feat: add cache method to store columnName (#43)

* feat: add cache method to store columnName

* ci: add license

Author: afumu

gplus/cache.go

@@ -0,0 +1,99 @@
+/*
+ * Licensed to the AcmeStack under one or more contributor license
+ * agreements. See the NOTICE file distributed with this work for
+ * additional information regarding copyright ownership.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package gplus
+
+import (
+	"gorm.io/gorm/schema"
+	"reflect"
+	"sync"
+)
+
+// 缓存项目中所有实体字段名，储存格式：key为字段指针值，value为字段名
+// 通过缓存实体的字段名，方便gplus通过字段指针获取到对应的字段名
+var columnNameCache sync.Map
+
+// 缓存实体对象，主要给NewQuery方法返回使用
+var modelInstanceCache sync.Map
+
+// Cache 缓存实体对象所有的字段名
+func Cache(model any, namingStrategy ...schema.Namer) {
+	valueOf := reflect.ValueOf(model).Elem()
+	typeOf := reflect.TypeOf(model).Elem()
+
+	for i := 0; i < valueOf.NumField(); i++ {
+		field := typeOf.Field(i)
+		// 如果当前实体嵌入了其他实体，同样需要缓存它的字段名
+		if field.Anonymous {
+			// 如果存在多重嵌套，通过递归方式获取他们的字段名
+			subFieldMap := getSubFieldColumnNameMap(valueOf, field)
+			for key, value := range subFieldMap {
+				columnNameCache.Store(key, value)
+			}
+		} else {
+			// 获取对象字段指针值
+			pointer := valueOf.Field(i).Addr().Pointer()
+			name := parseColumnName(field, namingStrategy...)
+			columnNameCache.Store(pointer, name)
+		}
+	}
+
+	// 缓存对象
+	modelTypeStr := reflect.TypeOf(model).Elem().String()
+	modelInstanceCache.Store(modelTypeStr, model)
+}
+
+// 递归获取嵌套字段名
+func getSubFieldColumnNameMap(valueOf reflect.Value, field reflect.StructField) map[uintptr]string {
+	result := make(map[uintptr]string)
+
+	modelType := field.Type
+	if modelType.Kind() == reflect.Ptr {
+		modelType = modelType.Elem()
+	}
+	for j := 0; j < modelType.NumField(); j++ {
+		subField := modelType.Field(j)
+		if subField.Anonymous {
+			nestedFields := getSubFieldColumnNameMap(valueOf, subField)
+			for key, value := range nestedFields {
+				result[key] = value
+			}
+		} else {
+			pointer := valueOf.FieldByName(modelType.Field(j).Name).Addr().Pointer()
+			name := parseColumnName(modelType.Field(j))
+			result[pointer] = name
+		}
+	}
+
+	return result
+}
+
+// 获取字段名称
+func parseColumnName(field reflect.StructField, namingStrategy ...schema.Namer) string {
+	tagSetting := schema.ParseTagSetting(field.Tag.Get("gorm"), ";")
+	name, ok := tagSetting["COLUMN"]
+	if ok {
+		return name
+	}
+
+	if len(namingStrategy) > 0 {
+		return namingStrategy[0].ColumnName("", field.Name)
+	}
+
+	strategy := schema.NamingStrategy{}
+	return strategy.ColumnName("", field.Name)
+}