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问题描述
我有很多关系:
[人] x ------ 1 [人宠物] 1 ------ x [宠物]
[persons]x------1[personsPets]1------x[pets]
[persons]
id
name
[pets]
id
name
[personsPets]
id
personId
petId
使用@ angular/fire和rxjs 6,我想要一个服务来将人员阵列与宠物一起放置,就像这样:
Using @angular/fire and rxjs 6, I want a service to get the persons array with their pets each, like that:
this.personService.getPersons().subscribe(persons => {
const firstPersonPetNames: string[] = persons[0].pets.map(pet => pet.name)
const secondPersonPetNames: string[] = persons[1].pets.map(pet => pet.name)
console.log(firstPersonPetNames) // ['Copi Copi', 'Elemento', 'Adjetivo']
console.log(secondPersonPetNames) // ['James Bond', 'Chaucha', 'Yo no fui']
})
推荐答案
您可以这样构造它:
getPersonsWithPets() {
return this.getPersons().pipe( // get persons
switchMap(persons =>
// switch into combineLatest of persons mapped into their personPets fetch
combineLatest(persons.map(person => this.getPersonsPets(person.id).pipe(
switchMap(personPets =>
// switch again into combine latest of personPets mapped into pet fetch
combineLatest(personPets.map(personPet => this.getPet(personPet.petId))).pipe(
// map into the person with the pets assigned
map(pets => ({...person, pets}))
)
)))
)
);
}
可能通过将其分解一些来清理它:
possibly clean it up by breaking it down a little:
getFullPersonPets(personId) {
return this.getPersonsPets(personId).pipe( // get personPets
switchMap(personPets =>
// switch into combine latest of personPets mapped into pet fetch
combineLatest(personPets.map(personPet => this.getPet(personPet.petId)))
)
);
}
然后:
getPersonsWithPets() {
return this.getPersons().pipe( // get persons
switchMap(persons =>
// switch into combine latest of persons mapped into full pets fetch
combineLatest(persons.map(person => this.getFullPersonPets(person.id).pipe(
// map into the person with the pets assigned
map(pets => ({...person, pets}))
)))
)
);
}
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