一個簡單的python MVC架構(1)

標籤：

因為買了本機器學習的書是python的，所以學習了一下python，就用python做了一個簡單的web開發的mvc小架構。整個架構分為實體層，資料訪問層，業務基類層，Web請求轉寄層，控制層和視圖層。當然也包括一些輔助性工具類。下面一一介紹，希望對跟我一樣初學python的有點協助：
1）實體層
      由實體基類和使用者實體類組成。實體類可以由資料庫自動產生，提供了一個DbTools，可以自動建置規則的實體。下面是實體基類：
    

import threading#使用者錯誤類，用於拋出自訂的異常class CustomError(RuntimeError):      def __init__(self,args):          self.args=args#實體的基類.          class EntityB:    def __init__(self):        self.CurrFields=[]    #根據屬性名稱擷取屬性值    def GetValueByName(self,FieldName):        if hasattr(self,FieldName):            return getattr(self,FieldName)        return None    #根據屬性名稱設定屬性值    def SetValueByName(self,FieldName,Value):        if hasattr(self,FieldName):            return setattr(self,FieldName,Value)    #定義了該屬性，對象可枚舉.    def __getitem__(self,key):        if type(key)==type(‘abc‘):            return self.GetValueByName(key)        if type(key)==type(1):            theFld = self.CurrFields[key]            return self.GetValueByName(theFld)        return None    #設定屬性值,key可以是索引，也可以是屬性名稱.    def __setitem__(self,key,value):        if type(key)==type(‘abc‘):            self.SetValueByName(key,value)        if type(key)==type(1):            theFld = self.CurrFields[key]            self.SetValueByName(theFld,value)    #擷取實體的表名.    def GetTableName(self):        theType = type(self)        if hasattr(theType,‘TableName‘):            return getattr(theType,‘TableName‘)        return ‘‘    #擷取關鍵字段名    def GetKeyField(self):        theType = type(self)        if hasattr(theType,‘KeyField‘):            return getattr(theType,‘KeyField‘)        return ‘‘    #擷取欄位名集合    def GetFields(self):        theType = type(self)        if hasattr(theType,‘Fields‘):            return getattr(theType,‘Fields‘)        return []        InsertCondition = threading.Condition()    InsertLockSign = False        DeleteCondition = threading.Condition()    DeleteLockSign = False    UpdateAllCondition = threading.Condition()    UpdateAllLockSign = False        InsertSqlName=‘__InsertSql‘    UpdateAllSqlName=‘__UpdateSql‘    DelByPKSqlName=‘__DelByPKSql‘    DefaultSelectSQL=‘__DefaultSelectSql‘    #根據屬性名稱擷取類型的屬性值。    def _GetClassValue(self,AttrName):        theSelfType = type(self)        theValue =‘‘        if hasattr(theSelfType,AttrName):           theValue=getattr(theSelfType,AttrName)        return theValue    #根據屬性名稱設定類型的屬性值.    def _SetClassValue(self,AttrName,value):        theSelfType = type(self)        theValue =‘‘        if hasattr(theSelfType,AttrName):           setattr(theSelfType,AttrName,value)    #擷取欄位參數    def GetFieldParams(self):        return self._GetClassValue(‘FieldParams‘)    #擷取插入的SQL    def GetInsertSQL(self):        theSQL =self._GetClassValue(EntityB.InsertSqlName)        if (theSQL==None or theSQL==‘‘):           EntityB.InsertCondition.acquire()           try:               if EntityB.InsertLockSign:                   EntityB.InsertCondition.wait()               InsertLockSign = True               theSQL =self._GetClassValue(EntityB.InsertSqlName)               if (theSQL==None or theSQL==‘‘):                   theTableName=self.GetTableName()                   theFields=self.GetFields()                   if theTableName==‘‘ or theFields==[]:                       raise CustomError(‘表名或欄位為空白！