {{- range .Columns -}}
     {{- $z := .IsQuery -}}
@@ -52,7 +59,7 @@ type {{.ClassName}}InsertReq struct {
     {{- range .Columns -}}
     {{$x := .Pk}}
     {{- if ($x) }}
-    {{.GoField}} {{.GoType}} `json:"-" comment:"{{.ColumnComment}}"` // {{.ColumnComment}}
+    {{.GoField}} {{.GoType}} `json:"{{if eq .GoType "int"}}-{{else}}{{.JsonField}}{{end}}" comment:"{{.ColumnComment}}"` // {{.ColumnComment}}
     {{- else if eq .GoField "CreatedAt" -}}
     {{- else if eq .GoField "UpdatedAt" -}}
     {{- else if eq .GoField "DeletedAt" -}}
@@ -69,9 +76,13 @@ func (s *{{.ClassName}}InsertReq) Generate(model *models.{{.ClassName}})  {
 	 {{- range .Columns -}}
     {{$x := .Pk}}
     {{- if ($x) }}
+    {{- if $embed }}
     if s.{{.GoField}} == 0 {
         model.Model = common.Model{ {{.GoField}}: s.{{.GoField}} }
     }
+    {{- else }}
+    model.{{.GoField}} = s.{{.GoField}}
+    {{- end }}
     {{- else if eq .GoField "CreatedAt" -}}
     {{- else if eq .GoField "UpdatedAt" -}}
     {{- else if eq .GoField "DeletedAt" -}}
@@ -92,7 +103,7 @@ type {{.ClassName}}UpdateReq struct {
     {{- range .Columns -}}
     {{$x := .Pk}}
     {{- if ($x) }}
-    {{.GoField}} {{.GoType}} `uri:"{{.JsonField}}" comment:"{{.ColumnComment}}"` // {{.ColumnComment}}
+    {{.GoField}} {{.GoType}} `uri:"id" comment:"{{.ColumnComment}}"` // {{.ColumnComment}}
     {{- else if eq .GoField "CreatedAt" -}}
     {{- else if eq .GoField "UpdatedAt" -}}
     {{- else if eq .GoField "DeletedAt" -}}
@@ -109,9 +120,11 @@ func (s *{{.ClassName}}UpdateReq) Generate(model *models.{{.ClassName}})  {
 	 {{- range .Columns -}}
     {{$x := .Pk}}
     {{- if ($x) }}
+    {{- if $embed }}
     if s.{{.GoField}} == 0 {
         model.Model = common.Model{ {{.GoField}}: s.{{.GoField}} }
     }
+    {{- end }}
     {{- else if eq .GoField "CreatedAt" -}}
     {{- else if eq .GoField "UpdatedAt" -}}
     {{- else if eq .GoField "DeletedAt" -}}
@@ -133,7 +146,7 @@ type {{.ClassName}}GetReq struct {
 	{{- range .Columns -}}
     {{$x := .Pk}}
     {{- if ($x) }}
-     {{.GoField}} {{.GoType}} `uri:"{{.JsonField}}"`
+     {{.GoField}} {{.GoType}} `uri:"id"`
     {{- end }}
     {{- end }}
 }
@@ -143,7 +156,7 @@ func (s *{{.ClassName}}GetReq) GetId() interface{} {
 
 // {{.ClassName}}DeleteReq 功能删除请求参数
 type {{.ClassName}}DeleteReq struct {
-	Ids []int `json:"ids"`
+	Ids []{{$pkType}} `json:"ids"`
 }
 
 func (s *{{.ClassName}}DeleteReq) GetId() interface{} {

template/v4/model.go.template

@@ -24,11 +24,24 @@ import (
 
 )
 
+{{/*
+  models.Model supplies an int primary key named Id, so it stands in for the
+  key column only when that is exactly the key the table has. Any other key -
+  a different name, or a string - is declared as its own field, or GetId below
+  would name a field that does not exist.
+*/ -}}
+{{- $embed := false -}}
+{{- range .Columns -}}{{- if and .Pk (eq .GoField "Id") (eq .GoType "int") -}}{{- $embed = true -}}{{- end -}}{{- end -}}
 type {{.ClassName}} struct {
+    {{- if $embed }}
     models.Model
+    {{- end }}
     {{ range .Columns -}}
     {{$x := .Pk}}
     {{- if ($x) }}
+    {{- if not $embed }}
+    {{.GoField}} {{.GoType}} `json:"{{.JsonField}}" gorm:"primaryKey;type:{{.ColumnType}};comment:{{- if eq .ColumnComment "" -}}{{.GoField}}{{- else -}}{{.ColumnComment}}{{end -}}"`
+    {{- end }}
     {{- else if eq .GoField "CreatedAt" -}}
     {{- else if eq .GoField "UpdatedAt" -}}
     {{- else if eq .GoField "DeletedAt" -}}