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https://issues.apache.org/jira/browse/VELOCITY-814?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Nathan Bubna resolved VELOCITY-814.
-----------------------------------
Resolution: Fixed
Fix Version/s: (was: 1.7.x)
2.x
Sorry it took so long. Holidays and all...
I applied the patch to 2.x, as that is the trunk now and likely next version.
> Allow for overriding the query used by DataSourceResourceLoader
> ---------------------------------------------------------------
>
> Key: VELOCITY-814
> URL: https://issues.apache.org/jira/browse/VELOCITY-814
> Project: Velocity
> Issue Type: Improvement
> Components: Engine
> Affects Versions: 1.7.x
> Reporter: Darren Cruse
> Priority: Minor
> Labels: patch
> Fix For: 2.x
>
> Attachments: DataSourceResourceLoader.java
>
> Original Estimate: 1h
> Remaining Estimate: 1h
>
> In future versions of Velocity 1.7, allow users of DataSourceResourceLoader
> to customize the database query used by extending the class and overriding
> the getStatement() method.
> This would be helpful for users in cases where the table being accessed is
> pre-existing and has a structure that does not match the default query. e.g.
> The default query does not work if the table has a compound key rather than a
> single column key.
> This feature is also helpful if the template name passed by velocity differs
> from what is actually stored in their table's keys - by overriding
> getStatement() they can parse the template name passed prior to the query
> being run to deal with such differences.
> Without this change such users will likely copy and modify the entire
> DataSourceResourceLoader.java file, but with this change it's far easier to
> simply override the getStatement() function alone.
> The necessary changes are simply to:
> a. make the getStatement() function protected not private, and
> b. pass in tableName and keyColumn so the function doesn't need access those
> as private members.
> i.e. the getStatement() function becomes as follows:
> /**
> * Creates the following PreparedStatement query :
> * <br>
> * SELECT columnNames FROM tableName WHERE keyColumn
> * = 'templateName'
> * <br>
> * where keyColumn is a class member set in init()
> *
> * @param conn connection to datasource
> * @param columnNames columns to fetch from datasource
> * @param tableName table to fetch from
> * @param keyColumn column whose value should match templateName
> * @param templateName name of template to fetch
> * @return PreparedStatement
> */
> protected PreparedStatement getStatement(final Connection conn,
> final String columnNames,
> final String tableName,
> final String keyColumn,
> final String templateName) throws SQLException
> {
> PreparedStatement ps = conn.prepareStatement("SELECT " + columnNames
> + " FROM "+ tableName + " WHERE " + keyColumn + " = ?");
> ps.setString(1, templateName);
> return ps;
> }
> And then the two calls to getStatement() are changed to pass the tableName
> and keyColumn name as parameters:
> 1. The call to getStatement() at line 232 changes from:
> ps = getStatement(conn, templateColumn, name);
> to:
> ps = getStatement(conn, templateColumn, tableName, keyColumn,
> name);
> 2. The call to getStatement() at line 308 changes from:
> ps = getStatement(conn, timestampColumn, name);
> to:
> ps = getStatement(conn, timestampColumn, tableName, keyColumn,
> name);
> The changed and tested Velocity 1.7 DataSourceResourceLoader.java is attached.
> This JIRA was originally discussed in the Velocity Old Nabble forum message
> at:
>
> http://old.nabble.com/Customizing-the-query-used-by-DataSourceResourceLoader-to32957497.html
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