1.一般來說MySQL(小於5.5.3)字符集設置爲utf8,指定連接的字符集也爲utf8，django中save unicode string是木有問題的。但是，當字符串中有特殊字符（如emoji表情符號，以及其他凡是轉成utf8要佔用4字節的字符），就會有問題，會報錯Incorrect string value: '\xF0\x9F\x92\x90</...' for column 'xxx' at row 1
大家都知道Unicode是一個標準，utf8是unicode一個實現方式, 某些Unicode字符轉成utf8可能4字節，而在MySQl5.5.3之前，utf8最長只有3字節。
mysql> show character set;
+------------+----------------------------+------------------------+----------+
| Charset | Description | Default collation | Maxlen |
+------------+----------------------------+------------------------+----------+
| utf8 | UTF-8 Unicode | utf8_general_ci | 3 |
+------------+----------------------------+------------------------+----------+
所以呢，這個需要4字節才能表示的Unicode字符會被截斷，存不進去。
2. 低版本Mysql<5.5.3貌似沒啥好辦法，把字段類型改爲 MEDIUMBLOB ， 其他啥都不用改(繼續保持數據庫字符集和連接字符集都是utf8)，問題解決。見下圖，
<code><span class="pln">mysql</span><span class="pun">></span><span class="pln"> show variables like </span><span class="str">'char%'</span><span class="pun">;</span><span class="pln"> </span><span class="pun">+--------------------------+----------------------------+</span><span class="pln"> </span><span class="pun">|</span><span class="pln"> </span><span class="typ">Variable_name</span><span class="pln"> </span><span class="pun">|</span><span class="pln"> </span><span class="typ">Value</span><span class="pln"> </span><span class="pun">|</span><span class="pln"> </span><span class="pun">+--------------------------+----------------------------+</span><span class="pln"> </span><span class="pun">|</span><span class="pln"> character_set_client </span><span class="pun">|</span><span class="pln"> utf8 </span><span class="pun">|</span><span class="pln"> </span><span class="pun">|</span><span class="pln"> character_set_connection </span><span class="pun">|</span><span class="pln"> utf8 </span><span class="pun">|</span><span class="pln"> </span><span class="pun">|</span><span class="pln"> character_set_database </span><span class="pun">|</span><span class="pln"> utf8 </span><span class="pun">|</span><span class="pln"> </span><span class="pun">|</span><span class="pln"> character_set_filesystem </span><span class="pun">|</span><span class="pln"> binary </span><span class="pun">|</span><span class="pln"> </span><span class="pun">|</span><span class="pln"> character_set_results </span><span class="pun">|</span><span class="pln"> utf8 </span><span class="pun">|</span><span class="pln"> </span><span class="pun">|</span><span class="pln"> character_set_server </span><span class="pun">|</span><span class="pln"> utf8 </span><span class="pun">|</span><span class="pln"> </span><span class="pun">|</span><span class="pln"> character_set_system </span><span class="pun">|</span><span class="pln"> utf8 </span><span class="pun">|</span><span class="pln"> </span><span class="pun">|</span><span class="pln"> character_sets_dir </span><span class="pun">|</span><span class="pln"> </span><span class="str">/usr/</span><span class="pln">share</span><span class="pun">/</span><span class="pln">mysql</span><span class="pun">/</span><span class="pln">charsets</span><span class="pun">/</span><span class="pln"> </span><span class="pun">|</span><span class="pln"> </span><span class="pun">+--------------------------+----------------------------+</span></code>這個狀態下 MEDIUMBLOB 就能搞定。
3.MySQl>=5.5.3，則可以不用像上面那麼做。
3.1 修改mysql配置文件，設置默認字符集utf8mb4, 包括collation
[client]
default-character-set = utf8mb4
[mysql]
default-character-set = utf8mb4
[mysqld]
character-set-client-handshake = FALSE
character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci
init_connect='SET NAMES utf8mb4'
3.2 重啓，確認上述配置生效
mysql> SHOW VARIABLES WHERE Variable_name LIKE 'character\_set\_%' OR Variable_name LIKE 'collation%';
+-------------------------------------+------------------------------+
| Variable_name | Value |
+-------------------------------------+------------------------------+
| character_set_client | utf8mb4 |
| character_set_connection | utf8mb4 |
| character_set_database | utf8mb4 |
| character_set_filesystem | binary |
| character_set_results | utf8mb4 |
| character_set_server | utf8mb4 |
| character_set_system | utf8 |
| collation_connection | utf8mb4_unicode_ci |
| collation_database | utf8mb4_unicode_ci |
| collation_server | utf8mb4_unicode_ci |
+-------------------------------------+-------------------------------+
其他不用改，都用 utf8mb4 ， django中任意Unicode字符都能存入MySQL。
思路：判斷你的MySQL utf8最大長度是不是4，
如果不是，支不支持utf8mb4,
如果不支持，升級 or MEDIUMBLOB
其實這個問題，網上已經太多了，沒啥好寫的，記一筆，僅爲個人成長記錄。
喫水不忘挖井人，修bug時參考了這兩篇文章。
http://vivisidea.iteye.com/blog/1395571
http://www.linuxidc.com/Linux/2013-05/84360.htm
轉載：http://blog.csdn.net/secretx/article/details/21253559