Kotlin, Reactive programming : How to consume the value of one function output to another one

I am very new to Project reactor library and reactive programming with Kotlin, and trying to implement functions like flatmap, flatMapIterable, subscribe etc.
Now issue is I am trying to use the o/p of one function into another one using flatMapIterable, and after using I am trying to subscribe this, by passing the output of fist function and second one to another function of new class.
Now when I try to use the o/p of function 1, I am unable to see the value, I only see Mono<> or Flux<>.

Below is code snippet for more explanation

var result = employerService.getEmployee("Active") // return value is Mono<GetEmployeeStatusListResult>

result.flatMapIterable(GetEmployeeStatusListResult::emps)

      .flatMap {

          employerService.getUsersById(it.userId) // it is of type GetEmployeeStatusListResult.emps and  value returned from employerService.getUsersById(it.userId) is of type GetUserResult class created 

      }.subscribe {

          aService.createContact(result, it)    

      }

Now at line 4 I am getting expected userId out of it.userId, but when I inspect result at line 6, then I do not get the expected list of values, it just provides me MonomapFuesable, with mapper and source.

Can anyone please help me to understand what should I do, as my whole agenda is to pass the calculated value from line 1 and line 4 to line 6 function.
Please ask more question, if I haven't provided the required information, I am very new to this.
Thanks in advance !!

[UPDATE] : I have resolved the issue with the following way :
```

employerService.getEmployee("Active") // return value is Mono<GetEmployeeStatusListResult>

.flatMapIterable(GetEmployeeStatusListResult::emps)

          .flatMap {

              employerService.getUsersById(it.userId).map{x->Pair(it,x)} // it is of type GetEmployeeStatusListResult.emps and  value returned from employerService.getUsersById(it.userId) is of type GetUserResult class created 

          }.subscribe {

              aService.createContact(it.first, it.second)    

          }

```

edited Jan 3 at 10:05

asked Jan 2 at 7:07

user10374449

114

1

I think it will help if you list the types returned by each of the variables. At some point an observable is not being returned and that could be the problem.

– Mahesh
Jan 2 at 7:11

@Mahesh edited the code snippet with comment for each line return type, assuming you are asking for this only

– user10374449
Jan 2 at 7:20

This is Kotlin, right? RxJS, as its name indicates, is a JavaScript library. Not a Kotlin or Java library. What you're using (Mono, Flux, etc.) are types from the Reactor library. Not from RxJS. Edit your question, change its title and text and remove the RxJS tag: RxJS has nothing to do with your code.

– JB Nizet
Jan 2 at 7:59

Thanks @JBNizet for correcting me !! Do you have any suggestions/advice for the above questions, Please share your expertise!!

– user10374449
Jan 2 at 8:34

add a comment |

Below is code snippet for more explanation

var result = employerService.getEmployee("Active") // return value is Mono<GetEmployeeStatusListResult>

result.flatMapIterable(GetEmployeeStatusListResult::emps)

      .flatMap {

          employerService.getUsersById(it.userId) // it is of type GetEmployeeStatusListResult.emps and  value returned from employerService.getUsersById(it.userId) is of type GetUserResult class created 

      }.subscribe {

          aService.createContact(result, it)    

      }

[UPDATE] : I have resolved the issue with the following way :
```

employerService.getEmployee("Active") // return value is Mono<GetEmployeeStatusListResult>

.flatMapIterable(GetEmployeeStatusListResult::emps)

          .flatMap {

              employerService.getUsersById(it.userId).map{x->Pair(it,x)} // it is of type GetEmployeeStatusListResult.emps and  value returned from employerService.getUsersById(it.userId) is of type GetUserResult class created 

          }.subscribe {

              aService.createContact(it.first, it.second)    

          }

```

edited Jan 3 at 10:05

asked Jan 2 at 7:07

user10374449

114

1

I think it will help if you list the types returned by each of the variables. At some point an observable is not being returned and that could be the problem.

