JSONPath: Add ability to select root node for appending/modifying

gorhill · gorhill · commit faff03520343 · 2025-08-09T13:56:02.000-04:00
As discussed with filter list maintainers.

Examples of usage:

  $ =&gt; result is `null`
  $+={"modifyOrCreate": "..."}

These expressions were not working with previous version.
diff --git a/src/js/jsonpath.js b/src/js/jsonpath.js
@@ -124,12 +124,12 @@ export class JSONPath {
         return paths;
     }
     apply(root) {
-        if ( this.valid === false ) { return 0; }
+        if ( this.valid === false ) { return; }
         const { rval } = this.#compiled;
-        this.#root = root;
+        this.#root = { '$': root };
         const paths = this.#evaluate(this.#compiled.steps, []);
-        const n = paths.length;
-        let i = n;
+        let i = paths.length
+        if ( i === 0 ) { this.#root = null; return; }
         while ( i-- ) {
             const { obj, key } = this.#resolvePath(paths[i]);
             if ( rval !== undefined ) {
@@ -140,8 +140,9 @@ export class JSONPath {
                 delete obj[key];
             }
         }
+        const result = this.#root['$'] ?? null;
         this.#root = null;
-        return n;
+        return result;
     }
     dump() {
         return JSON.stringify(this.#compiled);
@@ -166,8 +167,15 @@ export class JSONPath {
         if ( query.length === 0 ) { return; }
         const steps = [];
         let c = query.charCodeAt(i);
-        steps.push({ mv: c === 0x24 /* $ */ ? this.#ROOT : this.#CURRENT });
-        if ( c === 0x24 /* $ */ || c === 0x40 /* @ */ ) { i += 1; }
+        if ( c === 0x24 /* $ */ ) {
+            steps.push({ mv: this.#ROOT });
+            i += 1;
+        } else if ( c === 0x40 /* @ */ ) {
+            steps.push({ mv: this.#CURRENT });
+            i += 1;
+        } else {
+            steps.push({ mv: i === 0 ? this.#ROOT : this.#CURRENT });
+        }
         let mv = this.#UNDEFINED;
         for (;;) {
             if ( i === query.length ) { break; }
@@ -229,7 +237,8 @@ export class JSONPath {
             i = r.i + 1;
             mv = this.#UNDEFINED;
         }
-        if ( steps.length <= 1 ) { return; }
+        if ( steps.length === 0 ) { return; }
+        if ( mv !== this.#UNDEFINED ) { return; }
         return { steps, i };
     }
     #evaluate(steps, pathin) {
@@ -238,7 +247,7 @@ export class JSONPath {
         for ( const step of steps ) {
             switch ( step.mv ) {
             case this.#ROOT:
-                resultset = [ [] ];
+                resultset = [ [ '$' ] ];
                 break;
             case this.#CURRENT:
                 resultset = [ pathin ];
diff --git a/src/js/resources/json-edit.js b/src/js/resources/json-edit.js
@@ -51,12 +51,13 @@ function editOutboundObjectFn(
     }
     proxyApplyFn(propChain, function(context) {
         const obj = context.reflect();
-        if ( jsonp.apply(obj) === 0 ) { return obj; }
+        const objAfter = jsonp.apply(obj);
+        if ( objAfter === undefined ) { return obj; }
         safe.uboLog(logPrefix, 'Edited');
         if ( safe.logLevel > 1 ) {
-            safe.uboLog(logPrefix, `After edit:\n${safe.JSON_stringify(obj, null, 2)}`);
+            safe.uboLog(logPrefix, `After edit:\n${safe.JSON_stringify(objAfter, null, 2)}`);
         }
-        return obj;
+        return objAfter;
     });
 }
 registerScriptlet(editOutboundObjectFn, {
@@ -206,12 +207,13 @@ function editInboundObjectFn(
         } catch {
         }
         if ( typeof clone !== 'object' || clone === null ) { return; }
-        if ( jsonp.apply(clone) === 0 ) { return; }
+        const objAfter = jsonp.apply(clone);
+        if ( objAfter === undefined ) { return; }
         safe.uboLog(logPrefix, 'Edited');
         if ( safe.logLevel > 1 ) {
-            safe.uboLog(logPrefix, `After edit:\n${safe.JSON_stringify(clone, null, 2)}`);
+            safe.uboLog(logPrefix, `After edit:\n${safe.JSON_stringify(objAfter, null, 2)}`);
         }
-        return clone;
+        return objAfter;
     };
     proxyApplyFn(propChain, function(context) {
         const i = getArgPos(context.args);
@@ -343,13 +345,17 @@ function jsonEditXhrResponseFn(trusted, jsonq = '') {
             } else if ( typeof innerResponse === 'string' ) {
                 try { obj = safe.JSON_parse(innerResponse); } catch { }
             }
-            if ( typeof obj !== 'object' || obj === null || jsonp.apply(obj) === 0 ) {
+            if ( typeof obj !== 'object' || obj === null ) {
+                return (xhrDetails.response = innerResponse);
+            }
+            const objAfter = jsonp.apply(obj);
+            if ( objAfter === undefined ) {
                 return (xhrDetails.response = innerResponse);
             }
             safe.uboLog(logPrefix, 'Edited');
             const outerResponse = typeof innerResponse === 'string'
-                ? JSONPath.toJSON(obj, safe.JSON_stringify)
