基于Vue和Quasar的前端SPA项目实战之数据库逆向（十二）
回顾
通过之前文章 基于Vue和Quasar的前端SPA项目实战之动态表单（五）的介绍，实现了动态表单功能。如果是全新的项目，通过配置元数据并且创建物理表，从而自动实现业务数据的CRUD增删改查。但是如果数据库表已经存在的情况下，如何通过配置表单元数据进行管理呢？这时候数据库逆向功能就很有必要了。
简介
数据库逆向就是通过读取数据库物理表schema信息，然后生成表单元数据，可以看成“dbfirst”模式，即先有数据库表，然后根据表生成元数据，逆向表单后续操作和普通动态表单类似。
UI界面
输入物理表名称，启用“数据库逆向”功能，然后点击“加载元数据”，然后会自动填充表单字段相关元数据信息。
数据表准备
以ca_product产品为例，通过phpmyadmin创建表
创建产品表
CREATE TABLE `ca_product` ( `id` bigint UNSIGNED NOT NULL COMMENT '编号', `name` varchar(200) COLLATE utf8mb4_unicode_ci NOT NULL COMMENT '名称', `fullTextBody` text COLLATE utf8mb4_unicode_ci COMMENT '全文索引', `createdDate` datetime NOT NULL COMMENT '创建时间', `lastModifiedDate` datetime DEFAULT NULL COMMENT '修改时间', `code` varchar(200) COLLATE utf8mb4_unicode_ci DEFAULT NULL COMMENT '编码', `brand` varchar(200) COLLATE utf8mb4_unicode_ci DEFAULT NULL COMMENT '品牌', `price` decimal(10,) DEFAULT NULL COMMENT '单价', `weight` decimal(10,) DEFAULT NULL COMMENT '重量', `length` decimal(10,) DEFAULT NULL COMMENT '长', `width` decimal(10,) DEFAULT NULL COMMENT '宽', `high` decimal(10,) DEFAULT NULL COMMENT '高', `ats` bigint DEFAULT NULL COMMENT '库存个数') ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci COMMENT='产品';
ALTER TABLE `ca_product` ADD PRIMARY KEY (`id`), ADD UNIQUE KEY `UQ_CODE` (`code`) USING BTREE;ALTER TABLE `ca_product` ADD FULLTEXT KEY `ft_fulltext_body` (`fullTextBody`);
ALTER TABLE `ca_product` MODIFY `id` bigint UNSIGNED NOT NULL AUTO_INCREMENT COMMENT '编号', AUTO_INCREMENT=1;COMMIT;
查询schema
mysql数据库通过如下SQL语句可以查询表单、字段、索引等信息
SHOW TABLE STATUS LIKE TABLE_NAMESHOW FULL COLUMNS FROM TABLE_NAMESHOW INDEX FROM TABLE_NAME
表基本信息
字段信息
索引信息
API JSON
通过API /api/metadata/tables/metadata/ca_product查询ca_product的schema信息, 格式如下：
{ "Name": "ca_product", "Engine": "InnoDB", "Version": 10, "Row_format": "Dynamic", "Rows": , "Avg_row_length": , "Data_length": 16384, "Max_data_length": , "Index_length": 32768, "Data_free": , "Auto_increment": 2, "Create_time": 1628141282000, "Update_time": 1628141304000, "Collation": "utf8mb4_unicode_ci", "Create_options": "", "Comment": "产品", "columns": [{ "Field": "id", "Type": "bigint unsigned", "Null": "NO", "Key": "PRI", "Extra": "auto_increment", "Privileges": "select,insert,update,references", "Comment": "编号" }, { "Field": "name", "Type": "varchar(200)", "Collation": "utf8mb4_unicode_ci", "Null": "NO", "Key": "", "Extra": "", "Privileges": "select,insert,update,references", "Comment": "名称" }, { "Field": "fullTextBody", "Type": "text", "Collation": "utf8mb4_unicode_ci", "Null": "YES", "Key": "MUL", "Extra": "", "Privileges": "select,insert,update,references", "Comment": "全文索引" }, { "Field": "createdDate", "Type": "datetime", "Null": "NO", "Key": "", "Extra": "", "Privileges": "select,insert,update,references", "Comment": "创建时间" }, { "Field": "lastModifiedDate", "Type": "datetime", "Null": "YES", "Key": "", "Extra": "", "Privileges": "select,insert,update,references", "Comment": "修改时间" }, { "Field": "code", "Type": "varchar(200)", "Collation": "utf8mb4_unicode_ci", "Null": "YES", "Key": "UNI", "Extra": "", "Privileges": "select,insert,update,references", "Comment": "编码" }, { "Field": "brand", "Type": "varchar(200)", "Collation": "utf8mb4_unicode_ci", "Null": "YES", "Key": "", "Extra": "", "Privileges": "select,insert,update,references", "Comment": "品牌" }, { "Field": "price", "Type": "decimal(10,0)", "Null": "YES", "Key": "", "Extra": "", "Privileges": "select,insert,update,references", "Comment": "单价" }, { "Field": "weight", "Type": "decimal(10,0)", "Null": "YES", "Key": "", "Extra": "", "Privileges": "select,insert,update,references", "Comment": "重量" }, { "Field": "length", "Type": "decimal(10,0)", "Null": "YES", "Key": "", "Extra": "", "Privileges": "select,insert,update,references", "Comment": "长" }, { "Field": "width", "Type": "decimal(10,0)", "Null": "YES", "Key": "", "Extra": "", "Privileges": "select,insert,update,references", "Comment": "宽" }, { "Field": "high", "Type": "decimal(10,0)", "Null": "YES", "Key": "", "Extra": "", "Privileges": "select,insert,update,references", "Comment": "高" }, { "Field": "ats", "Type": "bigint", "Null": "YES", "Key": "", "Extra": "", "Privileges": "select,insert,update,references", "Comment": "库存个数" }], "indexs": [{ "Table": "ca_product", "Non_unique": , "Key_name": "PRIMARY", "Seq_in_index": 1, "Column_name": "id", "Collation": "A", "Cardinality": , "Null": "", "Index_type": "BTREE", "Comment": "", "Index_comment": "", "Visible": "YES" }, { "Table": "ca_product", "Non_unique": , "Key_name": "UQ_CODE", "Seq_in_index": 1, "Column_name": "code", "Collation": "A", "Cardinality": , "Null": "YES", "Index_type": "BTREE", "Comment": "", "Index_comment": "", "Visible": "YES" }, { "Table": "ca_product", "Non_unique": 1, "Key_name": "ft_fulltext_body", "Seq_in_index": 1, "Column_name": "fullTextBody", "Cardinality": , "Null": "YES", "Index_type": "FULLTEXT", "Comment": "", "Index_comment": "", "Visible": "YES" }]}核心代码
前端根据API返回的schema信息，转换成crudapi的元数据格式，并显示在UI上, 主要代码在文件metadata/table/new.vue中，通过addRowFromMetadata方法添加字段，addIndexFromMetadata添加联合索引。
addRowFromMetadata(id, t, singleIndexColumns) { const columns = this.table.columns; const index = columns.length + 1; const type = t.Type.toUpperCase(); const name = t.Field;
let length = null; let precision = null; let scale = null;
let typeArr = type.split("("); if (typeArr.length > 1) { const lengthOrprecisionScale = typeArr[1].split(")")[]; if (lengthOrprecisionScale.indexOf(",") > ) { precision = lengthOrprecisionScale.split(",")[]; scale = lengthOrprecisionScale.split(",")[1]; } else { length = lengthOrprecisionScale; } }
let indexType = null; let indexStorage = null; let indexName = null; let indexColumn = singleIndexColumns[name]; if (indexColumn) { if (indexColumn.Key_name === "PRIMARY") { indexType = "PRIMARY"; } else if (indexColumn.Index_type === "FULLTEXT") { indexType = "FULLTEXT"; indexName = indexColumn.Key_name; } else if (indexColumn.Non_unique === ) { indexType = "UNIQUE"; indexName = indexColumn.Key_name; indexStorage = indexColumn.Index_type; } else { indexType = "INDEX"; indexName = indexColumn.Key_name; indexStorage = indexColumn.Index_type; } } const comment = t.Comment ? t.Comment : name;
const newRow = { id: id, autoIncrement: (t.Extra === "auto_increment"), displayOrder: columns.length, insertable: true, nullable: (t.Null === "YES"), queryable: true, displayable: false, unsigned: type.indexOf("UNSIGNED") >= , updatable: true, dataType : typeArr[].replace("UNSIGNED", "").trim(), indexType: indexType, indexStorage: indexStorage, indexName: indexName, name: name, caption: comment, description: comment, length: length, precision: precision, scale: scale, systemable: false }; this.table.columns = [ ...columns.slice(, index), newRow, ...columns.slice(index) ];},
addIndexFromMetadata(union) { let baseId = (new Date()).valueOf();
let newIndexs = []; const tableColumns = this.table.columns; console.dir(tableColumns);
for (let key in union) { const unionLines = union[key]; const newIndexLines = [];
unionLines.forEach((item) => { const columnName = item.Column_name; const columnId = tableColumns.find(t => t.name === columnName).id;
newIndexLines.push({ column: { id: columnId, name: columnName } }); });
const unionLineFirst = unionLines[]; let indexType = null; let indexStorage = null; if (unionLineFirst.Key_name === "PRIMARY") { indexType = "PRIMARY"; } else if (unionLineFirst.Non_unique === ) { indexType = "UNIQUE"; indexStorage = unionLineFirst.Index_type; } else { indexType = "INDEX"; indexStorage = unionLineFirst.Index_type; }
const indexComment = unionLineFirst.Index_comment ? unionLineFirst.Index_comment: unionLineFirst.Key_name;
const newIndex = { id: baseId++, isNewRow: true, caption: indexComment, description: indexComment, indexStorage: indexStorage, indexType: indexType, name: unionLineFirst.Key_name, indexLines: newIndexLines }
newIndexs.push(newIndex); }
this.table.indexs = newIndexs; if (this.table.indexs) { this.indexCount = this.table.indexs.length; } else { this.indexCount = ; }}例子
以ca_product为例子, 点击“加载元数据之后”，表字段和索引都正确的显示了。保存成功之后，已经存在的物理表ca_product会自动被元数据管理起来，后续可以通过crudapi后台继续编辑，通过数据库逆向功能，零代码实现了物理表ca_product的CRUD增删改查功能。
小结
本文主要介绍了数据库逆向功能，在数据库表单已经存在的基础上，通过数据库逆向功能，快速生成元数据，不需要一行代码，我们就可以得到已有数据库的基本crud功能，包括API和UI。类似于phpmyadmin等数据库UI管理系统，但是比数据库UI管理系统更灵活，更友好。目前数据库逆向一次只支持一个表，如果同时存在很多物理表，就需要批量操作了。后续会继续优化，实现批量数据库逆向功能。
来自：https://mp.weixin.qq.com/s/dOeLCnIAq4YHTm5-8OrZJQ