– Mahesh
Jan 2 at 7:11

@Mahesh edited the code snippet with comment for each line return type, assuming you are asking for this only

– user10374449
Jan 2 at 7:20

This is Kotlin, right? RxJS, as its name indicates, is a JavaScript library. Not a Kotlin or Java library. What you're using (Mono, Flux, etc.) are types from the Reactor library. Not from RxJS. Edit your question, change its title and text and remove the RxJS tag: RxJS has nothing to do with your code.

– JB Nizet
Jan 2 at 7:59

Thanks @JBNizet for correcting me !! Do you have any suggestions/advice for the above questions, Please share your expertise!!

– user10374449
Jan 2 at 8:34

add a comment |

Below is code snippet for more explanation

var result = employerService.getEmployee("Active") // return value is Mono<GetEmployeeStatusListResult>

result.flatMapIterable(GetEmployeeStatusListResult::emps)

      .flatMap {

          employerService.getUsersById(it.userId) // it is of type GetEmployeeStatusListResult.emps and  value returned from employerService.getUsersById(it.userId) is of type GetUserResult class created 

      }.subscribe {

          aService.createContact(result, it)    

      }

[UPDATE] : I have resolved the issue with the following way :
```

employerService.getEmployee("Active") // return value is Mono<GetEmployeeStatusListResult>

.flatMapIterable(GetEmployeeStatusListResult::emps)

          .flatMap {

              employerService.getUsersById(it.userId).map{x->Pair(it,x)} // it is of type GetEmployeeStatusListResult.emps and  value returned from employerService.getUsersById(it.userId) is of type GetUserResult class created 

          }.subscribe {

              aService.createContact(it.first, it.second)    

          }

```

edited Jan 3 at 10:05

asked Jan 2 at 7:07

user10374449

114

Below is code snippet for more explanation

var result = employerService.getEmployee("Active") // return value is Mono<GetEmployeeStatusListResult>

result.flatMapIterable(GetEmployeeStatusListResult::emps)

      .flatMap {

          employerService.getUsersById(it.userId) // it is of type GetEmployeeStatusListResult.emps and  value returned from employerService.getUsersById(it.userId) is of type GetUserResult class created 

      }.subscribe {

          aService.createContact(result, it)    

      }

[UPDATE] : I have resolved the issue with the following way :
```

employerService.getEmployee("Active") // return value is Mono<GetEmployeeStatusListResult>

.flatMapIterable(GetEmployeeStatusListResult::emps)

          .flatMap {

              employerService.getUsersById(it.userId).map{x->Pair(it,x)} // it is of type GetEmployeeStatusListResult.emps and  value returned from employerService.getUsersById(it.userId) is of type GetUserResult class created 

          }.subscribe {

              aService.createContact(it.first, it.second)    

          }

```

java kotlin reactive-programming project-reactor

edited Jan 3 at 10:05

asked Jan 2 at 7:07

user10374449

114

edited Jan 3 at 10:05

asked Jan 2 at 7:07

user10374449

114

edited Jan 3 at 10:05

asked Jan 2 at 7:07

user10374449

114

asked Jan 2 at 7:07

user10374449

114

asked Jan 2 at 7:07

user10374449

114

1

I think it will help if you list the types returned by each of the variables. At some point an observable is not being returned and that could be the problem.

– Mahesh
Jan 2 at 7:11

@Mahesh edited the code snippet with comment for each line return type, assuming you are asking for this only

– user10374449
Jan 2 at 7:20

This is Kotlin, right? RxJS, as its name indicates, is a JavaScript library. Not a Kotlin or Java library. What you're using (Mono, Flux, etc.) are types from the Reactor library. Not from RxJS. Edit your question, change its title and text and remove the RxJS tag: RxJS has nothing to do with your code.

– JB Nizet
Jan 2 at 7:59

Thanks @JBNizet for correcting me !! Do you have any suggestions/advice for the above questions, Please share your expertise!!

– user10374449
Jan 2 at 8:34

add a comment |

1

I think it will help if you list the types returned by each of the variables. At some point an observable is not being returned and that could be the problem.

