How To Insert Code Snippets in Blogger Post

Posted on 2020-10-24 by robin

There’s no native way to insert codes in Blogger (ie – no button on the editor toolbar). However we can manage to overcome the problem.

The easiest way is to write the full content in markdown and then copy it into the blog editor. It comes with full syntax highlighting in the language of your choice.

For example, we can write java code like this:

    ```java
    public class MyApp {
    
        public static void main(String[] args) {
            System.out.println("Hello World!");
        }
        
    }
    ```

```java

public class MyApp {

public static void main(String[] args) {

System.out.println("Hello World!");

}

```

And the result:

public class MyApp {
    
    public static void main(String[] args) {
        System.out.println("Hello World!");
    }
        
}

public class MyApp {

public static void main(String[] args) {

System.out.println("Hello World!");

}

Continue reading →

SpringBoot Mybatis Insert null Fields

Posted on 2020-10-24 by robin

I’m using SpringBoot and MyBatis. When tried to insert/update some rows into a table, I got the fllowing:

org.springframework.dao.DataIntegrityViolationException: 
### Error updating database.  Cause: java.sql.SQLIntegrityConstraintViolationException: Column 'remark' cannot be null
### The error may exist in org/chobit/service/mapper/UserMapper.java (best guess)
### The error may involve org.chobit.service.mapper.UserMapper.updateById-Inline
### The error occurred while setting parameters
### SQL: update user set  username=?, `remark`=? where id=?
### Cause: java.sql.SQLIntegrityConstraintViolationException: Column 'remark' cannot be null
; Column 'remark' cannot be null; nested exception is java.sql.SQLIntegrityConstraintViolationException: Column 'remark' cannot be null
	at org.springframework.jdbc.support.SQLExceptionSubclassTranslator.doTranslate(SQLExceptionSubclassTranslator.java:87)
	at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:72)
	at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:81)
	at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:73)
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:446)
	at com.sun.proxy.$Proxy88.update(Unknown Source)
	at org.mybatis.spring.SqlSessionTemplate.update(SqlSessionTemplate.java:294)
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:67)

org.springframework.dao.DataIntegrityViolationException:

### Error updating database. Cause: java.sql.SQLIntegrityConstraintViolationException: Column 'remark' cannot be null

### The error may exist in org/chobit/service/mapper/UserMapper.java (best guess)

### The error may involve org.chobit.service.mapper.UserMapper.updateById-Inline

### The error occurred while setting parameters

### SQL: update user set username=?, `remark`=? where id=?

### Cause: java.sql.SQLIntegrityConstraintViolationException: Column 'remark' cannot be null

; Column 'remark' cannot be null; nested exception is java.sql.SQLIntegrityConstraintViolationException: Column 'remark' cannot be null

at org.springframework.jdbc.support.SQLExceptionSubclassTranslator.doTranslate(SQLExceptionSubclassTranslator.java:87)

at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:72)

at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:81)

at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:73)

at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:446)

at com.sun.proxy.$Proxy88.update(Unknown Source)

at org.mybatis.spring.SqlSessionTemplate.update(SqlSessionTemplate.java:294)

at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:67)

The column remark in the table user was setted to NOT NULL, and the value of the column to insert was null. That’s why I received the error. Continue reading →

How to make Jackson to avoid Escaping Backslash

Posted on 2020-10-24 by robin

As I tried to deserialize a json string from database with jackson, I received error message like this:

Exception in thread "main" com.fasterxml.jackson.core.JsonParseException: Unrecognized character escape 'W' (code 87)
 at [Source: (String)"{"text":"Hello \World!"}"; line: 1, column: 18]
	at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1840)
	at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:712)
	at com.fasterxml.jackson.core.base.ParserBase._handleUnrecognizedCharacterEscape(ParserBase.java:1031)
	at com.fasterxml.jackson.core.json.ReaderBasedJsonParser._decodeEscaped(ReaderBasedJsonParser.java:2545)
	at com.fasterxml.jackson.core.json.ReaderBasedJsonParser._finishString2(ReaderBasedJsonParser.java:2066)
	at com.fasterxml.jackson.core.json.ReaderBasedJsonParser._finishString(ReaderBasedJsonParser.java:2039)
	at com.fasterxml.jackson.core.json.ReaderBasedJsonParser.getText(ReaderBasedJsonParser.java:294)
	at com.fasterxml.jackson.databind.deser.std.UntypedObjectDeserializer$Vanilla.deserialize(UntypedObjectDeserializer.java:672)
	at com.fasterxml.jackson.databind.deser.std.MapDeserializer._readAndBindStringKeyMap(MapDeserializer.java:527)
	at com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:364)
	at com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:29)
	at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4202)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3205)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3173)
	at org.chobit.calf.MyApp.main(MyApp.java:23)

Exception in thread "main" com.fasterxml.jackson.core.JsonParseException: Unrecognized character escape 'W' (code 87)

at [Source: (String)"{"text":"Hello \World!"}"; line: 1, column: 18]

at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1840)

at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:712)

at com.fasterxml.jackson.core.base.ParserBase._handleUnrecognizedCharacterEscape(ParserBase.java:1031)

at com.fasterxml.jackson.core.json.ReaderBasedJsonParser._decodeEscaped(ReaderBasedJsonParser.java:2545)

at com.fasterxml.jackson.core.json.ReaderBasedJsonParser._finishString2(ReaderBasedJsonParser.java:2066)

at com.fasterxml.jackson.core.json.ReaderBasedJsonParser._finishString(ReaderBasedJsonParser.java:2039)

at com.fasterxml.jackson.core.json.ReaderBasedJsonParser.getText(ReaderBasedJsonParser.java:294)

at com.fasterxml.jackson.databind.deser.std.UntypedObjectDeserializer$Vanilla.deserialize(UntypedObjectDeserializer.java:672)

at com.fasterxml.jackson.databind.deser.std.MapDeserializer._readAndBindStringKeyMap(MapDeserializer.java:527)

at com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:364)

at com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:29)

at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4202)

at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3205)

at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3173)

at org.chobit.calf.MyApp.main(MyApp.java:23)

The json string is:

{"text":"Hello \World!"}

1	{"text":"Hello \World!"}

It’s the Backslash in the source json string which lead to the error. Continue reading →