Use base58 to encode json (#33)

* use base58 to encode json

* fix base58 term to base64

* allow null json field

base64.js

@@ -0,0 +1,21 @@
+// SNS -> SQS subscription could not filter message
+// if the message contains a stringified JSON
+// use base64 to encode str instead
+// https://stackoverflow.com/questions/59853890/sns-subscription-filter-policies-do-not-seem-to-work-when-a-binary-message-attri
+
+function encodeJson(json) {
+  const jsonStr = JSON.stringify(json);
+  const buff = Buffer.from(jsonStr);
+  return buff.toString("base64");
+}
+
+function decodeJson(base64) {
+  const buff = Buffer.from(base64, "base64");
+  const jsonStr = buff.toString("utf-8");
+  return JSON.parse(jsonStr);
+}
+
+module.exports = {
+  encodeJson,
+  decodeJson
+};

index.js

@@ -1,4 +1,5 @@
 const AWS = require("aws-sdk");
+const { encodeJson, decodeJson } = require("./base64");
 
 const sns = new AWS.SNS({
   apiVersion: "2010-03-31",
@@ -134,13 +135,6 @@ function dispatch({ type, uri, id, checksum, source, message, json }) {
     throw new InvalidEventMessageError("event message is required");
   }
 
-  let jsonStr;
-  try {
-    jsonStr = JSON.stringify(Object.assign({ type, id }, json));
-  } catch (e) {
-    throw new InvalidEventJsonError("event json is invalid");
-  }
-
   const messageAttributes = {
     type: {
       DataType: "String",
@@ -153,10 +147,6 @@ function dispatch({ type, uri, id, checksum, source, message, json }) {
     source: {
       DataType: "String",
       StringValue: source
-    },
-    json: {
-      DataType: "String",
-      StringValue: jsonStr
     }
   };
 
@@ -174,6 +164,17 @@ function dispatch({ type, uri, id, checksum, source, message, json }) {
     };
   }
 
+  if (json) {
+    try {
+      messageAttributes.json = {
+        DataType: "String",
+        StringValue: encodeJson(json)
+      };
+    } catch (e) {
+      throw new InvalidEventJsonError("event json is invalid");
+    }
+  }
+
   const eventParams = {
     MessageAttributes: messageAttributes,
     TopicArn: process.env.AWS_SNS_TOPIC_ARN,
@@ -245,11 +246,11 @@ function mapAttributes(data) {
     if (data.MessageAttributes[currentValue]) {
       if (currentValue === "json") {
         try {
-          accumulator[currentValue] = JSON.parse(
+          accumulator[currentValue] = decodeJson(
             data.MessageAttributes[currentValue].Value
           );
         } catch (e) {
-          throw new InvalidEventJsonError(`unable to parse json`);
+          console.log(e);
         }
       } else {
         accumulator[currentValue] = data.MessageAttributes[currentValue].Value;

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@luxuryescapes/lib-events",
-  "version": "1.0.32",
+  "version": "1.0.33",
   "main": "index.js",
   "scripts": {
     "test": "./node_modules/.bin/jest && yarn run lint",