extend lookup op flexibility with 2 parameters (#5315)

core/modules/filters/lookup.js

@@ -5,9 +5,11 @@ module-type: filteroperator
 
 Filter operator that looks up values via a title prefix
 
-[lookup:<field>[<prefix>]]
+[lookup:<defaultvalue>:<field OR index>[<prefix>],[<field-name OR index-name>]]
 
-Prepends the prefix to the selected items and returns the specified field value
+Prepends the prefix to the selected items and returns the specified 
+field or index value. If the 2nd suffix does not exist, it defaults to field.
+If the second operand is missing it defaults to "text" for fields, and "0" for indexes
 
 \*/
 (function(){
@@ -20,10 +22,35 @@ Prepends the prefix to the selected items and returns the specified field value
 Export our filter function
 */
 exports.lookup = function(source,operator,options) {
-	var results = [];
-	source(function(tiddler,title) {
-		results.push(options.wiki.getTiddlerText(operator.operand + title) || operator.suffix || '');
-	});
+	var results = [],
+		suffixes = operator.suffixes || [],
+		defaultSuffix = suffixes[0] ? (suffixes[0][0] || "") : "",
+		indexSuffix = (suffixes[1] && suffixes[1][0] === "index") ? true : false,
+		target;
+	if(operator.operands.length == 2) {
+		target = operator.operands[1]
+	} else {
+		target = indexSuffix ? "0": "text";
+	}
+	if(indexSuffix) {
+		source(function(tiddler,title) {
+			var targetTitle = operator.operands[0] + title;
+			var data = options.wiki.extractTiddlerDataItem(targetTitle,target,defaultSuffix);
+			results.push(data);
+		});
+	} else {
+		source(function(tiddler,title) {
+			var targetTitle = operator.operands[0] + title;
+			var targetTiddler = options.wiki.getTiddler(targetTitle);
+			if(targetTiddler) {
+				var value = targetTiddler.getFieldString(target);
+				if(value == "" && defaultSuffix !== "") {
+					value = defaultSuffix;
+				}
+				results.push(value);
+			}
+		});
+	}
 	return results;
 };
 

editions/tw5.com/tiddlers/filters/examples/lookup Operator (Examples).tid

@@ -1,7 +1,10 @@
 created: 20170907144257037
-modified: 20170907144559822
+modified: 20201224034837935
 title: lookup Operator (Examples)
 type: text/vnd.tiddlywiki
 
 <<.operator-example 1 "[all[shadows+tiddlers]tag[$:/tags/PageControls]lookup[$:/config/PageControlButtons/Visibility/]]" "Retrieve the visibility status of each page control button">>
 <<.operator-example 2 "[all[shadows+tiddlers]tag[$:/tags/PageControls]lookup:show[$:/config/PageControlButtons/Visibility/]]" "Retrieve the visibility status of each page control button, this time with a default value">>
+<<.operator-example 3 "[all[tiddlers]has[plugin-type]removeprefix[$:/plugins/tiddlywiki/]lookup:missing-description:field[$:/plugins/tiddlywiki/],[description]]" "Retrieve the description of all plugin-tiddlers that are in the `$:/plugins/tiddlywiki/` namespace.">>
+<<.operator-example 4 "OriginalTiddlerPaths +[lookup:missing-index:index[$:/config/],[HelloThere]]" "Lookup the original tiddler path on disk for the [[Hello There]] tiddler.">>
+<<.operator-example 5 "OriginalTiddlerPaths +[lookup:missing-index:index[$:/config/],[MissingTiddler]]" "Lookup the original tiddler path on disk for the [[MissingTiddler]] tiddler.">>

editions/tw5.com/tiddlers/filters/lookup Operator.tid

@@ -1,24 +1,40 @@
 caption: lookup
 created: 20170907103639431
-modified: 20170907144703051
+modified: 20210116081305739
 op-input: a [[selection of titles|Title Selection]]
-op-output: the lookup values corresponding to each input title
-op-parameter: prefix applied to input titles to yield title of lookup tiddler from which value is retrieved
-op-parameter-name: P
-op-purpose: applies a prefix to each input title to yield the title of a tiddler from which the final value is retrieved
-op-suffix: the default value to be used for missing lookups
-op-suffix-name: D
+op-output: the lookup values corresponding to each lookup tiddler
+op-parameter: prefix applied to input titles to yield title of lookup tiddler from which value is retrieved. Now accepts 1 or 2 parameters, see below for details
+op-parameter-name: P, T
+op-purpose: applies a prefix to each input title to yield the title of a tiddler from which the final value is retrieved. With a single parameter, the default field is "text" and the default index is "0". If a second parameter is provided, that becomes the target field or index.
+op-suffix: the default value to be used for missing lookups. This operator can now accept a second suffix, see below for details
+op-suffix-name: D, I
 tags: [[Filter Operators]]
 title: lookup Operator
 type: text/vnd.tiddlywiki
 
 <<.from-version "5.1.15">>
 
-The action of this operator is as follows:
+The action of this operator is as follows with 1 parameter:
 
 * Apply the specified prefix to each input tiddler title, yielding a new list of tiddler titles
-* Transclude the value of each of those tiddlers
-** Substitute the default value for missing or empty tiddlers
+* Transclude the value of the `text` field each of those tiddlers
+** Substitute the default value for missing or empty values
+* Return the list of values
+
+<<.from-version "5.1.24">>
+
+The action of this operator is as follows with 2 parameters:
+
+If there are two parameters provided, use the second parameter as the target field or index.
+
+<<.note """If there is only one parameter given, the filter checks for a second suffix equal to "index". If this suffix is found, the default target index is "0".
+In all other cases, the default target field is "text".""">>
+
+Then:
+
+* Apply the specified prefix to each input tiddler title, yielding a new list of tiddler titles
+* Transclude the value of the target field or index
+** Substitute the default value for missing or empty values
 * Return the list of values
 
 <<.operator-examples "lookup">>