generate_models: add helpers to easily write sql columns and table aliases and joins

scripts/generate_db_helpers.go

@@ -257,6 +257,8 @@
 // This file contains constants for all db names involved in a mapped struct
 // It also add some accessors on the struct types so they implement a 'Mapped' interface
 
+import "github.com/Masterminds/squirrel"
+
 // Mapped is the common interface of all structs that are mapped in the database
 type Mapped interface {
 	Table() string
@@ -265,6 +267,45 @@
 	Values(columns ...string) []interface{}
 }
 
+type TableSchema interface {
+	GetName() string
+	Sql() string
+}
+
+type Column struct {
+	table TableSchema
+	name string
+}
+
+func (c Column) Sql() string {
+	return c.table.GetName()+"."+c.name
+}
+
+func (c Column) ToSql() (string, []interface{}, error ) {
+	return c.Sql(), nil, nil
+}
+
+func (c Column) Join(col Column) Join {
+	return Join{
+		from: c,
+		to: col,
+	}
+}
+
+func (c Column) Eq(value interface{}) squirrel.Eq{
+	return squirrel.Eq{c.Sql(): value}
+}
+
+type Join struct {
+	from Column
+	to Column
+}
+
+func (j Join) Sql() string {
+	return j.to.table.Sql() + " ON " + j.to.Sql() + " = " + j.from.Sql()
+}
+
+
 const (
 	// table and column names
 {{- range $i, $dbstruct := .DBStructs}}
@@ -378,4 +419,11 @@
 	}
 	return values
 }
+
+{{- if .HasTable}}
+
+func New{{.Name}}TableSchema() *{{.Name}}TableSchema {
+	t := {{.Name}}TableSchema{}
+{{- range .Fields}}
+	t.{{.Name}} = Column{&t, "{{.Column}}"}
 {{- end}}
@@ -381,3 +429,74 @@
 {{- end}}
+	return &t
+}
+
+type {{.Name}}TableSchema struct {
+	alias string
+
+{{- range .Fields}}
+	{{.Name}} Column
+{{- end}}
+}
+
+// Columns returns the database table column names
+func (t {{.Name}}TableSchema) Columns(withPKey bool) []string {
+	if withPKey {
+		return {{.Name}}Columns
+	}
+	return {{.Name}}DataColumns
+}
+
+func (t {{.Name}}TableSchema) As(name string) *{{.Name}}TableSchema {
+	t.alias = name
+{{- range .Fields}}
+	t.{{.Name}} = Column{&t, "{{.Column}}"}
+{{- end}}
+	return &t
+}
+
+func (t {{.Name}}TableSchema) GetName() string {
+	if t.alias == "" {
+		return {{.Name}}Table
+	}
+	return t.alias
+}
+
+func (t {{.Name}}TableSchema) Sql() string {
+	if t.alias == "" {
+		return {{.Name}}Table
+	}
+	return {{.Name}}Table + " AS " + t.alias
+}
+func (t {{.Name}}TableSchema) ToSql() (string, []interface{}, error) {
+	return t.Sql(), nil, nil
+}
+
+
+
+{{- end}}
+
+
+{{- end}}
+
+func NewDBSchema() *DBSchema {
+	return &DBSchema{
+{{- range $dbstruct := .DBStructs}}
+{{- if .HasTable}}
+		{{.Name}}: New{{.Name}}TableSchema(),
+{{- end}}
+{{- end}}
+	}
+}
+
+type DBSchema struct {
+{{- range $dbstruct := .DBStructs}}
+{{- if .HasTable}}
+	{{.Name}} *{{.Name}}TableSchema
+{{- end}}
+{{- end}}
+}
+
+var Schema = NewDBSchema()
+
 `))
 )