Tag Archives: Web

How to Solve mybatis-plus Paging Plug-in PaginationInnerInterceptor error

Questions

mybatis-plus using PaginationInnerInterceptor paging plugin, when calling the paging query method (****Service.page(new Page(param.getPage(),param.getPageSize()),queryWrapper )) reports the following error:

 2022-07-22 17:07:20.699 [TID: N/A]  WARN 12444 --- [io-18080-exec-1] c.b.m.e.p.i.PaginationInnerInterceptor   : optimize this sql to a count sql has exception, sql:"sql语句略", exception:
net.sf.jsqlparser.parser.ParseException: Encountered unexpected token: "," ","
    at line 1, column 191.

Was expecting one of:

    "&"
    "::"
    ";"
    "<<"
    ">>"
    "ACTION"
    "ACTIVE"
    "ALGORITHM"
    "ARCHIVE"
    "ARRAY" 
    ***略****

reason

The paging plugin will default to sql optimization when processing count, and will throw an exception if optimization fails. The sql that cannot be optimized will be downgraded to the non-optimized count method.
The code summary is as follows.
where Select select = (Select) CCJSqlParserUtil.parse(sql); This line of code reports error:

    protected String autoCountSql(IPage<?> page, String sql) {
        if (!page.optimizeCountSql()) {
            return lowLevelCountSql(sql);
        }
        try {
            Select select = (Select) CCJSqlParserUtil.parse(sql);
            **************Optimization Logic*********************
            return select.toString();
        } catch (JSQLParserException e) {
            // Unable to optimize the use of the original SQL
            logger.warn("optimize this sql to a count sql has exception, sql:\"" + sql + "\", exception:\n" + e.getCause());
        } catch (Exception e) {
            logger.warn("optimize this sql to a count sql has error, sql:\"" + sql + "\", exception:\n" + e);
        }
        return lowLevelCountSql(sql);
    }

Solution:

Add the following codes before your codes:

if (!page.optimizeCountSql()) {
return lowLevelCountSql(sql);
}

just set optimizeCountSql to false, as follows

Page page = new Page(param.getPage(),param.getPageSize()),queryWrapper)
page.setOptimizeCountSql(false);

You can also redefine a class to inherit Page, and set optimizeCountSql default to =false

 

[Solved] IDEA Error: Unknown system variable ‘tx_isolation‘ at

IDEA Error: Unknown system variable ‘tx_isolation’ at

java.sql.SQLException: Unknown system variable ‘tx_isolation’ at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1094) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4208) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4140) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2597) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2758) at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2820) at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2769) at com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1569) at com.mysql.jdbc.ConnectionImpl.getTransactionIsolation(ConnectionImpl.java:3372) at com.mchange.v2.c3p0.impl.NewPooledConnection.(NewPooledConnection.java:107) at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:198) at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:171) at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137) at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014) at com.mchange.v2.resourcepool.BasicResourcePool.access800 ( B a s i c R e s o u r c e P o o l . j a v a : 32 ) a t c o m . m c h a n g e . v 2. r e s o u r c e p o o l . B a s i c R e s o u r c e P o o l 800(BasicResourcePool.java:32) at com.mchange.v2.resourcepool.BasicResourcePool800(BasicResourcePool.java:32)atcom.mchange.v2.resourcepool.BasicResourcePoolAcquireTask.run(BasicResourcePool.java:1810) at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)

 

Solution:
1. the version of mysql-connector-java is too low and you need to upgarde to version 8.0.*
2. After you had upgraded the version of mysql-connector-java, update the driver:
com.mysql.jdbc.Driver——>com.mysql.cj.jdbc.Driver

[Solved] MSBUILD : error MSB3428: Could not load the Visual C++ component “VCBuild.exe“

MSBUILD : error MSB3428: Could not load the Visual C++ component “VCBuild.exe”.

