From 2781640a2aac17d5cc8cdb7b2d85175c767e8be5 Mon Sep 17 00:00:00 2001
From: n1073645 <n1073645@gmail.com>
Date: Wed, 29 Jul 2020 15:27:55 +0100
Subject: [PATCH] JSON to CSV improvements

---
 src/core/operations/JSONToCSV.mjs    | 79 +++++++++++++++++-----------
 tests/operations/tests/JSONtoCSV.mjs | 66 +++++++++++++++++++++++
 2 files changed, 115 insertions(+), 30 deletions(-)

diff --git a/src/core/operations/JSONToCSV.mjs b/src/core/operations/JSONToCSV.mjs
index e846f164..c363acbe 100644
--- a/src/core/operations/JSONToCSV.mjs
+++ b/src/core/operations/JSONToCSV.mjs
@@ -6,6 +6,8 @@
 
 import Operation from "../Operation.mjs";
 import OperationError from "../errors/OperationError.mjs";
+import * as flat from "flat";
+const flatten = flat.default ? flat.default.flatten : flat.flatten;
 
 /**
  * JSON to CSV operation
@@ -38,6 +40,40 @@ class JSONToCSV extends Operation {
         ];
     }
 
+    /**
+     * Converts a JSON to csv equivalent.
+     *
+     * @returns {string}
+     */
+    toCsv() {
+        const self = this;
+        // If the JSON is an array of arrays, this is easy
+        if (this.flattened[0] instanceof Array) {
+            return this.flattened
+                .map(row => row
+                    .map(self.escapeCellContents.bind(self))
+                    .join(this.cellDelim)
+                )
+                .join(this.rowDelim) +
+                this.rowDelim;
+        }
+
+        // If it's an array of dictionaries...
+        const header = Object.keys(this.flattened[0]);
+        return header
+            .map(self.escapeCellContents.bind(self))
+            .join(this.cellDelim) +
+            this.rowDelim +
+            this.flattened
+                .map(row => header
+                    .map(h => row[h])
+                    .map(self.escapeCellContents.bind(self))
+                    .join(this.cellDelim)
+                )
+                .join(this.rowDelim) +
+                this.rowDelim;
+    }
+
     /**
      * @param {JSON} input
      * @param {Object[]} args
@@ -49,40 +85,23 @@ class JSONToCSV extends Operation {
         // Record values so they don't have to be passed to other functions explicitly
         this.cellDelim = cellDelim;
         this.rowDelim = rowDelim;
-        const self = this;
-
-        if (!(input instanceof Array)) {
-            input = [input];
+        this.flattened = input;
+        if (!(this.flattened instanceof Array)) {
+            this.flattened = [input];
         }
 
         try {
-            // If the JSON is an array of arrays, this is easy
-            if (input[0] instanceof Array) {
-                return input
-                    .map(row => row
-                        .map(self.escapeCellContents.bind(self))
-                        .join(cellDelim)
-                    )
-                    .join(rowDelim) +
-                    rowDelim;
-            }
-
-            // If it's an array of dictionaries...
-            const header = Object.keys(input[0]);
-            return header
-                .map(self.escapeCellContents.bind(self))
-                .join(cellDelim) +
-                rowDelim +
-                input
-                    .map(row => header
-                        .map(h => row[h])
-                        .map(self.escapeCellContents.bind(self))
-                        .join(cellDelim)
-                    )
-                    .join(rowDelim) +
-                rowDelim;
+            return this.toCsv();
         } catch (err) {
-            throw new OperationError("Unable to parse JSON to CSV: " + err.toString());
+            try {
+                this.flattened = flatten(input);
+                if (!(this.flattened instanceof Array)) {
+                    this.flattened = [this.flattened];
+                }
+                return this.toCsv();
+            } catch (err) {
+                throw new OperationError("Unable to parse JSON to CSV: " + err.toString());
+            }
         }
     }
 
diff --git a/tests/operations/tests/JSONtoCSV.mjs b/tests/operations/tests/JSONtoCSV.mjs
index 195bce3d..a9a0867e 100644
--- a/tests/operations/tests/JSONtoCSV.mjs
+++ b/tests/operations/tests/JSONtoCSV.mjs
@@ -89,5 +89,71 @@ TestRegister.addTests([
                 args: [",", "\\r\\n"]
             },
         ],
+    },
+    {
+        name: "JSON to CSV: nested JSON",
+        input: JSON.stringify({a: 1, b: {c: 2, d: 3}}),
+        expectedOutput: "a,b.c,b.d\r\n1,2,3\r\n",
+        recipeConfig: [
+            {
+                op: "JSON to CSV",
+                args: [",", "\\r\\n"]
+            },
+        ],
+    },
+    {
+        name: "JSON to CSV: nested array",
+        input: JSON.stringify({a: 1, b: [2, 3]}),
+        expectedOutput: "a,b.0,b.1\r\n1,2,3\r\n",
+        recipeConfig: [
+            {
+                op: "JSON to CSV",
+                args: [",", "\\r\\n"]
+            },
+        ],
+    },
+    {
+        name: "JSON to CSV: nested JSON, nested array",
+        input: JSON.stringify({a: 1, b: {c: [2, 3], d: 4}}),
+        expectedOutput: "a,b.c.0,b.c.1,b.d\r\n1,2,3,4\r\n",
+        recipeConfig: [
+            {
+                op: "JSON to CSV",
+                args: [",", "\\r\\n"]
+            },
+        ],
+    },
+    {
+        name: "JSON to CSV: nested array, nested JSON",
+        input: JSON.stringify({a: 1, b: [{c: 3, d: 4}]}),
+        expectedOutput: "a,b.0.c,b.0.d\r\n1,3,4\r\n",
+        recipeConfig: [
+            {
+                op: "JSON to CSV",
+                args: [",", "\\r\\n"]
+            },
+        ],
+    },
+    {
+        name: "JSON to CSV: nested array, nested array",
+        input: JSON.stringify({a: 1, b: [[2, 3]]}),
+        expectedOutput: "a,b.0.0,b.0.1\r\n1,2,3\r\n",
+        recipeConfig: [
+            {
+                op: "JSON to CSV",
+                args: [",", "\\r\\n"]
+            },
+        ],
+    },
+    {
+        name: "JSON to CSV: nested JSON, nested JSON",
+        input: JSON.stringify({a: 1, b: { c: { d: 2, e: 3}}}),
+        expectedOutput: "a,b.c.d,b.c.e\r\n1,2,3\r\n",
+        recipeConfig: [
+            {
+                op: "JSON to CSV",
+                args: [",", "\\r\\n"]
+            },
+        ],
     }
 ]);