mybatis-plus支持null字段全量更新的两种方法

userService.update(
                Wrappers.lambdaUpdate(user)
                        .set(User::getUserName, null)
                        .eq(User::getId,"0001"));

public class WrappersFactory {

    private final static List<String> ignoreList = new ArrayList<>();

    static {
        ignoreList.add(CommonField.available);
        ignoreList.add(CommonField.create_time);
        ignoreList.add(CommonField.create_username);
        ignoreList.add(CommonField.update_time);
        ignoreList.add(CommonField.update_username);
        ignoreList.add(CommonField.create_user_code);
        ignoreList.add(CommonField.update_user_code);
        ignoreList.add(CommonField.deleted);
    }

    public static <T> LambdaUpdateWrapper<T> updateWithNullField(T entity) {
        UpdateWrapper<T> updateWrapper = new UpdateWrapper<>();
        List<Field> allFields = TableInfoHelper.getAllFields(entity.getClass());
        MetaObject metaObject = SystemMetaObject.forObject(entity);
        for (Field field : allFields) {
            if (!ignoreList.contains(field.getName())) {
                Object value = metaObject.getValue(field.getName());
                updateWrapper.set(StringUtils.camelToUnderline(field.getName()), value);
            }
        }
        return updateWrapper.lambda();
    }
}

userService.update(WrappersFactory.updateWithNullField(user).eq(User::getId,"0001"));

public class UpdateWithNull extends AbstractMethod {
    @Override
    public MappedStatement injectMappedStatement(Class<?> mapperClass, Class<?> modelClass, TableInfo tableInfo) {
        //具体的字段逻辑在这里处理,实际上就是在这里构造一个新的statement
        return null;
    }
}

public interface CommonMapper <T> extends BaseMapper<T> {

    /**
     * 根据 whereEntity 条件，更新记录
     *
     * @param entity        实体对象 (set 条件值,可以为 null)
     * @param updateWrapper 实体对象封装操作类（可以为 null,里面的 entity 用于生成 where 语句）
     */
    int updateWithNull(@Param(Constants.ENTITY) T entity, @Param(Constants.WRAPPER) Wrapper<T> updateWrapper);

}

public class CustomSqlInjector extends AbstractSqlInjector {
    @Override
    public List<AbstractMethod> getMethodList() {
        return Stream.of(
                new Insert(),
                new Delete(),
                new DeleteByMap(),
                new DeleteById(),
                new DeleteBatchByIds(),
                new Update(),
                new UpdateWithNull(),
                new UpdateById(),
                new SelectById(),
                new SelectBatchByIds(),
                new SelectByMap(),
                new SelectOne(),
                new SelectCount(),
                new SelectMaps(),
                new SelectMapsPage(),
                new SelectObjs(),
                new SelectList(),
                new SelectPage()
        ).collect(toList());
    }
}

public String getSqlSet(final String prefix) {
        final String newPrefix = prefix == null ? EMPTY : prefix;
        // 默认: column=
        String sqlSet = column + EQUALS;
        if (StringUtils.isNotEmpty(update)) {
            sqlSet += String.format(update, column);
        } else {
            sqlSet += SqlScriptUtils.safeParam(newPrefix + el);
        }
        sqlSet += COMMA;
        if (fieldFill == FieldFill.UPDATE || fieldFill == FieldFill.INSERT_UPDATE) {
            // 不进行 if 包裹
            return sqlSet;
        }
        return convertIf(sqlSet, newPrefix + property);
    }

final List<TableFieldInfo> fieldList = tableInfo.getFieldList();
        for (final TableFieldInfo tableFieldInfo : fieldList) {
            final Class<? extends TableFieldInfo> aClass = tableFieldInfo.getClass();
            try {
                final Field fieldFill = aClass.getDeclaredField("fieldFill");
                fieldFill.setAccessible(true);
                fieldFill.set(tableFieldInfo, FieldFill.UPDATE);
            } catch (final NoSuchFieldException e) {
                log.error("获取fieldFill失败", e);
            } catch (final IllegalAccessException e) {
                log.error("设置fieldFill失败", e);
            }
        }

@Slf4j
public class UpdateWithNull extends AbstractMethod {
    @Override
    public MappedStatement injectMappedStatement(Class<?> mapperClass, Class<?> modelClass, TableInfo tableInfo) {
        SqlMethod sqlMethod = SqlMethod.UPDATE;

        final List<TableFieldInfo> fieldList = tableInfo.getFieldList();
        for (final TableFieldInfo tableFieldInfo : fieldList) {
            final Class<? extends TableFieldInfo> aClass = tableFieldInfo.getClass();
            try {
                final Field fieldFill = aClass.getDeclaredField("fieldFill");
                fieldFill.setAccessible(true);
                fieldFill.set(tableFieldInfo, FieldFill.UPDATE);
            } catch (final NoSuchFieldException e) {
                log.error("获取fieldFill失败", e);
            } catch (final IllegalAccessException e) {
                log.error("设置fieldFill失败", e);
            }
        }

        String sql = String.format(sqlMethod.getSql(), tableInfo.getTableName(),
                sqlSet(true, true, tableInfo, true, ENTITY, ENTITY_DOT),
                sqlWhereEntityWrapper(true, tableInfo));
        SqlSource sqlSource = languageDriver.createSqlSource(configuration, sql, modelClass);
        return addUpdateMappedStatement(mapperClass, modelClass, sqlMethod.getMethod(), sqlSource);
    }
}