11/* jshint esversion:8, node:true, strict:true */
22/**
33 * Node-RED node transforming a JSON observation from whichever format to another format using a specified JSONata URL.
4- * Schemas are automatically downloaded and cached the first time they are needed.
4+ * Schemas are automatically downloaded and cached on disk the first time they are needed.
55 * JSONata expressions are cached in memory.
66 */
77
8+ //JSONata: A declarative open-source query and transformation language for JSON data.
89const jsonata = require ( 'jsonata' ) ;
910const util = require ( 'util' ) ;
1011
@@ -14,105 +15,80 @@ module.exports = RED => {
1415 function JsonMultiSchemaTransformerNode ( config ) {
1516 RED . nodes . createNode ( this , config ) ;
1617 const node = this ;
17- const transformsUrl = config . transformsUrl ;
1818
1919 let lastStatusError = true ;
2020 node . status ( { fill :'grey' , shape :'ring' , text :'Uninitialized' , } ) ;
2121
2222 const jsonCache = require ( './json-cache.js' ) ( node ) ;
2323
24- /**
25- * Find the URL to the JSONata expression to use for the given payload.
26- */
27- async function resolveAsync ( payload ) {
28- const transforms = await jsonCache . loadAsync ( transformsUrl ) ;
29- let transformUrl = '' ;
30- for ( const mapping of transforms ) {
31- if ( mapping . query && mapping . cases ) {
32- const expression = jsonata ( mapping . query ) ;
33- let match = expression . evaluate ( payload ) ;
34- if ( match ) {
35- if ( match === true ) {
36- //Special case for boolean
37- match = "true" ;
38- }
39- const result = mapping . cases [ match ] ;
40- if ( result ) {
41- transformUrl = result ;
42- break ;
43- }
44- }
45- }
46- }
47- return transformUrl ;
48- }
49-
5024 //Cache of JSONata expressions
5125 const jsonatas = { } ;
5226
5327 /**
5428 * Transform the given payload with the JSONata expression given in URL.
5529 */
5630 async function transformAsync ( payload , transformUrl ) {
57- if ( transformUrl ) {
58- let jsonataExpression ;
59- let jsonataCache = jsonatas [ transformUrl ] ;
60- if ( jsonataCache ) {
61- if ( jsonataCache . expression === null ) {
62- //Wait for another task to be done building the same JSONata, so that we can use its cache
63- await new Promise ( ( resolve , reject ) => jsonataCache . mutexQueue . push ( resolve ) ) ;
64- }
65- jsonataExpression = jsonataCache . expression ;
66- } else {
67- //Build JSONata expression for the given transformation URL
68- jsonataCache = { expression : null , mutexQueue : [ ] } ;
69- jsonatas [ transformUrl ] = jsonataCache ;
70- const transform = await jsonCache . loadAsync ( transformUrl , false ) ;
71- node . debug ( 'Build JSONata expression for: ' + transformUrl ) ;
72- jsonataExpression = jsonata ( transform ) ;
73- jsonataCache . expression = jsonataExpression ;
31+ if ( ! transformUrl ) {
32+ return 'Error: Invalid JSONata URL' ;
33+ }
7434
75- //Resume tasks waiting for the same JSONata expression
76- let next ;
77- while ( ( next = jsonataCache . mutexQueue . shift ( ) ) != undefined ) {
78- next ( ) ; //Resolve promise
79- }
35+ let jsonataExpression ;
36+ let jsonataCache = jsonatas [ transformUrl ] ;
37+ if ( jsonataCache ) {
38+ if ( jsonataCache . expression === null ) {
39+ //Wait for another task to be done building the same JSONata, so that we can use its cache
40+ await new Promise ( ( resolve , reject ) => jsonataCache . mutexQueue . push ( resolve ) ) ;
8041 }
42+ jsonataExpression = jsonataCache . expression ;
43+ } else {
44+ //Build JSONata expression for the given transformation URL
45+ jsonataCache = { expression : null , mutexQueue : [ ] } ;
46+ jsonatas [ transformUrl ] = jsonataCache ;
47+ const transform = await jsonCache . loadAsync ( transformUrl , false ) ;
48+ node . debug ( 'Build JSONata expression for: ' + transformUrl ) ;
49+ jsonataExpression = jsonata ( transform ) ;
50+ jsonataCache . expression = jsonataExpression ;
8151
82- if ( jsonataExpression ) {
83- //Perform transformation
84- return jsonataExpression . evaluate ( payload ) ;
52+ //Resume tasks waiting for the same JSONata expression
53+ let next ;
54+ while ( ( next = jsonataCache . mutexQueue . shift ( ) ) != undefined ) {
55+ next ( ) ; //Resolve promise
8556 }
8657 }
58+
59+ if ( jsonataExpression ) {
60+ //Perform transformation
61+ return jsonataExpression . evaluate ( payload ) ;
62+ }
63+
8764 return false ;
8865 }
8966
9067 node . on ( 'input' , async msg => {
91- delete msg . transformUrl ;
9268 msg . error = msg . error ? msg . error + ' ; ' : '' ;
93- try {
94- const transformUrl = await resolveAsync ( msg . payload ) ;
95- if ( transformUrl != '' ) {
96- msg . transformUrl = transformUrl ;
97- const result = await transformAsync ( msg . payload , msg . transformUrl ) ;
69+ if ( msg . schemaUrl == '' ) {
70+ msg . error += 'Unknown schema!' ;
71+ } else {
72+ msg . transformUrl = msg . schemaUrl ;
73+ try {
74+ const result = await transformAsync ( msg . payload , msg . schemaUrl ) ;
9875 if ( result ) {
9976 msg . payload = result ;
10077 msg . error = msg . error != '' ;
10178 } else {
102- lastStatusError = true ;
103- node . status ( { fill :'red' , shape :'ring' , text :'Error' , } ) ;
104- msg . error += util . format ( 'Failed tranforming using "%s"' , transformsUrl ) ;
79+ msg . error += util . format ( 'Failed tranforming using "%s"' , msg . schemaUrl ) ;
10580 }
10681 if ( lastStatusError ) {
10782 node . status ( { fill :'green' , shape :'dot' , text :'OK' , } ) ;
10883 lastStatusError = false ;
10984 }
85+ } catch ( ex ) {
86+ lastStatusError = true ;
87+ node . status ( { fill :'red' , shape :'ring' , text :'Error' , } ) ;
88+ msg . error += util . format ( 'Error tranforming using "%s": %s' , msg . schemaUrl , ex ) ;
11089 }
111- } catch ( ex ) {
112- lastStatusError = true ;
113- node . status ( { fill :'red' , shape :'ring' , text :'Error' , } ) ;
114- msg . error += util . format ( 'Error tranforming using "%s": %s : %s' , transformsUrl , ex , JSON . stringify ( msg . payload ) ) ;
11590 }
91+ delete msg . schemaUrl ;
11692 node . send ( msg ) ;
11793 } ) ;
11894 }
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