feat(exclude-properties): support excluding properties from the response

Author: OliverDudgeon

pnpm-lock.yaml

@@ -1,25 +1,44 @@
 import type { SDFRecord } from "./parser";
 
+export const filterExcludedProperties = (
+  record: SDFRecord,
+  excludedProperties: string[],
+): SDFRecord => {
+  const filteredProperties = Object.keys(record.properties)
+    .filter((key) => !excludedProperties.includes(key))
+    .reduce<SDFRecord["properties"]>((obj, key) => {
+      const val = record.properties[key];
+      val !== undefined && (obj[key] = val);
+      return obj;
+    }, {});
+
+  return {
+    ...record,
+    properties: filteredProperties,
+  };
+};
+
 export type FilterFn = (record: SDFRecord) => boolean;
 
 export type FilterRule = {
   property: string;
   min: number;
   max: number;
-  treatAs: "number" | "string" | "date";
+  treatAs: "string" | "number" | "integer" | "object" | "array" | "boolean" | "null";
 };
 
 export const filterRecord = (record: SDFRecord, rules: FilterRule[]): boolean => {
   for (const rule of rules) {
     const value = record.properties[rule.property];
-    // skip a record that is missing a property to which we apply a filter
+    // skip the filter check if the property is missing from the record
     if (value === undefined) continue;
 
     // handle each type of filter
     switch (rule.treatAs) {
-      case "number": {
+      case "number":
+      case "integer": {
         if (value === "") return false;
-        // parseFloat has issues so should probably use a different library
+        // parseFloat has issues so should probably use a library
         const numberValue = Number.parseFloat(value);
         // if the value is not parsable to a number, drop the record
         if (Number.isNaN(numberValue)) return false;
@@ -29,7 +48,10 @@ export const filterRecord = (record: SDFRecord, rules: FilterRule[]): boolean =>
       }
       // TODO: To implement
       case "string":
-      case "date":
+      case "object":
+      case "array":
+      case "boolean":
+      case "null":
         continue;
     }
   }

src/filter.ts

@@ -1,6 +1,6 @@
 import { Transform, type TransformCallback, type TransformOptions } from "node:stream";
 
-import type { FilterFn } from "./filter";
+import { filterExcludedProperties, type FilterFn } from "./filter";
 import type { SDFRecord } from "./parser";
 import { parseSdPart } from "./parser";
 import { splitLines } from "./utils";
@@ -44,6 +44,7 @@ const countRecords = (buffer: string) => buffer.match(/\${4}.*/g)?.length ?? 0;
 export class NodeSDFTransformer extends Transform {
   constructor(
     private filter: FilterFn = () => true,
+    private excludedProperties: string[] = [],
     options?: TransformOptions,
     // these shouldn't be in the constructor definition but how set these to this without ts complaining?
     private buffer = "",
@@ -74,7 +75,10 @@ export class NodeSDFTransformer extends Transform {
       const record = this.parse();
       if (this.filter(record)) {
         if (this.record) {
-          const json = JSON.stringify(this.record);
+          const json = JSON.stringify(
+            filterExcludedProperties(this.record, this.excludedProperties),
+          );
+
           this.push(json + ",");
           this.record = record;
         } else {
@@ -90,7 +94,7 @@ export class NodeSDFTransformer extends Transform {
     const record = this.record;
 
     if (record) {
-      const json = JSON.stringify(record);
+      const json = JSON.stringify(filterExcludedProperties(record, this.excludedProperties));
       this.push(json);
     }
 

src/node-stream.ts

@@ -1,4 +1,4 @@
-import type { FilterFn } from "./filter";
+import { filterExcludedProperties, type FilterFn } from "./filter";
 import { parseSdPart, type SDFRecord } from "./parser";
 import { splitLines } from "./utils";
 
@@ -20,7 +20,10 @@ const RECORD_SEPARATOR = "$$$$";
   ```
  * @returns instance of `TransformStream`
  */
-export const createSDFTransformer = (filter: FilterFn = () => true) => {
+export const createSDFTransformer = (
+  filter: FilterFn = () => true,
+  excludedProperties: string[] = [],
+) => {
   let content = ""; // accumulator for the content of the current record
 
   // TransformStream to be used with stream.pipeThrough()
@@ -37,7 +40,7 @@ export const createSDFTransformer = (filter: FilterFn = () => true) => {
         content = content.slice(recordEndIndex + RECORD_SEPARATOR.length + 1);
 
         if (filter(record)) {
-          controller.enqueue(record);
+          controller.enqueue(filterExcludedProperties(record, excludedProperties));
         }
       }
     },