– Mahesh
Jan 2 at 7:11

@Mahesh edited the code snippet with comment for each line return type, assuming you are asking for this only

– user10374449
Jan 2 at 7:20

This is Kotlin, right? RxJS, as its name indicates, is a JavaScript library. Not a Kotlin or Java library. What you're using (Mono, Flux, etc.) are types from the Reactor library. Not from RxJS. Edit your question, change its title and text and remove the RxJS tag: RxJS has nothing to do with your code.

– JB Nizet
Jan 2 at 7:59

Thanks @JBNizet for correcting me !! Do you have any suggestions/advice for the above questions, Please share your expertise!!

– user10374449
Jan 2 at 8:34

I think it will help if you list the types returned by each of the variables. At some point an observable is not being returned and that could be the problem.

– Mahesh
Jan 2 at 7:11

@Mahesh edited the code snippet with comment for each line return type, assuming you are asking for this only

– user10374449
Jan 2 at 7:20

This is Kotlin, right? RxJS, as its name indicates, is a JavaScript library. Not a Kotlin or Java library. What you're using (Mono, Flux, etc.) are types from the Reactor library. Not from RxJS. Edit your question, change its title and text and remove the RxJS tag: RxJS has nothing to do with your code.

– JB Nizet
Jan 2 at 7:59

Thanks @JBNizet for correcting me !! Do you have any suggestions/advice for the above questions, Please share your expertise!!

– user10374449
Jan 2 at 8:34

add a comment |

2 Answers
2

active

oldest

votes

It's a bit hard to know for sure from the information supplied above, but I think it looks like the call to employerService.getUsersById isn't returning a Publisher. From your comments I'm guessing it's returning an actual value, GetUserResult, rather than a Mono. Below is a mocked up set of classes which show the desired result, I believe. Maybe compare the below to what you've got and see if you can spot a difference?

data class Employee(val userId: String)

data class GetEmployeeStatusListResult(val emps: List<Employee>)

data class GetUserResult(val employee: Employee)



class EmployerService {

    fun getEmployee(status: String) = Mono.just(GetEmployeeStatusListResult(listOf(Employee("a"))))

    fun getUsersById(userId: String) = Mono.just(GetUserResult(Employee("a")))

}



fun test() {

    val employerService = EmployerService()

    employerService

            .getEmployee("Active")

            .flatMapIterable(GetEmployeeStatusListResult::emps)

            .flatMap {

                employerService.getUsersById(it.userId)

            }.subscribe {

                // Here "it" is a GetUserResult object

            }

}

If, in the subscribe, you need both the initial value retrieved from the call to getEmployee and also the result of the call to getUsersById then you could wrap those two values in a Pair as shown below:

employerService

        .getEmployee("Active")

        .flatMapIterable(GetEmployeeStatusListResult::emps)

        .flatMap { emp ->

            employerService.getUsersById(emp.userId).map { emp to it }

        }.subscribe {

            // Here "it" is a Pair<Employee, GetUserResult>

        }

edited Jan 2 at 9:25

answered Jan 2 at 9:15

Yoni Gibbs

1,418114

I have resolved this issue by adding Pair only but not in subscribe block but before that, I have updated the question with solution under UPDATE section. Thanks much !!

– user10374449
Jan 3 at 10:06

add a comment |

employerService.getEmployee("Active") // return value is Mono<GetEmployeeStatusListResult>

.flatMapIterable(GetEmployeeStatusListResult::emps)

          .flatMap {

              employerService.getUsersById(it.userId).map{x->Pair(it,x)} // it is of type GetEmployeeStatusListResult.emps and  value returned from employerService.getUsersById(it.userId) is of type GetUserResult class created 

          }.subscribe {

              aService.createContact(it.first, it.second)    

          }

Adding pair function to fetch both the values and use it in subscribe block !!
Thanks everyone !!

answered Jan 3 at 10:15

user10374449

114

add a comment |

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2 Answers
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active

oldest

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2 Answers
2

active

oldest

votes

data class Employee(val userId: String)

data class GetEmployeeStatusListResult(val emps: List<Employee>)

data class GetUserResult(val employee: Employee)



class EmployerService {

    fun getEmployee(status: String) = Mono.just(GetEmployeeStatusListResult(listOf(Employee("a"))))

    fun getUsersById(userId: String) = Mono.just(GetUserResult(Employee("a")))

