Thread: JDBC - DatabaseMetaData.getTables() null pointer exception
Dave Antal (dantal@vigilos.com) reports a bug with a severity of 2
The lower the number the more severe it is.
Short Description
JDBC - DatabaseMetaData.getTables() null pointer exception
Long Description
When you pass the DatabaseMetaData.getTables() method a types array that contains "VIEW" a null pointer exception is
generated.This is in the JDBC driver that is with Postgres 7.1.2. This is caused by the code not checking for a View
typeon the relkind column returned from the select of pg_class. The code example below contains a version of the method
witha fix in place.
Sample Code
/**
* Get a description of tables available in a catalog.
*
* <p>Only table descriptions matching the catalog, schema, table
* name and type criteria are returned. They are ordered by
* TABLE_TYPE, TABLE_SCHEM and TABLE_NAME.
*
* <p>Each table description has the following columns:
*
* <ol>
* <li><b>TABLE_CAT</b> String => table catalog (may be null)
* <li><b>TABLE_SCHEM</b> String => table schema (may be null)
* <li><b>TABLE_NAME</b> String => table name
* <li><b>TABLE_TYPE</b> String => table type. Typical types are "TABLE",
* "VIEW", "SYSTEM TABLE", "GLOBAL TEMPORARY", "LOCAL
* TEMPORARY", "ALIAS", "SYNONYM".
* <li><b>REMARKS</b> String => explanatory comment on the table
* </ol>
*
* <p>The valid values for the types parameter are:
* "TABLE", "INDEX", "SEQUENCE", "SYSTEM TABLE" and "SYSTEM INDEX"
*
* @param catalog a catalog name; For org.postgresql, this is ignored, and
* should be set to null
* @param schemaPattern a schema name pattern; For org.postgresql, this is ignored, and
* should be set to null
* @param tableNamePattern a table name pattern. For all tables this should be "%"
* @param types a list of table types to include; null returns
* all types
* @return each row is a table description
* @exception SQLException if a database-access error occurs.
*/
public java.sql.ResultSet getTables(String catalog, String schemaPattern, String tableNamePattern, String types[])
throwsSQLException
{
// Handle default value for types
if(types==null)
types = defaultTableTypes;
if(tableNamePattern==null)
tableNamePattern="%";
// the field descriptors for the new ResultSet
Field f[] = new Field[5];
java.sql.ResultSet r; // ResultSet for the SQL query that we need to do
Vector v = new Vector(); // The new ResultSet tuple stuff
f[0] = new Field(connection, "TABLE_CAT", iVarcharOid, 32);
f[1] = new Field(connection, "TABLE_SCHEM", iVarcharOid, 32);
f[2] = new Field(connection, "TABLE_NAME", iVarcharOid, 32);
f[3] = new Field(connection, "TABLE_TYPE", iVarcharOid, 32);
f[4] = new Field(connection, "REMARKS", iVarcharOid, 32);
// Now form the query
StringBuffer sql = new StringBuffer("select relname,oid,relkind from pg_class where (");
boolean notFirst=false;
for(int i=0;i<types.length;i++) {
for(int j=0;j<getTableTypes.length;j++)
if(getTableTypes[j][0].equals(types[i])) {
if(notFirst)
sql.append(" or ");
sql.append(getTableTypes[j][1]);
notFirst=true;
}
}
// Added by Stefan Andreasen <stefan@linux.kapow.dk>
// Now take the pattern into account
sql.append(") and relname like '");
sql.append(tableNamePattern.toLowerCase());
sql.append("'");
// Now run the query
r = connection.ExecSQL(sql.toString());
byte remarks[];
while (r.next())
{
byte[][] tuple = new byte[5][0];
// Fetch the description for the table (if any)
java.sql.ResultSet dr = connection.ExecSQL("select description from pg_description where objoid="+r.getInt(2));
if(((org.postgresql.ResultSet)dr).getTupleCount()==1) {
dr.next();
remarks = dr.getBytes(1);
} else
remarks = defaultRemarks;
dr.close();
String relKind;
switch (r.getBytes(3)[0]) {
case 'r':
relKind = "TABLE";
break;
case 'i':
relKind = "INDEX";
break;
case 'S':
relKind = "SEQUENCE";
break;
case 'v':
relKind = "VIEW";
break;
default:
relKind = null;
}
tuple[0] = null; // Catalog name
tuple[1] = null; // Schema name
tuple[2] = r.getBytes(1); // Table name
tuple[3] = relKind.getBytes(); // Table type
tuple[4] = remarks; // Remarks
v.addElement(tuple);
}
r.close();
return new ResultSet(connection, f, v, "OK", 1);
}
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Download newer version at:
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This bug is fixed.
> Dave Antal (dantal@vigilos.com) reports a bug with a severity of 2
> The lower the number the more severe it is.
