From 763f8afaf2dc7dcaa2d4a492887a944d84c4fed2 Mon Sep 17 00:00:00 2001
From: Jermolene <jeremy@jermolene.com>
Date: Wed, 15 Aug 2018 13:50:07 +0100
Subject: [PATCH] Add "contains" filter operator for searching list fields

---
 core/modules/filters/contains.js              | 45 +++++++++++++++++++
 core/modules/tiddler.js                       | 12 +++++
 .../tiddlers/filters/contains Operator.tid    | 16 +++++++
 .../examples/contains Operator (Examples).tid |  8 ++++
 4 files changed, 81 insertions(+)
 create mode 100644 core/modules/filters/contains.js
 create mode 100644 editions/tw5.com/tiddlers/filters/contains Operator.tid
 create mode 100644 editions/tw5.com/tiddlers/filters/examples/contains Operator (Examples).tid

diff --git a/core/modules/filters/contains.js b/core/modules/filters/contains.js
new file mode 100644
index 000000000..964c6700f
--- /dev/null
+++ b/core/modules/filters/contains.js
@@ -0,0 +1,45 @@
+/*\
+title: $:/core/modules/filters/contains.js
+type: application/javascript
+module-type: filteroperator
+
+Filter operator for finding values in array fields
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+/*
+Export our filter function
+*/
+exports.contains = function(source,operator,options) {
+	var results = [],
+		fieldname = (operator.suffix || "list").toLowerCase();
+	if(operator.prefix === "!") {
+		source(function(tiddler,title) {
+			if(tiddler) {
+				var list = tiddler.getFieldList(fieldname);
+				if(list.indexOf(operator.operand) === -1) {
+					results.push(title);
+				}
+			} else {
+				results.push(title);
+			}
+		});
+	} else {
+		source(function(tiddler,title) {
+			if(tiddler) {
+				var list = tiddler.getFieldList(fieldname);
+				if(list.indexOf(operator.operand) !== -1) {
+					results.push(title);
+				}
+			}
+		});
+	}
+	return results;
+};
+
+})();
diff --git a/core/modules/tiddler.js b/core/modules/tiddler.js
index e3382af4a..efec78b5c 100644
--- a/core/modules/tiddler.js
+++ b/core/modules/tiddler.js
@@ -39,6 +39,18 @@ exports.getFieldString = function(field) {
 	}
 };
 
+/*
+Get the value of a field as a list
+*/
+exports.getFieldList = function(field) {
+	var value = this.fields[field];
+	// Check for a missing field
+	if(value === undefined || value === null) {
+		return [];
+	}
+	return $tw.utils.parseStringArray(value);
+};
+
 /*
 Get all the fields as a hashmap of strings. Options:
 	exclude: an array of field names to exclude
diff --git a/editions/tw5.com/tiddlers/filters/contains Operator.tid b/editions/tw5.com/tiddlers/filters/contains Operator.tid
new file mode 100644
index 000000000..608d22def
--- /dev/null
+++ b/editions/tw5.com/tiddlers/filters/contains Operator.tid	
@@ -0,0 +1,16 @@
+caption: contains
+created: 20180815124349784
+modified: 20180815124607101
+op-input: a [[selection of titles|Title Selection]]
+op-neg-output: those input tiddlers in which the list field <<.place F>> does <<.em not>> contain the value <<.place S>>
+op-output: those input tiddlers in which the list field <<.place F>> contains the value <<.place S>>
+op-parameter: a possible value to be found in list field <<.place F>>
+op-parameter-name: S
+op-purpose: filter the input by searching list fields for a value
+op-suffix: the name of a [[field|TiddlerFields]]
+op-suffix-name: F
+tags: [[Filter Operators]] [[Field Operators]] [[Negatable Operators]]
+title: contains Operator
+type: text/vnd.tiddlywiki
+
+<<.operator-examples "contains">>
diff --git a/editions/tw5.com/tiddlers/filters/examples/contains Operator (Examples).tid b/editions/tw5.com/tiddlers/filters/examples/contains Operator (Examples).tid
new file mode 100644
index 000000000..9140068fc
--- /dev/null
+++ b/editions/tw5.com/tiddlers/filters/examples/contains Operator (Examples).tid	
@@ -0,0 +1,8 @@
+created: 20180815124630157
+modified: 20180815124919662
+tags: [[contains Operator]] [[Operator Examples]]
+title: contains Operator (Examples)
+type: text/vnd.tiddlywiki
+
+<<.operator-example 1 "[contains:tags[HelloThere]]" "equivalent to [tag[HelloThere]]">>
+<<.operator-example 2 "[[$:/StoryList]contains[HelloThere]]" "checks whether the tiddler 'HelloThere' is currently displayed in the story river">>