Lookup


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64  
65  /**
66   * [Currently not used.... volunteers to integrate?]
67   *
68   *
69   * can filter its lookup popup according to some conditions. For example: list
70   * only cities within a given state.
71   *
72   *
73   * Some note on the design:
74   *
75   * - modifying getValidValues() to some extend (to allow filtering) would be
76   * great. But I still haven't had a clear picture how things work out. That's
77   * one of the reasons that I came up with this 'surgical operation'.
78   *
79   * - One advantage of this surgical operation is that, extending
80   * functionality of getValidValues will still not able to solve the
81   * 'MultiDBObjects-lookup' problem. So I thought it is necessary to put all
82   * this kind of lookup into one place.
83   *
84   * Talking about conditional lookup, I think that flexibility is most
85   * important. The lookup function should allow user to do ORed-condition
86   * lookup on joined tables and views. My plan is to use the same lookup
87   * interface (API), both in add and search, for all cases mentioned above:
88   * full lookup (no filter), partial lookup (with simple/advanced filtering
89   * condition(s)), and MultiDBObjects lookups. The difference of the HashMap
90   * controls the different behavior.
91   *
92   * @version $Revision: 1.12 $  $Date: 2004/11/18 02:03:30 $
93   * @author  Tong Sun
94   *
95   */
96  
97  // ========================================================= &declare ===
98  
99  package com.jcorporate.expresso.services.controller.dbmaint;
100 
101 import com.jcorporate.expresso.core.controller.session.HTTPPersistentSession;
102 import com.jcorporate.expresso.core.db.DBException;
103 import com.jcorporate.expresso.core.dbobj.DBObject;
104 import com.jcorporate.expresso.core.dbobj.ValidValue;
105 import com.jcorporate.expresso.core.misc.SerializableString;
106 import com.jcorporate.expresso.core.misc.StringUtil;
107 import org.apache.log4j.Logger;
108 
109 import javax.servlet.http.HttpServletRequest  ;
110 import java.io.IOException  ;
111 import java.io.ObjectInputStream  ;
112 import java.io.ObjectOutputStream  ;
113 import java.io.Serializable  ;
114 import java.lang.reflect.Method  ;
115 import java.util.HashMap  ;
116 import java.util.Iterator  ;
117 import java.util.Vector  ;
118 
119 // ======================================================= &class_def ===
120 
121 public class Lookup implements Serializable   {
122 
123     /* the logs */
124     transient private static Logger log = Logger.getLogger(Lookup.class);
125 
126     public static final String   DBF_DBNAME = "dbf_dbname";
127     public static final String   DBF_DBKEY = "dbf_dbkey";
128     public static final String   DBF_DBDESC = "dbf_dbdesc";
129     public static final String   DBF_DB_FILTER_FNAME = "dbf_db_filter_fname";
130     public static final String   DBF_DB_FILTER_VALUE = "dbf_db_filter_value";
131     public static final String   DBF_DB_FILTER_WHERE = "dbf_db_filter_where";
132 
133     public static final String   DBM_ACTION_KEY = "dbm_action";
134     public static final String   DBM_ACTION_SEARCH = "search";
135 
136     protected HashMap   theFilter;
137 
138 
139 // -------------------------------------------------------------- &mf ---
140 // .................................................. member function ...
141     /**
142      * Default Constructor
143      */
144     public Lookup() {
145         super();
146         theFilter = new HashMap  ();
147     }
148 
149 // -------------------------------------------------------------- &mf ---
150 // .................................................. member function ...
151     /**
152      * Get property: theFilter
153      *
154      * @return java.util.HashMap
155      */
156     public HashMap   getTheFilter() {
157         return theFilter;
158     }
159 
160 // -------------------------------------------------------------- &mf ---
161 // .................................................. member function ...
162     /**
163      * Adding simple partial lookup filter.
164      * <p/>
165      * Parameters are: lookup db name, key field name, description
166      * field name, filter field name and filter field value.
167      *
168      * @param dbname          the data context
169      * @param dbkey           The key field name
170      * @param dbdesc          The description field name
171      * @param db_filter_fname The field name to filter against
172      * @param db_filter_value The value field name to filter against
173      */
174     public void setFilter(String   dbname, String   dbkey, String   dbdesc,
175                           String   db_filter_fname, String   db_filter_value) {
176         theFilter.put(DBF_DBNAME, dbname);
177         theFilter.put(DBF_DBKEY, dbkey);
178         theFilter.put(DBF_DBDESC, dbdesc);
179         theFilter.put(DBF_DB_FILTER_FNAME, db_filter_fname);
180         theFilter.put(DBF_DB_FILTER_VALUE, db_filter_value);
181     }
182 
183 // -------------------------------------------------------------- &mf ---
184 // .................................................. member function ...
