Added 'CSV to JSON' and 'JSON to CSV' operations. Closes #277

src/core/operations/JSONToCSV.mjs

@@ -0,0 +1,72 @@
+/**
+ * @author n1474335 [n1474335@gmail.com]
+ * @copyright Crown Copyright 2018
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation";
+import OperationError from "../errors/OperationError";
+
+/**
+ * JSON to CSV operation
+ */
+class JSONToCSV extends Operation {
+
+    /**
+     * JSONToCSV constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "JSON to CSV";
+        this.module = "Default";
+        this.description = "Converts JSON data to a CSV.";
+        this.infoURL = "https://wikipedia.org/wiki/Comma-separated_values";
+        this.inputType = "JSON";
+        this.outputType = "string";
+        this.args = [
+            {
+                name: "Cell delimiter",
+                type: "binaryShortString",
+                value: ","
+            },
+            {
+                name: "Row delimiter",
+                type: "binaryShortString",
+                value: "\\r\\n"
+            }
+        ];
+    }
+
+    /**
+     * @param {JSON} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+        const [cellDelim, rowDelim] = args;
+
+        try {
+            // If the JSON is an array of arrays, this is easy
+            if (input[0] instanceof Array) {
+                return input.map(row => row.join(cellDelim)).join(rowDelim) + rowDelim;
+            }
+
+            // If it's an array of dictionaries...
+            const header = Object.keys(input[0]);
+            return header.join(cellDelim) +
+                rowDelim +
+                input.map(
+                    row => header.map(
+                        h => row[h]
+                    ).join(cellDelim)
+                ).join(rowDelim) +
+                rowDelim;
+        } catch (err) {
+            throw new OperationError("Unable to parse JSON to CSV: " + err);
+        }
+    }
+
+}
+
+export default JSONToCSV;