-                : obj;
+                ? JSONPath.toJSON(objAfter, safe.JSON_stringify)
+                : objAfter;
             return (xhrDetails.response = outerResponse);
         }
         get responseText() {
@@ -467,9 +473,9 @@ function jsonEditXhrRequestFn(trusted, jsonq = '') {
             try { data = safe.JSON_parse(body); }
             catch { }
             if ( data instanceof Object === false ) { return; }
-            const n = jsonp.apply(data);
-            if ( n === 0 ) { return; }
-            body = safe.JSON_stringify(data);
+            const objAfter = jsonp.apply(data);
+            if ( objAfter === undefined ) { return; }
+            body = safe.JSON_stringify(objAfter);
             safe.uboLog(logPrefix, 'Edited');
             if ( safe.logLevel > 1 ) {
                 safe.uboLog(logPrefix, `After edit:\n${body}`);
@@ -583,9 +589,10 @@ function jsonEditFetchResponseFn(trusted, jsonq = '') {
             const response = responseBefore.clone();
             return response.json().then(obj => {
                 if ( typeof obj !== 'object' ) { return responseBefore; }
-                if ( jsonp.apply(obj) === 0 ) { return responseBefore; }
+                const objAfter = jsonp.apply(obj);
+                if ( objAfter === undefined ) { return responseBefore; }
                 safe.uboLog(logPrefix, 'Edited');
-                const responseAfter = Response.json(obj, {
+                const responseAfter = Response.json(objAfter, {
                     status: responseBefore.status,
                     statusText: responseBefore.statusText,
                     headers: responseBefore.headers,
@@ -694,9 +701,9 @@ function jsonEditFetchRequestFn(trusted, jsonq = '') {
         try { data = safe.JSON_parse(body); }
         catch { }
         if ( data instanceof Object === false ) { return; }
-        const n = jsonp.apply(data);
-        if ( n === 0 ) { return; }
-        return safe.JSON_stringify(data);
+        const objAfter = jsonp.apply(data);
+        if ( objAfter === undefined ) { return; }
+        return safe.JSON_stringify(objAfter);
     }
     const proxyHandler = context => {
         const args = context.callArgs;
@@ -813,11 +820,12 @@ function jsonlEditFn(jsonp, text = '') {
             linesAfter.push(lineBefore);
             continue;
         }
-        if ( jsonp.apply(obj) === 0 ) {
+        const objAfter = jsonp.apply(obj);
+        if ( objAfter === undefined ) {
             linesAfter.push(lineBefore);
             continue;
         }
-        const lineAfter = safe.JSON_stringify(obj);
+        const lineAfter = safe.JSON_stringify(objAfter);
         linesAfter.push(lineAfter);
     }
     return linesAfter.join(lineSeparator);
diff --git a/src/js/traffic.js b/src/js/traffic.js
@@ -651,8 +651,9 @@ function textResponseFilterer(session, directives) {
             const json = session.getString();
             let obj;
             try { obj = JSON.parse(json); } catch { break; }
-            if ( cache.jsonp.apply(obj) === 0 ) { break; }
-            session.setString(cache.jsonp.toJSON(obj));
+            const objAfter = cache.jsonp.apply(obj);
+            if ( objAfter === undefined ) { break; }
+            session.setString(cache.jsonp.toJSON(objAfter));
             applied.push(directive);
             break;
         }
@@ -666,11 +667,12 @@ function textResponseFilterer(session, directives) {
                     linesAfter.push(lineBefore);
                     continue;
                 }
-                if ( cache.jsonp.apply(obj) === 0 ) {
+                const objAfter = cache.jsonp.apply(obj);
+                if ( objAfter === undefined ) {
                     linesAfter.push(lineBefore);
                     continue;
                 }
-                linesAfter.push(cache.jsonp.toJSON(obj));
+                linesAfter.push(cache.jsonp.toJSON(objAfter));
             }
             session.setString(linesAfter.join('\n'));
             break;
diff --git a/tools/jsonpath-tool.html b/tools/jsonpath-tool.html
@@ -150,12 +150,12 @@ <h2>uBO-flavored JSONPath tool</h2>
         const jsonpath = input.value;
         jsonp.compile(jsonpath);
         const jsonDataIn = readJSON();
-        const result = formatResult(jsonp.evaluate(jsonDataIn));
+        const left = formatResult(jsonp.evaluate(jsonDataIn));
         const pathsDiv = document.querySelector('#jsonpath-result');
-        pathsDiv.textContent = result;
+        pathsDiv.textContent = left;
         const jsonDataOut = readJSON();
-        jsonp.apply(jsonDataOut);
-        const bText = JSON.stringify(jsonDataOut, null, 2);
+        const objAfter = jsonp.apply(jsonDataOut);
+        const bText = JSON.stringify(objAfter !== undefined ? objAfter : jsonDataOut, null, 2);
         cmMergeView.b.dispatch({
             changes: {
                 from: 0, to: cmMergeView.b.state.doc.length,