‘)                   theSQL=‘INSERT INTO ‘+ theTableName                   theFlds=‘‘                   theVals=‘‘                   theFldParams = self.GetFieldParams()                   for theF in theFields:                       if theFlds==‘‘:                           theFlds += theF                           theVals += theFldParams[theF][‘DSFmt‘]                       else:                           theFlds += ‘,‘+theF                           theVals +=‘,‘+theFldParams[theF][‘DSFmt‘]                   theSQL+=‘(‘+theFlds+‘) values(‘+theVals+‘)‘                   self._SetClassValue(EntityB.InsertSqlName,theSQL)               return theSQL           finally:               InsertLockSign=False               EntityB.InsertCondition.notify()               EntityB.InsertCondition.release()        else:           return theSQL    #擷取根據主鍵刪除SQL    def GetDelByPKSQL(self):        theSQL =self._GetClassValue(EntityB.DelByPKSqlName)        if (theSQL==None or theSQL==‘‘):           EntityB.DeleteCondition.acquire()           try:               if EntityB.DeleteLockSign:                   EntityB.DeleteCondition.wait()               DeleteLockSign = True               theSQL =self._GetClassValue(EntityB.DelByPKSqlName)               if (theSQL==None or theSQL==‘‘):                   theTableName=self.GetTableName()                   theKeyField=self.GetKeyField()                   if theTableName==‘‘ or theKeyField==‘‘:                       raise CustomError(‘表名或主鍵為空白！‘)                   theFldParams = self.GetFieldParams()                   theSQL=‘DELETE FROM ‘+ theTableName+‘ WHERE ‘+theKeyField+‘=‘+theFldParams[theKeyField][‘DSFmt‘]                   self._SetClassValue(EntityB.DelByPKSqlName,theSQL)               return theSQL           finally:               DeleteLockSign=False               EntityB.DeleteCondition.notify()               EntityB.DeleteCondition.release()        else:           return theSQL    #擷取更新所有欄位的SQL語句(根據主鍵更新)    def GetUpdateAllSQL(self):        theSQL =self._GetClassValue(EntityB.UpdateAllSqlName)        if (theSQL==None or theSQL==‘‘):           EntityB.UpdateAllCondition.acquire()           try:               if EntityB.UpdateAllLockSign:                   EntityB.UpdateAllCondition.wait()               UpdateAllLockSign = True               theSQL =self._GetClassValue(EntityB.UpdateAllSqlName)               if (theSQL==None or theSQL==‘‘):                   theTableName=self.GetTableName()                   theFields=self.GetFields()                   theKeyField=self.GetKeyField()                   if theTableName==‘‘ or theFields==[] or theKeyField==‘‘:                       raise CustomError(‘表名、主鍵或欄位為空白！‘)                   theSQL=‘UPDATE ‘+ theTableName +‘ SET ‘                   theFlds=‘‘                   theFldParams = self.GetFieldParams()                   for theF in theFields:                       if(theF != theKeyField):                           if theFlds==‘‘:                               theFlds += theF+‘= ‘+theFldParams[theF][‘DSFmt‘]                           else:                               theFlds += ‘,‘+theF+‘= ‘+theFldParams[theF][‘DSFmt‘]                   theSQL+= theFlds +‘ WHERE ‘+theKeyField+‘=‘+theFldParams[theKeyField]                   self._SetClassValue(EntityB.UpdateAllSqlName,theSQL)               return theSQL           finally:               UpdateAllLockSign=False               EntityB.UpdateAllCondition.notify()               EntityB.UpdateAllCondition.release()        else:           return theSQL    #擷取預設的查詢SQL    def GetDefaultSelectSQL(self):        theTableName=self.GetTableName()        return ‘SELECT * FROM ‘ + theTableName + ‘ WHERE 1=1‘    #def __delitem__(self)           

