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Java > Open Source Codes > org > apache > cayenne > access > trans > UpdateTranslator


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19
20 package org.apache.cayenne.access.trans;
21
22 import java.util.Iterator JavaDoc;
23 import java.util.Map JavaDoc;
24
25 import org.apache.cayenne.CayenneRuntimeException;
26 import org.apache.cayenne.map.DbAttribute;
27 import org.apache.cayenne.map.DbEntity;
28 import org.apache.cayenne.map.DbRelationship;
29 import org.apache.cayenne.query.UpdateQuery;
30
31 /** Class implements default translation mechanism of
32   * org.apache.cayenne.query.UpdateQuery
33   * objects to SQL UPDATE statements.
34   *
35   * @author Andrus Adamchik
36   */
37 public class UpdateTranslator extends QueryAssembler {
38
39     public String JavaDoc aliasForTable(DbEntity dbEnt) {
40         throw new RuntimeException JavaDoc("aliases not supported");
41     }
42
43     public void dbRelationshipAdded(DbRelationship dbRel) {
44         throw new RuntimeException JavaDoc("db relationships not supported");
45     }
46
47     /** Method that converts an update query into SQL string */
48     public String JavaDoc createSqlString() throws Exception JavaDoc {
49         StringBuffer JavaDoc queryBuf = new StringBuffer JavaDoc();
50         queryBuf.append("UPDATE ");
51
52         // 1. append table name
53 DbEntity dbEnt = getRootEntity().getDbEntity();
54         queryBuf.append(dbEnt.getFullyQualifiedName());
55
56         // 2. build "set ..." clause
57 buildSetClause(queryBuf, (UpdateQuery) query);
58
59         // 3. build qualifier
60 String JavaDoc qualifierStr =
61             adapter.getQualifierTranslator(this).doTranslation();
62         if (qualifierStr != null)
63             queryBuf.append(" WHERE ").append(qualifierStr);
64
65         return queryBuf.toString();
66     }
67
68     /** Translate updated values and relationships into
69      * "SET ATTR1 = Val1, ..." SQL statement.
70      */
71     private void buildSetClause(StringBuffer JavaDoc queryBuf, UpdateQuery query) {
72         Map JavaDoc updAttrs = query.getUpdAttributes();
73         // set of keys.. each key is supposed to be ObjAttribute
74 Iterator JavaDoc attrIt = updAttrs.entrySet().iterator();
75
76         if (!attrIt.hasNext())
77             throw new CayenneRuntimeException("Nothing to update.");
78
79         DbEntity dbEnt = getRootEntity().getDbEntity();
80         queryBuf.append(" SET ");
81
82         // append updated attribute values
83 boolean appendedSomething = false;
84
85         // now process other attrs in the loop
86 while (attrIt.hasNext()) {
87             Map.Entry JavaDoc entry = (Map.Entry JavaDoc) attrIt.next();
88             String JavaDoc nextKey = (String JavaDoc) entry.getKey();
89             Object JavaDoc attrVal = entry.getValue();
90
91             if (appendedSomething)
92                 queryBuf.append(", ");
93
94             queryBuf.append(nextKey).append(" = ?");
95             super.addToParamList(
96                 (DbAttribute) dbEnt.getAttribute(nextKey),
97                 attrVal);
98             appendedSomething = true;
99         }
100     }
101 }
102
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