Add option for static default value for the transform URL

Author: Alkarex

README.md

@@ -173,7 +173,8 @@ Output:
 * *Context*: Node-RED node, or command line with `node ./index.js multi-schema-transformer`
 * *Purpose*: Ability to transform a JSON observation on the fly from whichever format to another format (e.g. one of the FIWARE NGSI types) using a specified JSONata URL. Schemas are automatically downloaded and cached the first time they are needed.
 * *Input*: A JSON observation in whichever format in the `msg.payload` property, and the corresponding JSONata URL on the `msg.schemaUrl` property (coming from json-multi-schema-resolver).
-  * If no `msg.schemaUrl` is provided, no transformation is performed.
+  * Alternatively, a static default value for the schema URL can be set in the corresponding property.
+  * If no `msg.schemaUrl` is provided, and no value set in the default schema URL property, then no transformation is performed.
 * *Output*: The transformed JSON observation in the `msg.payload` property, the used JSONata in the `msg.transformUrl` (if any transformation was performed), and potential validation errors in the `msg.error` property.
 * *Implementation*: Based on [JSONata](https://github.com/jsonata-js/jsonata).
 
@@ -238,6 +239,14 @@ node ./index.js json-multi-schema-transformer | \
 jq .
 ```
 
+Same example, but using a static default value for the schema URL in the corresponding property:
+
+```
+echo '{"payload":{"id":"TA120-T246177","type":"Cesva-TA120","NoiseLevelObserved":{"id":"TA120-T246177-NoiseLevelObserved-2018-09-17T07:01:09.000000Z","sonometerClass":"1","location":{"coordinates":[24.985891,60.274286],"type":"Point"},"measurand":["LAeq | 48.6 | A-weighted, equivalent, sound level"],"dateObserved":"2018-09-17T07:01:09.000000Z","LAeq":48.6,"type":"NoiseLevelObserved"}},"error":false}' | \
+node ./index.js json-multi-schema-transformer --defaultSchemaUrl='"https://raw.githubusercontent.com/alexandrainst/node-red-contrib-json-multi-schema/master/examples/Cesva-TA120-to-NoiseLevelObserved.jsonata.js"' | \
+jq .
+```
+
 Output:
 
 ```json

json-multi-schema-transformer.html

@@ -4,6 +4,7 @@
 		color: '#00B4FF',
 		defaults: {
 			name: { value: '', },
+			defaultSchemaUrl: { value: '', },
 		},
 		inputs: 1,
 		outputs: 1,
@@ -19,12 +20,18 @@
 		<label for="node-input-name"><i class="icon-tag"></i> Name</label>
 		<input type="text" id="node-input-name" placeholder="Name" />
 	</div>
+
+	<div class="form-row">
+		<label for="node-input-defaultSchemaUrl"><i class="icon-tag"></i> Default Schema URL</label>
+		<input type="text" id="node-input-defaultSchemaUrl" placeholder="defaultSchemaUrl" />
+	</div>
 </script>
 
 <script type="text/x-red" data-help-name="json-multi-schema-transformer">
 	<p>Node to transform a JSON observation to another format using a configurable set of JSONata rules.</p>
 	<ul>
-		<li>The node will transform a given JSON payload received in <code>msg.payload</code> using some JSONata rules, which URL is given in <code>msg.schemaUrl</code></li>
+		<li>The node will transform a given JSON payload received in <code>msg.payload</code> using some JSONata rules, which URL is given in <code>msg.schemaUrl</code>.<br />
+			Alternatively, a static default value for the schema URL can be set in the corresponding property.</li>
 		<li>If any transformation is actually performed, the URL of the corresponding JSONata file is returned in <code>msg.transformUrl</code>.</li>
 		<li>The transformed payload is returned in <code>msg.payload</code>. If no <code>msg.schemaUrl</code> is provided, no transformation is performed.</li>
 		<li>Errors are returned on <code>msg.error</code></li>

json-multi-schema-transformer.js

@@ -15,6 +15,7 @@ module.exports = RED => {
 	function JsonMultiSchemaTransformerNode(config) {
 		RED.nodes.createNode(this, config);
 		const node = this;
+		const defaultSchemaUrl = config.defaultSchemaUrl;
 
 		let lastStatusError = true;
 		node.status({ fill:'grey', shape:'ring', text:'Uninitialized', });
@@ -62,6 +63,9 @@ module.exports = RED => {
 
 		node.on('input', async msg => {
 			msg.error = msg.error ? msg.error + ' ; ' : '';
+			if (!msg.schemaUrl) {
+				msg.schemaUrl = defaultSchemaUrl;
+			}
 			if (msg.schemaUrl) {
 				msg.transformUrl = msg.schemaUrl;
 				try {

package-lock.json

@@ -1,6 +1,6 @@
 {
 	"name": "node-red-contrib-json-multi-schema",
-	"version": "1.0.6",
+	"version": "1.1.0",
 	"description": "Generic JSON data pipeline tools, with dynamic transformation (using JSONata rules), resolving JSON Schema (using JSONata rules), and then validation (using JSON Schema). For Node-RED and for command-line.",
 	"main": "index.js",
 	"readmeFilename": "readme.md",
@@ -31,13 +31,13 @@
 		"url": "https://github.com/alexandrainst/node-red-contrib-json-multi-schema.git"
 	},
 	"dependencies": {
-		"ajv": "^6.10.2",
+		"ajv": "^6.11.0",
 		"jsonata": "^1.7.0",
 		"node-fetch": "^2.6.0",
-		"node-red-contrib-mock-cli": "^1.0.6"
+		"node-red-contrib-mock-cli": "^1.0.7"
 	},
 	"devDependencies": {
-		"jshint": "^2.10.3"
+		"jshint": "^2.11.0"
 	},
 	"jshintConfig": {
 		"esversion": 8,