docs: transaction

docs/uniCloud/cf-database.md

@@ -1501,6 +1501,7 @@ exports.main = async (event) => {
       const bbbRes = await transaction.collection('account').doc('bbb').get()
 
       if (aaaRes.data && bbbRes.data) {
+        try {
           const updateAAARes = await transaction.collection('account').doc('aaa').update({
             data: {
               amount: _.inc(-10)
@@ -1519,6 +1520,10 @@ exports.main = async (event) => {
           return {
             aaaAccount: aaaRes.data.amount - 10,
           }
+        } catch(e) {
+          // 会作为 runTransaction reject 的结果出去
+          await transaction.rollback(-100)
+        }
       } else {
         // 会作为 runTransaction reject 的结果出去
         await transaction.rollback(-100)
@@ -1568,8 +1573,8 @@ const db = uniCloud.database()
 const _ = db.command
 
 exports.main = async (event) => {
-  try {
   const transaction = await db.startTransaction()
+  try {
 
     const aaaRes = await transaction.collection('account').doc('aaa').get()
     const bbbRes = await transaction.collection('account').doc('bbb').get()
@@ -1596,7 +1601,6 @@ exports.main = async (event) => {
         aaaAccount: aaaRes.data.amount - 10,
       }
     } else {
-      await transaction.rollback()
 
       return {
         success: false,
@@ -1605,6 +1609,7 @@ exports.main = async (event) => {
       }
     }
   } catch (e) {
+    await transaction.rollback()
     console.error(`transaction error`, e)
 
     return {