This problem occurs in the install front-end project

MSBUILD : error MSB3428: Could not load the Visual C++ component “VCBuild.exe”…

Solution:

1. The administrator opens CMD and sets the agent (optional, if you have one)

set HTTP_PROXY=http://127.0.0.1:1080
set HTTPS_PROXY=http://127.0.0.1:1080

2. Install windows build tool

npm install -g --production windows-build-tools

3. If the card is completely stuck, wait for one minute, and then enter C:\Users\Username\.windows-build-tools

If there is a file in the figure below, the download is successful, and if there is no file, the download fails

If the download fails, download it manually and extract it to C:\Users\Username\

The final status is shown in the figure:

5 Configure system environment variables (Setting -> advanced system settings -> environment variables)

Append to path item

​ C:\Users\13261.windows-build-tools

​ C:\Users\13261.windows-build-tools\python27

6. change the file name

Because the problem I encountered was MSBUILD : error MSB3428: Could not load the Visual C++ component “VCBuild.exe”…

The project will use the executable file VCBuild.exe to build

So I made a copy of vs_BuildTools.exe and modified it to VCBuild.exe, so that cmd can use “VCBuild”!

Because I have already installed python3 or higher, the command is also “python”

so python2.7 I will also modify the executable to python.exe -> python2.exe, pythonw.exe -> python2w.exe

TIP: If your front-end project will be built with commands like “python2” or “python3” instead of “python” to execute python code, then you also need to rename the executable

Translated with www.DeepL.com/Translator (free version)

[Solved] Vue 3 Script Setup ESLint Error: ‘defineProps‘ is not defined

Solution: when using Vue 3 script setup, eslint reports the error ‘defineprops’ is not defined

Vue 3’s script setup syntax introduces compiler macros of defineprops, definemits, defineexpose, withdefaults. However, in some cases, eslint will report an error. The above compiler macro functions are not defined.

This article will introduce two solutions to solve this problem (assuming that your project is initialized with Vue CLI).

Step 1. Check the version of eslint-plugin-Vue 

npm list eslint-plugin-vue

If the version is in V8 Above 0.0, jump to step 2, otherwise go directly to the content of step 3.

Step 2. Version is V8.0.0+

Open eslintrc.JS file and modify it as follows:

  env: {
    node: true,
    // The Follow config only works with eslint-plugin-vue v8.0.0+
    "vue/setup-compiler-macros": true,
  },

Step 3. Version is V8 Below 0.0

Open eslintrc.JS file and modify it as follows:

  // The Follow configs works with eslint-plugin-vue v7.x.x
  globals: {
    defineProps: "readonly",
    defineEmits: "readonly",
    defineExpose: "readonly",
    withDefaults: "readonly",
  },

If your version of  eslint-plugin-vue is under V8, I don’t recommended you to upgrade the version，especially you had used a lot of ts dependency.

[Solved] ECharts Console Error: `resize` should not be called during main process

When using ecarts, the console reports an error ` resize ` should not be called during main process

This situation may occur in the scenario where echarts is used in combination with Vue 3, especially after the echarts instance is wrapped with Ref.

This article is excerpted from another blog post, the use of echarts 5 in the development of Vue 3

1. Problem analysis

In general, the encapsulation of ecarts chart does not need to expose the ecarts object to the rendering context. If you do intend to declare an echots object as a response, use shallowref instead of ref:

// GOOD
const chart = shallowRef<echarts.ECharts>(); 

// BAD
const chart = ref<echarts.ECharts>();

If you do not use shallowref, the command line may report an error ‘resize’ should not be called during main process; In fact, any instance created by a third-party library should be processed responsively using shallowref instead of ref.

[Solved] npm link Error: error Error: EPERM: operation not permitted；The operation was rejected by your operating

Error message:

Solution:

From the error message, the prompt is that the permission is insufficient to operate. All the files found on the Internet are to delete npmrc files, but there is no effect. Through exploration, we can solve it in two ways:
1. Run vscode as an administrator, and then run NPM link on the vscode terminal
2. Run CMD (command prompt) as an administrator, Go into your own module and run NPM link

it’s done

[Solved] cURL error 60: SSL certificate problem: unable to get local issuer certificate

When the PHP server curl is based on the HTTPS protocol API, this problem will be reported if the environment does not handle it:

cURL error 60: SSL certificate problem: unable to get local issuer certificate

Solution:
(1) download the file used to support HTTPS

(2) Place the file in a location, such as “C:\env\cacert.PEM”

(3) Modify php.ini and add support for cacert.pem

[Solved] Binding onclick event in JS: for loop: error uncaught typeerror: cannot set properties of undefined (setting ‘classname’)

I want to achieve the following effects: click the column above to switch the content of the column below

Write the code as follows (mainly see the JS part)