}



fun test() {

    val employerService = EmployerService()

    employerService

            .getEmployee("Active")

            .flatMapIterable(GetEmployeeStatusListResult::emps)

            .flatMap {

                employerService.getUsersById(it.userId)

            }.subscribe {

                // Here "it" is a GetUserResult object

            }

}

employerService

        .getEmployee("Active")

        .flatMapIterable(GetEmployeeStatusListResult::emps)

        .flatMap { emp ->

            employerService.getUsersById(emp.userId).map { emp to it }

        }.subscribe {

            // Here "it" is a Pair<Employee, GetUserResult>

        }

edited Jan 2 at 9:25

answered Jan 2 at 9:15

Yoni Gibbs

1,418114

I have resolved this issue by adding Pair only but not in subscribe block but before that, I have updated the question with solution under UPDATE section. Thanks much !!

– user10374449
Jan 3 at 10:06

add a comment |

data class Employee(val userId: String)

data class GetEmployeeStatusListResult(val emps: List<Employee>)

data class GetUserResult(val employee: Employee)



class EmployerService {

    fun getEmployee(status: String) = Mono.just(GetEmployeeStatusListResult(listOf(Employee("a"))))

    fun getUsersById(userId: String) = Mono.just(GetUserResult(Employee("a")))

}



fun test() {

    val employerService = EmployerService()

    employerService

            .getEmployee("Active")

            .flatMapIterable(GetEmployeeStatusListResult::emps)

            .flatMap {

                employerService.getUsersById(it.userId)

            }.subscribe {

                // Here "it" is a GetUserResult object

            }

}

employerService

        .getEmployee("Active")

        .flatMapIterable(GetEmployeeStatusListResult::emps)

        .flatMap { emp ->

            employerService.getUsersById(emp.userId).map { emp to it }

        }.subscribe {

            // Here "it" is a Pair<Employee, GetUserResult>

        }

edited Jan 2 at 9:25

answered Jan 2 at 9:15

Yoni Gibbs

1,418114

I have resolved this issue by adding Pair only but not in subscribe block but before that, I have updated the question with solution under UPDATE section. Thanks much !!

– user10374449
Jan 3 at 10:06

add a comment |

data class Employee(val userId: String)

data class GetEmployeeStatusListResult(val emps: List<Employee>)

data class GetUserResult(val employee: Employee)



class EmployerService {

    fun getEmployee(status: String) = Mono.just(GetEmployeeStatusListResult(listOf(Employee("a"))))

    fun getUsersById(userId: String) = Mono.just(GetUserResult(Employee("a")))

}



fun test() {

    val employerService = EmployerService()

    employerService

            .getEmployee("Active")

            .flatMapIterable(GetEmployeeStatusListResult::emps)

            .flatMap {

                employerService.getUsersById(it.userId)

            }.subscribe {

                // Here "it" is a GetUserResult object

            }

}

employerService

        .getEmployee("Active")

        .flatMapIterable(GetEmployeeStatusListResult::emps)

        .flatMap { emp ->

            employerService.getUsersById(emp.userId).map { emp to it }

        }.subscribe {

            // Here "it" is a Pair<Employee, GetUserResult>

        }

edited Jan 2 at 9:25

answered Jan 2 at 9:15

Yoni Gibbs

1,418114

data class Employee(val userId: String)

data class GetEmployeeStatusListResult(val emps: List<Employee>)

data class GetUserResult(val employee: Employee)



class EmployerService {

    fun getEmployee(status: String) = Mono.just(GetEmployeeStatusListResult(listOf(Employee("a"))))

    fun getUsersById(userId: String) = Mono.just(GetUserResult(Employee("a")))

}



fun test() {

    val employerService = EmployerService()

    employerService

            .getEmployee("Active")

