javascript - Resolving or Rejecting a Promise while iterating through object properties -


this question has answer here:

i tried reject promise while iterating through object properties, execution continues after reject method called ("passed here!!!" logged in console, after rejection).

function updatedocumentwithnewdata(document, newdata) {   return new promise(function(resolve, reject) {      //some code...      (let key in newdata) {        if (newdata.hasownproperty(key)) {          //verifying if document has property          if (document.hasownproperty(key)) {            reject({'message' : 'a property exists...'});          }          //some code...        }      }                //some more code...      console.log("passed here!!!");      resolve(document);    });   }

i'm calling method returns promise this:

updatedocumentwithnewdata(doc, data).then(function(result) {    //some code    }).catch(function(err) {    //some code  });

the solution use boolean variable, , call "reject" method after loop finishes:

function updatedocumentwithnewdata(document, newdata) {    return new promise(function(resolve, reject) {      //some code...      let invalidupdate = false;      (let key in newdata) {        if (newdata.hasownproperty(key)) {          //verifying if document has property          if (document.hasownproperty(key)) {            invalidupdate = true;            break;          }          //some code...        }      }      if (invalidupdate) {        reject({'message' : 'a property exists...'});      }            //some more code...      console.log("passed here!!!");      resolve(document);    });   }

i don't know if i'm missing stupid, think rejection of promise should return imediatelly when "reject" called , break remaining code execution, first code should work. there i'm missing?

calling reject won't stop promise executing, it'll set promise's state rejected. doesn't make promise break code execution. (however, won't have problems calling resolve later, promise's state can changed pending rejected or fulfilled once)

if want break code execution, need use return reject(reason) (or return resolve(value)). otherwise, promise run until end of code, , then .then callbacks associated promise called. intended behavior. way stop promise execution throw error, cause promise reject error.

so way make original code work is:

function updatedocumentwithnewdata(document, newdata) {  return new promise(function(resolve, reject) {     //some code...     (let key in newdata) {       if (newdata.hasownproperty(key)) {         //verifying if document has property         if (document.hasownproperty(key)) {           return reject({'message' : 'a property exists...'});         }         //some code...       }     }      //some more code...     console.log("passed here!!!");     resolve(document);   });  }

Comments

Post a Comment

Popular posts from this blog

c# - Update a combobox from a presenter (MVP) -

i using mvp in project, new in mvp. have 2 comboboxes. when select option in combobox, combobox should filled new data. this action in presenter. view 'view1' in presenter, , introduced combobox1 , combobox2 properties in 'view1', because need 'datasource', 'displaymember', 'valuemember' , 'refresh()' in method below. but, when using pattern, enough send property like public string combobox2 { { return combobox1.selectedvalue.tosstring(); } } into presenter not whole combobox. how can solve problem? public void onselectedindexchangedcombobox1() { if (view1.combobox1.selectedindex == -1) { return; } datatable dt = tools.getdatatable("a path"); var query = (from o in dt.asenumerable() o.field<string>("afield") == farmerview.combobox1.selectedvalue.tostring() orderby o.field<string>("anotherfield") select...
Read more

How to understand 2 main() functions after using uftrace to profile the C++ program? -

i trying uftrace profile following simple c++ program: #include <iostream> class { public: a() {std::cout << "a created" << std::endl;} ~a() {std::cout << "a destroyed" << std::endl;} }; int main() { a; return 0; } the profile result this: # uftrace a.out created destroyed # duration tid function 2.026 [ 4828] | __cxa_atexit(); [ 4828] | main() { [ 4828] | __static_initialization_and_destruction_0() { 89.397 [ 4828] | std::ios_base::init::init(); 0.768 [ 4828] | __cxa_atexit(); 93.029 [ 4828] | } /* __static_initialization_and_destruction_0 */ 94.425 [ 4828] | } /* main */ [ 4828] | main() { [ 4828] | a::a() { 11.104 [ 4828] | std::operator <<(); 10.825 [ 4828] | std::basic_ostream::operator <<(); 24.514 [ 4828] | } /* a::a */ [ 4828] | a::~a() { 0.978 [ 4828] | ...
Read more

How to put a lock and transaction on table using spring 4 or above using jdbcTemplate and annotations like @Transactional? -

i trying put lock on table while writing on table , if happened in between roll-back . trying convert below code lock table test_g1 read; lock table test_g write; -- begin; start transaction; insert test_g1 values(143); insert test_g values(145); select * test_g1; select * test_g; rollback; select * test_g; unlock tables; how convert above code @transactional spring jdbctemplate code? @transactional(rollbackfor={dataaccessexception.class}) public void test(){ jdbctemplate.execute("insert test1 (id, nam) values (4, 'a')"); throw new dataaccessexception("error") { }; } here trying throw error, insert statement should rollback it's not happening . thanks edit-1 attaching code , doing in jdbcdaoimpl.java , mentioned problem comment above test() . app.java package com.cgiri.javabrains.spring4; import org.springframework.beans.factory.annotation.autowired; import org.springframework.context.applic...
Read more