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .tab{
            display: inline-block;
            width: 100px;
            height: 50px;
            background-color: #aaa;
        }
        .current{
            background-color: yellow;
        }
        .content{
            display: none;
        }
    </style>
</head>
<body>
    <div class = "tab">
        <div class = "tab_list">
            <li>栏目1</li>
            <li>栏目2</li>
            <li>栏目3</li>
        </div>
        <div class = "tab_con" style="display: block;">栏目1的内容</div>
        <div class = "tab_con">栏目2的内容</div>
        <div class = "tab_con">栏目3的内容</div>
    </div>

    <script>
        var tab_list = document.querySelector(".tab_list").querySelectorAll("li");
        var tab_con = document.querySelectorAll(".tab_con");
        
        for(var i = 0;i<tab_list.length;i++){
            tab_list[i].onclick = function(){
                for(var j = 0;j<tab_list.length;j++){
                    tab_list[j].className = "tab";
                }
                tab_list[i].className = "tab red";

                for(var j = 0;j<tab_con.length;j++){
                    tab_con[j].style.display = "none";
                }
                tab_con[i].style.display = "block";

            }
        }



    </script>
</body>
</html>

The result shows an error: uncaught typeerror: cannot set properties of undefined (setting 'classname') at htmldivelement.Tab.<computed>.onclick

Baidu tested it and found the following code:

<script>
        var tab_list = document.querySelector(".tab_list").querySelectorAll("li");
        var tab_con = document.querySelectorAll(".tab_con");
        
        for(var i = 0;i<tab_list.length;i++){
            tab_list[i].onclick = function(){
                console.log("栏目" + i + "被点击了");
            }
        }



    </script>

In printing, I is 3 instead of 0, 1 and 2.

After consulting the data, we know that:

In the for loop, for each tab_List is bound to the onclick event to listen, but when the function is executed, I has ended the loop, so the printout is 3.

That is, the event listening function in the for loop needs to avoid using the loop variable I

So, if tab is involved_List [i], we can use this; If tab is involved_Con [i], that is, use I to get other elements, so we can give tab_List adds an attribute index, and then in the onclick function, we get this attribute, that is, we get the I we want

The code is as follows:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        .tab{
            width: 400px;
            margin: 100px auto;
        }
        .tab .tab_list li{
            display: inline-block;
            width: 100px;
            height: 50px;
            line-height: 50px;
            text-align: center;
            background-color: #aaa;
        }
        .tab .tab_list .current{
            background-color: yellow;
        }
        .content{
            display: none;
        }
    </style>
</head>
<body>
    <div class = "tab">
        <div class = "tab_list">
            <li>栏目1</li>
            <li>栏目2</li>
            <li>栏目3</li>
        </div>
        <div class = "tab_con" style="display: block;">栏目1的内容</div>
        <div class = "tab_con">栏目2的内容</div>
        <div class = "tab_con">栏目3的内容</div>
    </div>

    <script>
        var tab_list = document.querySelector(".tab_list").querySelectorAll("li");
        var tab_con = document.querySelectorAll(".tab_con");
        
        for(var i = 0;i<tab_list.length;i++){
            tab_list[i].setAttribute("index",i);
            tab_list[i].onclick = function(){
                var index = this.getAttribute("index");
                console.log("栏目" + index + "被点击了");
                for(var j = 0;j<tab_list.length;j++){
                    tab_list[j].className = "";
                }
                tab_list[index].className = "current";
                console.log(this.className);
                for(var j = 0;j<tab_con.length;j++){
                    tab_con[j].style.display = "none";
                }
                tab_con[index].style.display = "block";

            }
        }
    </script>
</body>
</html>

[Solved] Druid register MBean error: ERROR [com.alibaba.druid.stat.DruidDataSourceStatManager]

It is normal to run a Tomcat project. When running two Tomcat projects, an exception will be reported.

ERROR [com.alibaba.druid.stat.DruidDataSourceStatManager] – unregister mbean error javax.management.InstanceNotFoundException: com.alibaba.druid:type=DruidDataSourceStat at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.getMBean………

Solution:

Modify catalina.sh under Tomcat: add and set Java at the end_OPTS="Ddruid.registerToSysProperty=true"

This method is effective in personal test. If it is added in other places, it is not guaranteed to be effective