有關實體的通用操作SQL都是動態產生的，但不是每次都去產生，而是緩衝在類型下。所為實體，做如下建議：
1）通用的SQL可以先產生，或者動態產生，但緩衝；
2）一般查詢SQL，特別是帶條件的，盡量不要動態產生，也不要使用類似EF架構的那種，無論是管理效能還是擴充都是災難；
3）一般不要把實體關聯固化，如早期Hibernate的那種方式，就是在資料庫裡也不要建外間關係，去根據業務需要轉化為商務邏輯，一般系統大一點，或者在分布式結構下，去固化實體關聯，或者把實體關聯映射放到記憶體或者設定檔中，都是一種災難。

下面的類是協助工具輔助類：

#Generate entitiesimport BusinessBasedef GetFmtStr(datatype):    if datatype.find(‘varchar‘)>=0:        return ‘%s‘    elif datatype.find(‘date‘)>=0:        return ‘%s‘    else:        return ‘%s‘def IntToStr(iData=0):    if iData==None:        return ‘0‘    return ‘%d‘ % iData;theFile = open(r"EntitiesL.py", "w")try:    theDb = BusinessBase.BusinessBase(object)    #這裡需改為從你自己的資料庫XXXX    theTabs = theDb.GetDbTables(‘XXXX‘)    theFile.write("import EntityBase\n")        for theTab in theTabs:        theFile.write(‘class M_‘+theTab.TableName.upper()+‘(EntityBase.EntityB):\n‘)        theFile.write(‘    def __init__(self):\n‘)        theFile.write(‘        M_‘+theTab.TableName.upper()+‘.Count += 1\n‘)        theFile.write(‘        self.RefDict={}\n‘)        theFile.write(‘        self.CurrFields=[]\n‘)        theFile.write(‘    Count=0\n‘)            theFile.write(‘    TableName =\‘‘+theTab.TableName+‘\‘\n‘)        theKeyField=‘‘        theFlds=‘‘        theFile.write(‘    FieldParams={\n‘)         theFields=theDb.GetTabFields(‘tian‘,theTab.TableName)        theIndex =0        for theF in theFields:            if theF.iskey==1:                theKeyField = theF.column_name                            theIndex += 1            if(theIndex>1):                theFile.write(‘                        ,\n‘)                theFlds+=‘,\‘‘+theF.column_name+‘\‘‘            else:                theFlds=‘\‘‘+theF.column_name+‘\‘‘            theFile.write(‘                  \‘‘+theF.column_name+‘\‘:\n‘)            theFile.write(‘                        {\n‘)            theFile.write(‘                        \‘DSFmt\‘:\‘‘+GetFmtStr(theF.data_type)+‘\‘,\n‘)            theFile.write(‘                        \‘DataType\‘:\‘‘+theF.data_type+‘\‘,\n‘)            theFile.write(‘                        \‘Length\‘:‘+IntToStr(theF.lengthb)+‘,\n‘)            theFile.write(‘                        \‘Precision\‘:‘+IntToStr(theF.precisionlen)+‘,\n‘)            theFile.write(‘                        \‘Scale\‘:‘+IntToStr(theF.scalelen)+‘\n‘)            theFile.write(‘                        }\n‘)        theFile.write(‘                }\n‘)        theFile.write(‘    KeyField =\‘‘+theKeyField+‘\‘\n‘)        theFile.write(‘    Fields =[‘+theFlds+‘]\n‘)      finally:    theFile.close()    

#這個類用於擷取對象的自訂屬性。

import inspectimport typesclass ObjOpt:    @staticmethod    def IsProperty(obj):        if(obj.__class__ is types.FunctionType):            return False        else:            return True    @staticmethod    def GetPropertyNames(obj):        theAttrs = inspect.getmembers(obj,ObjOpt.IsProperty)        theRetAttrs = []        for attr in theAttrs:            bb=attr[0].startswith(‘__‘)            if bb==False:                theRetAttrs.append(attr[0])        return theRetAttrs;    #擷取類名    @staticmethod    def GetClassName(Obj):        return Obj.__name__

這是一個自動產生的實體類例子：

class M_SS01_SYS_USR(EntityBase.EntityB):    def __init__(self):        M_SS01_SYS_USR.Count += 1        self.RefDict={}        self.CurrFields=[]    Count=0    TableName =‘SS01_SYS_USR‘    KeyField=‘USR_ID‘    Fields=[‘USR_ID‘,‘USR_NAME‘,‘USR_PWD‘]    FieldParams={‘USR_ID‘:                 {                     ‘DSFmt‘:‘%s‘,                     ‘DataType‘:‘varchar‘,                     ‘Length‘:50,                     ‘Precision‘:0,                     ‘Scale‘:0                 },                 ‘USR_NAME‘:                 {                   ‘DSFmt‘:‘%s‘,                   ‘DataType‘:‘varchar‘,                     ‘Length‘:50,                     ‘Precision‘:0,                     ‘Scale‘:0                 },                 ‘USR_PWD‘:                 {                     ‘DSFmt‘:‘%s‘,                     ‘DataType‘:‘varchar‘,                     ‘Length‘:50,                     ‘Precision‘:0,                     ‘Scale‘:0                 }                 }

一個簡單的python MVC架構(1)