请教关于uesr exit的用途

xiaoerp

SAP提供了UESR EXIT 功能，不知道到底是什么作用呢？
user exit (one kind of enhancement,程序增强),只要是SAP提供的user exit,咱这基本都用上了.简单的说,就是SAP 留给你做功能增强用的.
用户增强: 所有的Enhancement在表MODSAP,用户增强大概有三类

MODSAP是Enhancement表, 而TFDIR是看是否此enhancement被激活,就看字段MAND是否是”C”而已

1.       E Enhancement exits :就是常说的写User_exit

2.       C GUI codes

3.        S Subscreens 屏幕增强 (比如ME21n create PO加些字段)

xiaoerp

举一个简单的例子,其实SAP是有帮助的. 知道condition 吧,condition多种用途,比如MM,SD的pricing,定价,FI tax IMG,还有很多比如...,其实condition也是非常容易的,有时间将它整理出来share一下.



从理论上讲,就说MM模块,可随便采用EKKO,EKPO,shipping,route等什么乱七八糟的表的相关字段做condition,但是SAP又没提供相关功能,就需要增强.  比如收货时如果material  price = 0就不允许收货,这些SAP没有提供相关支持就自己搞定,这就是增强.Understand ?

System Enhancements
If you have extended the field catalog to include your own fields, you must make the relevant fields accessible in the Purchasing transactions.
This section describes how to proceed.

Communication structures
The following communication structures are relevant to pricing:


KOMK  (Price determination communication header)
KOMP  (Price determination communication item)
KOMG  (Allowed fields for condition structures)

For technical reasons, the communication structure KOMG is used. This represents the total of KOMK and KOMP and contains all fields that can basically be used for price determination purposes. The inclusion of new fields in KOMK or KOMP automatically means that they are also included in KOMG.

INCLUDES
Fields for price determination are contained in the following INCLUDES:


Header data in KOMKAZ (INCLUDE in KOMK/KOMG)
Item data in KOMPAZ (INCLUDE in KOMP/KOMG)

USER EXITS
The new fields in the processing of purchasing documents are filled with the following USER EXITS:


Extension of LMEKO001 with function module EXIT_SAPLMEKO_001
(for the header fields of table KOMK)

Extension of LMEKO002 with function module EXIT_SAPLMEKO_002
(for the item fields of table KOMP)

You must activate the USER EXITS with transaction CMOD.

Example

The example describes how to proceed in order to use the document field EKGRP (purchasing group) for price determination (in the standard system it is not defined for this purpose).

1. First check whether there is a corresponding document field in the standard system.
The purchasing group (= field EKGRP) is found in purchasing documents at header level.
2. Check whether a header or item field is involved.
Field EKGRP is stored in table EKKO and is therefore a header field.
3. Include the field name ZZEKGRP in the communication structure KOMK (via the INCLUDE KOMKAZ) and assign the data element EKGRP to it.
Note that new data fields must begin with the letters "ZZ" or "YY", because SAP keeps these name slots free in the standard system to protect them from being overwritten at the time of Release changeovers.
4. Activate the structure.
This causes those structures in which this INCLUDE structure is integrated also to be generated.
5. Populate the new field in program ZXM06U14, which is used in the
function module EXIT_SAPLMEKO_001, as follows:

MOVE I_KOMK TO E_KOMK.
MOVE I_EKKO-EKGRP TO E_KOMK-EKGRP.