            .flatMapIterable(GetEmployeeStatusListResult::emps)

            .flatMap {

                employerService.getUsersById(it.userId)

            }.subscribe {

                // Here "it" is a GetUserResult object

            }

}

employerService

        .getEmployee("Active")

        .flatMapIterable(GetEmployeeStatusListResult::emps)

        .flatMap { emp ->

            employerService.getUsersById(emp.userId).map { emp to it }

        }.subscribe {

            // Here "it" is a Pair<Employee, GetUserResult>

        }

edited Jan 2 at 9:25

answered Jan 2 at 9:15

Yoni Gibbs

1,418114

edited Jan 2 at 9:25

answered Jan 2 at 9:15

Yoni Gibbs

1,418114

answered Jan 2 at 9:15

Yoni Gibbs

1,418114

answered Jan 2 at 9:15

Yoni Gibbs

1,418114

I have resolved this issue by adding Pair only but not in subscribe block but before that, I have updated the question with solution under UPDATE section. Thanks much !!

– user10374449
Jan 3 at 10:06

add a comment |

I have resolved this issue by adding Pair only but not in subscribe block but before that, I have updated the question with solution under UPDATE section. Thanks much !!

– user10374449
Jan 3 at 10:06

I have resolved this issue by adding Pair only but not in subscribe block but before that, I have updated the question with solution under UPDATE section. Thanks much !!

– user10374449
Jan 3 at 10:06

add a comment |

employerService.getEmployee("Active") // return value is Mono<GetEmployeeStatusListResult>

.flatMapIterable(GetEmployeeStatusListResult::emps)

          .flatMap {

              employerService.getUsersById(it.userId).map{x->Pair(it,x)} // it is of type GetEmployeeStatusListResult.emps and  value returned from employerService.getUsersById(it.userId) is of type GetUserResult class created 

          }.subscribe {

              aService.createContact(it.first, it.second)    

          }

Adding pair function to fetch both the values and use it in subscribe block !!
Thanks everyone !!

answered Jan 3 at 10:15

user10374449

114

add a comment |

employerService.getEmployee("Active") // return value is Mono<GetEmployeeStatusListResult>

.flatMapIterable(GetEmployeeStatusListResult::emps)

          .flatMap {

              employerService.getUsersById(it.userId).map{x->Pair(it,x)} // it is of type GetEmployeeStatusListResult.emps and  value returned from employerService.getUsersById(it.userId) is of type GetUserResult class created 

          }.subscribe {

              aService.createContact(it.first, it.second)    

          }

Adding pair function to fetch both the values and use it in subscribe block !!
Thanks everyone !!

answered Jan 3 at 10:15

user10374449

114

add a comment |

employerService.getEmployee("Active") // return value is Mono<GetEmployeeStatusListResult>

.flatMapIterable(GetEmployeeStatusListResult::emps)

          .flatMap {

              employerService.getUsersById(it.userId).map{x->Pair(it,x)} // it is of type GetEmployeeStatusListResult.emps and  value returned from employerService.getUsersById(it.userId) is of type GetUserResult class created 

          }.subscribe {

              aService.createContact(it.first, it.second)    

          }

Adding pair function to fetch both the values and use it in subscribe block !!
Thanks everyone !!

answered Jan 3 at 10:15

user10374449

114

employerService.getEmployee("Active") // return value is Mono<GetEmployeeStatusListResult>

.flatMapIterable(GetEmployeeStatusListResult::emps)

          .flatMap {

              employerService.getUsersById(it.userId).map{x->Pair(it,x)} // it is of type GetEmployeeStatusListResult.emps and  value returned from employerService.getUsersById(it.userId) is of type GetUserResult class created 

          }.subscribe {

              aService.createContact(it.first, it.second)    

          }

Adding pair function to fetch both the values and use it in subscribe block !!
Thanks everyone !!

answered Jan 3 at 10:15

user10374449

114

answered Jan 3 at 10:15

user10374449

114

answered Jan 3 at 10:15

user10374449

114

answered Jan 3 at 10:15

user10374449

114

add a comment |

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