From 52f9e495ae036f78829406cb9b7d6542ac2b0a2c Mon Sep 17 00:00:00 2001
From: Jeremy Ruston <jeremy@osmosoft.com>
Date: Fri, 14 Sep 2012 17:29:17 +0100
Subject: [PATCH] Add ability for link macro to link through a given field

This is a bit of a hack, and a more harmonious way of doing this is
planned
---
 core/modules/macros/link.js | 50 +++++++++++++++++++++----------------
 1 file changed, 29 insertions(+), 21 deletions(-)

diff --git a/core/modules/macros/link.js b/core/modules/macros/link.js
index 1dcde7bcd..83e515da7 100644
--- a/core/modules/macros/link.js
+++ b/core/modules/macros/link.js
@@ -21,6 +21,7 @@ exports.info = {
 	name: "link",
 	params: {
 		to: {byName: "default", type: "tiddler", skinny: true},
+		throughField: {byname: true, type: "text"},
 		space: {byName: true, type: "text"}
 	}
 };
@@ -33,7 +34,7 @@ exports.handleEvent = function (event) {
 		} else {
 			var navEvent = document.createEvent("Event");
 			navEvent.initEvent("tw-navigate",true,true);
-			navEvent.navigateTo = this.params.to;
+			navEvent.navigateTo = this.linkInfo.to;
 			navEvent.navigateFrom = this;
 			event.target.dispatchEvent(navEvent); 
 			event.preventDefault();
@@ -44,42 +45,49 @@ exports.handleEvent = function (event) {
 
 exports.executeMacro = function() {
 	// Assemble the information about the link
-	var linkInfo = {
-		to: this.params.to,
+	this.linkInfo = {
 		space: this.params.space
 	};
-	// Generate the default link characteristics
-	linkInfo.isExternal = isLinkExternal(linkInfo.to);
-	if(!linkInfo.isExternal) {
-		linkInfo.isMissing = !this.wiki.tiddlerExists(linkInfo.to);
+	if(this.hasParameter("to")) {
+		this.linkInfo.to = this.params.to;
+	} else if(this.hasParameter("throughField") && this.tiddlerTitle) {
+		var currTiddler = this.wiki.getTiddler(this.tiddlerTitle);
+		if(currTiddler && this.params.throughField in currTiddler.fields) {
+			this.linkInfo.to = currTiddler.fields[this.params.throughField];
+		}
 	}
-	linkInfo.attributes = {
-		href: linkInfo.to
+	// Generate the default link characteristics
+	this.linkInfo.isExternal = isLinkExternal(this.linkInfo.to);
+	if(!this.linkInfo.isExternal) {
+		this.linkInfo.isMissing = !this.wiki.tiddlerExists(this.linkInfo.to);
+	}
+	this.linkInfo.attributes = {
+		href: this.linkInfo.to
 	};
-	if(!linkInfo.isExternal) {
-		linkInfo.attributes.href = encodeURIComponent(linkInfo.to);
+	if(!this.linkInfo.isExternal) {
+		this.linkInfo.attributes.href = encodeURIComponent(this.linkInfo.to);
 	}
 	// Generate the default classes for the link
-	linkInfo.attributes["class"] = ["tw-tiddlylink"];
-	if(linkInfo.isExternal) {
-		linkInfo.attributes["class"].push("tw-tiddlylink-external");
+	this.linkInfo.attributes["class"] = ["tw-tiddlylink"];
+	if(this.linkInfo.isExternal) {
+		this.linkInfo.attributes["class"].push("tw-tiddlylink-external");
 	} else {
-		linkInfo.attributes["class"].push("tw-tiddlylink-internal");
-		if(linkInfo.isMissing) {
-			linkInfo.attributes["class"].push("tw-tiddlylink-missing");
+		this.linkInfo.attributes["class"].push("tw-tiddlylink-internal");
+		if(this.linkInfo.isMissing) {
+			this.linkInfo.attributes["class"].push("tw-tiddlylink-missing");
 		} else {
-			linkInfo.attributes["class"].push("tw-tiddlylink-resolves");
+			this.linkInfo.attributes["class"].push("tw-tiddlylink-resolves");
 		}
 	}
 	if(this.classes) {
-		$tw.utils.pushTop(linkInfo.attributes["class"],this.classes);
+		$tw.utils.pushTop(this.linkInfo.attributes["class"],this.classes);
 	}
 	// Create the link
 	var child;
-	if(linkInfo.suppressLink) {
+	if(this.linkInfo.suppressLink) {
 		child = $tw.Tree.Element("span",{},this.content);
 	} else { 
-		child = $tw.Tree.Element("a",linkInfo.attributes,this.content,{events: ["click"], eventHandler: this});
+		child = $tw.Tree.Element("a",this.linkInfo.attributes,this.content,{events: ["click"], eventHandler: this});
 	}
 	child.execute(this.parents,this.tiddlerTitle);
 	return child;