185     /**
186      * Adding advanced partial lookup filter.
187      * <p/>
188      * Parameters are: lookup db name, key field name, description
189      * field name, filter where clause.
190      *
191      * @param dbname          the data context name
192      * @param dbkey           The key field name
193      * @param dbdesc          Description Field Name
194      * @param db_filter_where the where clause to filter against.
195      */
196     public void setFilter(String   dbname, String   dbkey, String   dbdesc,
197                           String   db_filter_where) {
198         theFilter.put(DBF_DBNAME, dbname);
199         theFilter.put(DBF_DBKEY, dbkey);
200         theFilter.put(DBF_DBDESC, dbdesc);
201         theFilter.put(DBF_DB_FILTER_WHERE, db_filter_where);
202     }
203 
204 // -------------------------------------------------------------- &mf ---
205 // .................................................. member function ...
206 
207     /**
208      * Performs the lookup.
209      * <p/>
210      * The basic idea is pre-setting some session variables, i.e.,
211      * &lt;DBObjectName&gt;_filter_&lt;fieldName&gt;. They are HashMap objects that contain
212      * information such as lookup db name, key field name, description field
213      * name, filter field name and filter field value, etc. It is used by
214      * Lookup.java to return ValidValue pairs.
215      * <p/>
216      * The Lookup.java object will be intelligent enough to handle cases like
217      * full lookup (no filter), partial lookup (with simple/advanced filtering
218      * condition(s)), and MultiDBObjects lookups.
219      *
220      * @param myDBObj   The DBObject to get the lookup Values from.
221      * @param fieldName ?
222      * @param mySession ?
223      * @return a Vector of lookup values
224      */
225     public static Vector   getLookupValues
226             (DBObject myDBObj, String   fieldName, HTTPPersistentSession mySession)
227             throws DBException {
228 
229         Vector   values = null;
230         String   sessionString;
231 
232         //System.err.println("\n*** getLookupValues entered");
233         if (log.isDebugEnabled()) {
234             log.debug("*** getLookupValues entered");
235         }
236 
237         sessionString = myDBObj.getMetaData().getName().replace('.', '_')
238                 + "_filter_" + fieldName;
239         //System.err.println("DB: "+ myDBObj.getDBName()+ "\nName: " + sessionString);
240 
241         HashMap   dbFilter = null;
242         boolean getPersistentAttribute_bug_fixed;
243 
244         getPersistentAttribute_bug_fixed = true;
245         getPersistentAttribute_bug_fixed = false;
246 
247         if (getPersistentAttribute_bug_fixed) {
248             // FIXME: unable to get back the Lookup Javabean!
249             /*
250              * I suspect that there's a minor bug in the 'getPersistentAttribute'
251              * function, because I can use it to retrieve plain JSP session
252              * variables, but not Javabean variables. Both kinds of variables can be
253              * retrieved correctly within JSP, using 'session.getAttribute'. It
254              * seems to me there is a glitch between State.getSession() and
255              * HTTPPersistentSession.getPersistentAttribute(). No javabeans defined
256              * as <jsp:useBean /> in JSP can be retrieved that way. After spending
257              * for over 3 days exploring different ways to do it, I'm now curious
258              * whether anybody has eventually retrieve any javabeans defined in JSP
259              * or not. This bug is beyond my capability to solve. So I'm just
260              * leaving my test code here, until someone can find a
261              * solution. Meanwhile, please define plain JSP session variables.
262              */
263             sessionString += "_";
264             Object   lookup_obj = mySession.getPersistentAttribute(sessionString);
265             Lookup lookup = (Lookup) lookup_obj;
266             dbFilter = lookup.getTheFilter();
267         } else {
268             dbFilter = (HashMap  ) mySession.getPersistentAttribute(sessionString);
269         }
270 
271         //System.err.println("HashMap: " + dbFilter);
272         if (dbFilter == null) {
273             // full lookup (no filter)
274             values = myDBObj.getValidValues(fieldName);
275         } else {
276             // partial lookup (with filtering)
277             // getValidValues according to user provided filter
278             values = new Vector  ();
279 
280             try {
281                 Class   c = Class.forName((String  ) dbFilter.get(DBF_DBNAME));
282                 Object   dbo = c.newInstance();
283 
284                 //System.err.println("DBO: "+ dbo);
285                 // setDBName. CALL it ONLY if it exists in the class.  It
286                 // might not be necessary across contexts.
