From da065985032a7e02cd07a843e0703a1446505b03 Mon Sep 17 00:00:00 2001
From: Akhil Reddy <akhil.reddy@qualyval.com>
Date: Fri, 31 Jan 2025 11:12:51 +0530
Subject: [PATCH] updated filter parser

---
 src/pagination.ts        |  12 +----
 src/utils/queryParser.ts | 106 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 108 insertions(+), 10 deletions(-)
 create mode 100644 src/utils/queryParser.ts

diff --git a/src/pagination.ts b/src/pagination.ts
index 1ff21d1..bb9165c 100644
--- a/src/pagination.ts
+++ b/src/pagination.ts
@@ -1,4 +1,5 @@
 import { z } from "zod";
+import { parse } from "./utils/queryParser";
 
 export const pageMetadata = z.object({
   count: z.number(),
@@ -43,16 +44,7 @@ export function getFilterObject(
   const filterObj: Array<{}> = [];
 
   if (params.filter && params.filter != "") {
-    const filterOptions = params.filter.split(",");
-    filterOptions.forEach((item) => {
-      if (item.includes("!=")) {
-        const [key, val] = item.split("!=").map((token) => token.trim());
-        if (validFields.includes(key)) filterObj.push({ [key]: { $ne: val } });
-      } else if (item.includes("=")) {
-        const [key, val] = item.split("=").map((token) => token.trim());
-        if (validFields.includes(key)) filterObj.push({ [key]: { $eq: val } });
-      }
-    });
+    filterObj.push(...parse(params.filter, validFields));
   }
 
   return filterObj;
diff --git a/src/utils/queryParser.ts b/src/utils/queryParser.ts
new file mode 100644
index 0000000..76549d5
--- /dev/null
+++ b/src/utils/queryParser.ts
@@ -0,0 +1,106 @@
+import mongoose from "mongoose";
+
+type ParsedQuery = Array<
+  Record<
+    string,
+    Record<"$eq" | "$neq" | "$in" | "$nin", string | Date | Object>
+  >
+>;
+
+function convertValue(value: any) {
+  if (mongoose.Types.ObjectId.isValid(value)) {
+    return mongoose.Types.ObjectId.createFromHexString(value);
+  } else if (!isNaN(Date.parse(value))) {
+    return new Date(value);
+  } else {
+    return value;
+  }
+}
+
+export function parse(query: string, validFields: Array<string>): ParsedQuery {
+  const result = [];
+
+  let currentStage = "field";
+  let token = "";
+  let field = "";
+  let op = "";
+  let value = "";
+  let valueArr = [];
+  for (let i = 0; i < query.length; i++) {
+    let char = query[i];
+
+    if (currentStage === "field") {
+      if (char === "=" || char === "!") {
+        field = token;
+        token = "";
+        currentStage = "value";
+
+        if (char === "=") {
+          op = "$eq";
+        } else {
+          op = "$neq";
+          i++;
+        }
+
+        continue;
+      }
+
+      token += char;
+    }
+
+    if (currentStage === "value") {
+      if (char === "[") {
+        currentStage = "valueArr";
+        continue;
+      }
+
+      if (char === "," || i == query.length - 1) {
+        if (i == query.length - 1) token += char;
+
+        value = token;
+        if (validFields.includes(field))
+          result.push({ [field]: { [op]: convertValue(value) } });
+
+        token = "";
+        field = "";
+        op = "";
+
+        currentStage = "field";
+
+        continue;
+      }
+
+      token += char;
+    }
+
+    if (currentStage === "valueArr") {
+      if (char === ",") {
+        valueArr.push(convertValue(token));
+        token = "";
+        continue;
+      }
+
+      if (char === "]") {
+        valueArr.push(token);
+        if (validFields.includes(field))
+          result.push({
+            [field]: { [op === "$eq" ? "$in" : "$nin"]: valueArr },
+          });
+
+        token = "";
+        field = "";
+        op = "";
+        valueArr = [];
+
+        currentStage = "field";
+        i++;
+
+        continue;
+      }
+
+      token += char;
+    }
+  }
+
+  return result;
+}