>
> Short Description
> JDBC - DatabaseMetaData.getTables() null pointer exception
>
> Long Description
> When you pass the DatabaseMetaData.getTables() method a types array that contains "VIEW" a null pointer exception is
generated.This is in the JDBC driver that is with Postgres 7.1.2. This is caused by the code not checking for a View
typeon the relkind column returned from the select of pg_class. The code example below contains a version of the method
witha fix in place.
>
> Sample Code
> /**
> * Get a description of tables available in a catalog.
> *
> * <p>Only table descriptions matching the catalog, schema, table
> * name and type criteria are returned. They are ordered by
> * TABLE_TYPE, TABLE_SCHEM and TABLE_NAME.
> *
> * <p>Each table description has the following columns:
> *
> * <ol>
> * <li><b>TABLE_CAT</b> String => table catalog (may be null)
> * <li><b>TABLE_SCHEM</b> String => table schema (may be null)
> * <li><b>TABLE_NAME</b> String => table name
> * <li><b>TABLE_TYPE</b> String => table type. Typical types are "TABLE",
> * "VIEW", "SYSTEM TABLE", "GLOBAL TEMPORARY", "LOCAL
> * TEMPORARY", "ALIAS", "SYNONYM".
> * <li><b>REMARKS</b> String => explanatory comment on the table
> * </ol>
> *
> * <p>The valid values for the types parameter are:
> * "TABLE", "INDEX", "SEQUENCE", "SYSTEM TABLE" and "SYSTEM INDEX"
> *
> * @param catalog a catalog name; For org.postgresql, this is ignored, and
> * should be set to null
> * @param schemaPattern a schema name pattern; For org.postgresql, this is ignored, and
> * should be set to null
> * @param tableNamePattern a table name pattern. For all tables this should be "%"
> * @param types a list of table types to include; null returns
> * all types
> * @return each row is a table description
> * @exception SQLException if a database-access error occurs.
> */
> public java.sql.ResultSet getTables(String catalog, String schemaPattern, String tableNamePattern, String types[])
throwsSQLException
> {
> // Handle default value for types
> if(types==null)
> types = defaultTableTypes;
>
> if(tableNamePattern==null)
> tableNamePattern="%";
>
> // the field descriptors for the new ResultSet
> Field f[] = new Field[5];
> java.sql.ResultSet r; // ResultSet for the SQL query that we need to do
> Vector v = new Vector(); // The new ResultSet tuple stuff
>
> f[0] = new Field(connection, "TABLE_CAT", iVarcharOid, 32);
> f[1] = new Field(connection, "TABLE_SCHEM", iVarcharOid, 32);
> f[2] = new Field(connection, "TABLE_NAME", iVarcharOid, 32);
> f[3] = new Field(connection, "TABLE_TYPE", iVarcharOid, 32);
> f[4] = new Field(connection, "REMARKS", iVarcharOid, 32);
>
> // Now form the query
> StringBuffer sql = new StringBuffer("select relname,oid,relkind from pg_class where (");
> boolean notFirst=false;
> for(int i=0;i<types.length;i++) {
> for(int j=0;j<getTableTypes.length;j++)
> if(getTableTypes[j][0].equals(types[i])) {
> if(notFirst)
> sql.append(" or ");
> sql.append(getTableTypes[j][1]);
> notFirst=true;
> }
> }
>
> // Added by Stefan Andreasen <stefan@linux.kapow.dk>
> // Now take the pattern into account
> sql.append(") and relname like '");
> sql.append(tableNamePattern.toLowerCase());
> sql.append("'");
>
> // Now run the query
> r = connection.ExecSQL(sql.toString());
>
> byte remarks[];
>
> while (r.next())
> {
> byte[][] tuple = new byte[5][0];
>
> // Fetch the description for the table (if any)
> java.sql.ResultSet dr = connection.ExecSQL("select description from pg_description where objoid="+r.getInt(2));
> if(((org.postgresql.ResultSet)dr).getTupleCount()==1) {
> dr.next();
> remarks = dr.getBytes(1);
> } else
> remarks = defaultRemarks;
> dr.close();
>
> String relKind;
> switch (r.getBytes(3)[0]) {
> case 'r':
> relKind = "TABLE";
> break;
> case 'i':
> relKind = "INDEX";
> break;
> case 'S':
> relKind = "SEQUENCE";
> break;
> case 'v':
> relKind = "VIEW";
> break;
> default:
> relKind = null;
> }
>
> tuple[0] = null; // Catalog name
> tuple[1] = null; // Schema name
> tuple[2] = r.getBytes(1); // Table name
> tuple[3] = relKind.getBytes(); // Table type
> tuple[4] = remarks; // Remarks
> v.addElement(tuple);
> }
> r.close();
> return new ResultSet(connection, f, v, "OK", 1);
> }
>
> No file was uploaded with this report
>
>
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