fix: recognize json_valid constraint as json field type for database mariadb #2746

[oldme-git]

fixed #2746

Dear reviewer:
修复 mariaDb gf gen dao 的 json 字段识别为 string 问题

实现说明

在 mysql driver 中增加对 mariaDb 的识别，如果是，则使用 mariaDb 特有的 json 字段类型的判断方式，用以和 mysql json 做出区分

[oldme-git]

@gqcn First, please upload loads/mariadb:10.4

[houseme]

fixed #2746

Dear reviewer: 修复 mariaDb gf gen dao 的 json 字段识别为 string 问题

实现说明

在 mysql driver 中增加对 mariaDb 的识别，如果是，则使用 mariaDb 特有的 json 字段类型的判断方式，用以和 mysql json 做出区分

MariaDB 中json字段存的就是longtext类型，不是json

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fixed #2746

Dear reviewer: Fix the problem that the json field of mariaDb gf gen dao is recognized as string

Implementation instructions

Add recognition of mariaDb in mysql driver. If yes, use mariaDb’s unique json field type judgment method to distinguish it from mysql json

The json field in MariaDB stores the longtext type, not json

[oldme-git]

fixed #2746
Dear reviewer: 修复 mariaDb gf gen dao 的 json 字段识别为 string 问题

实现说明

在 mysql driver 中增加对 mariaDb 的识别，如果是，则使用 mariaDb 特有的 json 字段类型的判断方式，用以和 mysql json 做出区分

MariaDB 中json字段存的就是longtext类型，不是json

MariaDB 存 json 字段的确时 longtext，但是会在其上加上 json 约束：https://mariadb.com/resources/blog/using-json-in-mariadb/

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fixed #2746
Dear reviewer: Fixed the problem that the json field of mariaDb gf gen dao is recognized as string

Implementation instructions

Add recognition of mariaDb in mysql driver, If so, use mariaDb's unique json field type judgment method to distinguish it from mysql json

The json field in MariaDB stores the longtext type, not json

MariaDB does store json fields as longtext, but will add json constraints to it: https://mariadb.com/resources/blog/using-json-in-mariadb/

[houseme]

CREATE TABLE locations (
    id INT NOT NULL AUTO_INCREMENT,
    name VARCHAR(100) NOT NULL,  
    type CHAR(1) NOT NULL,
    latitude DECIMAL(9,6) NOT NULL,
    longitude DECIMAL(9,6) NOT NULL,
    attr LONGTEXT CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL 
    CHECK (JSON_VALID(`attr`)
     PRIMARY KEY (id)
);

请注意， attr 列的数据类型是 LONGTEXT 。除此之外，您会发现字符集和排序规则字段中添加了一些约束。然而，最重要的是 CHECK 约束，它指示当 attr 中的数据通过插入或更新进行修改时将执行的函数。
JSON_VALID() 函数是一个预定义函数，用于接收 JSON 数据（字符串形式）并验证其是否有效。有效含义正确形成的 JSON 数据。

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CREATE TABLE locations (
    id INT NOT NULL AUTO_INCREMENT,
    name VARCHAR(100) NOT NULL,
    type CHAR(1) NOT NULL,
    latitude DECIMAL(9,6) NOT NULL,
    longitude DECIMAL(9,6) NOT NULL,
    attr LONGTEXT CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL
    CHECK (JSON_VALID(`attr`)
     PRIMARY KEY (id)
);

Note that the data type of the attr column is LONGTEXT . In addition to this, you'll find some constraints added to the character set and collation fields. The most important, however, is the CHECK constraint, which indicates the function that will be executed when the data in attr is modified by insert or update.
The JSON_VALID() function is a predefined function that receives JSON data (as a string) and verifies that it is valid. Valid meaning Correctly formed JSON data.