287                 try {
288                     Class   params[] = {java.lang.String  .class};
289                     Method   m = c.getMethod("setDBName", params);
290                     if (m != null) {
291                         Object   paramValues[] = {myDBObj.getDataContext()};
292                         m.invoke(dbo, paramValues);
293                     }
294                 } catch (NoSuchMethodException   nsme) {
295                     //Do nothing, the method just doesn't exist.
296                 } catch (SecurityException   se) {
297                     throw new DBException("Security Exception trying to call"
298                             + " setDBName in loading lookup object", se);
299                 } catch (java.lang.reflect.InvocationTargetException   ive) {
300                     ive.printStackTrace();
301                     throw new DBException("Error calling setDBName in " +
302                             "loading lookup object", ive.getTargetException());
303                 } catch (IllegalAccessException   ilae) {
304                     //Do nothing, setDBName is not public
305                 }
306 
307                 // Get ValidValues
308                 DBObject dboList = (DBObject) dbo;
309                 DBObject oneRecord = null;
310                 // set user provided filter
311                 String   dbf_key;
312                 String   dbf_val;
313                 //System.err.println("Key: "+ (String)dbFilter.get(DBF_DB_FILTER_FNAME) + "\nVal: " + (String)dbFilter.get(DBF_DB_FILTER_VALUE));
314                 dboList.setField((String  ) dbFilter.get(DBF_DB_FILTER_FNAME),
315                         (String  ) dbFilter.get(DBF_DB_FILTER_VALUE));
316                 dbf_key = (String  ) dbFilter.get(DBF_DBKEY);
317                 dbf_val = (String  ) dbFilter.get(DBF_DBDESC);
318                 //System.err.println("Key: "+ dbf_key + "\nVal: " + dbf_val);
319                 Iterator   ii = dboList.searchAndRetrieveList().iterator();
320                 while (ii.hasNext()) {
321                     oneRecord = (DBObject) ii.next();
322                     values.addElement(new
323                             ValidValue(oneRecord.getField(dbf_key),
324                                     oneRecord.getField(dbf_val)));
325                 }
326             } catch (ClassNotFoundException   cn) {
327                 throw new DBException("Lookup object not found", cn);
328             } catch (InstantiationException   ie) {
329                 throw new DBException("Lookup object cannot be instantiated", ie);
330             } catch (IllegalAccessException   iae) {
331                 throw new DBException("llegal access loading Lookup object", iae);
332             }
333 
334         } // !dbFilter
335 
336         //System.err.println("Values: "+ values);
337         if (values == null) {
338             throw new DBException("Valid values for field "
339                     + fieldName + " from object "
340                     + myDBObj.getMetaData().getName() + " were null");
341         }
342 
343         // Add "All Values" entry if searching
344         sessionString = StringUtil.notNull
345                 ((SerializableString) mySession.getPersistentAttribute(DBM_ACTION_KEY));
346         if (DBM_ACTION_SEARCH.equalsIgnoreCase(sessionString)) {
347             values.add(new ValidValue("", "All Values"));
348         }
349         return values;
350     }
351 
352 // -------------------------------------------------------------- &mf ---
353 // .................................................. member function ...
354 
355     public String   toString() {
356         return theFilter.toString();
357     }
358 
359 // -------------------------------------------------------------- &mf ---
360 // .................................................. member function ...
361 
362     /* ************  Serialization Functions *********************** */
363     private void writeObject(ObjectOutputStream   oos) throws IOException   {
364         oos.defaultWriteObject();
365     }
366 
367     private void readObject(ObjectInputStream   ois) throws IOException  ,
368             ClassNotFoundException   {
369         ois.defaultReadObject();
370     }
371 
372 // -------------------------------------------------------------- &mf ---
373 // .................................................. member function ...
374 
375     /**
376      * Remove lookup session variable.
377      *
378      * @param request The Servlet Request
379      */
380     private void remove(HttpServletRequest   request) {
381         // TODO: how to?
382     }
383 }
384 
385 
386 
387
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