/*
 * [The "BSD license"]
 *  Copyright (c) 2011 Terence Parr
 *  All rights reserved.
 *
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 *  modification, are permitted provided that the following conditions
 *  are met:
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
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 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 */

package org.stringtemplate.v4.misc;

import java.util.HashMap;

An automatically created aggregate of properties.

I often have lists of things that need to be formatted, but the list items are actually pieces of data that are not already in an object. I need ST to do something like:

Ter=3432
Tom=32234
....

using template:

$items:{it.name$=$it.type$}$

This example will call getName() on the objects in items attribute, but what if they aren't objects? I have perhaps two parallel arrays instead of a single array of objects containing two fields. One solution is allow Maps to be handled like properties so that it.name would fail getName() but then see that it's a Map and do it.get("name") instead.

This very clean approach is espoused by some, but the problem is that it's a hole in my separation rules. People can put the logic in the view because you could say: "go get bob's data" in the view:

Bob's Phone: $db.bob.phone$

A view should not be part of the program and hence should never be able to go ask for a specific person's data.

After much thought, I finally decided on a simple solution. I've added setAttribute variants that pass in multiple property values, with the property names specified as part of the name using a special attribute name syntax: "name.{propName1,propName2,...}". This object is a special kind of HashMap that hopefully prevents people from passing a subclass or other variant that they have created as it would be a loophole. Anyway, the AggregateModelAdaptor.getProperty method looks for Aggregate as a special case and does a get instead of getPropertyName.

/** An automatically created aggregate of properties. * * <p>I often have lists of things that need to be formatted, but the list * items are actually pieces of data that are not already in an object. I * need ST to do something like:</p> * <p> * Ter=3432<br> * Tom=32234<br> * ....</p> * <p> * using template:</p> * <p> * {@code $items:{it.name$=$it.type$}$}</p> * <p> * This example will call {@code getName()} on the objects in items attribute, but * what if they aren't objects? I have perhaps two parallel arrays * instead of a single array of objects containing two fields. One * solution is allow {@code Map}s to be handled like properties so that {@code it.name} * would fail {@code getName()} but then see that it's a {@code Map} and do * {@code it.get("name")} instead.</p> * <p> * This very clean approach is espoused by some, but the problem is that * it's a hole in my separation rules. People can put the logic in the * view because you could say: "go get bob's data" in the view:</p> * <p> * Bob's Phone: {@code $db.bob.phone$}</p> * <p> * A view should not be part of the program and hence should never be able * to go ask for a specific person's data.</p> * <p> * After much thought, I finally decided on a simple solution. I've * added setAttribute variants that pass in multiple property values, * with the property names specified as part of the name using a special * attribute name syntax: {@code "name.{propName1,propName2,...}"}. This * object is a special kind of {@code HashMap} that hopefully prevents people * from passing a subclass or other variant that they have created as * it would be a loophole. Anyway, the {@link AggregateModelAdaptor#getProperty} * method looks for {@code Aggregate} as a special case and does a {@link #get} instead * of {@code getPropertyName}.</p> */
public class Aggregate { public HashMap<String, Object> properties = new HashMap<String, Object>();
Allow StringTemplate to add values, but prevent the end user from doing so.
/** Allow StringTemplate to add values, but prevent the end * user from doing so. */
protected void put(String propName, Object propValue) { properties.put(propName, propValue); } public Object get(String propName) { return properties.get(propName); } @Override public String toString() { return properties.toString(); } }