我有一个包含人和宠物的 Firestore 数据库,宠物有所有者 ID。
//集合/文档ID:{data}
persons / 'person1': { name: 'Romea' }
persons / 'person2': { name: 'Julieto' }
pets / 'pet1': { name: 'Forky', ownerID: 'person1' }
pets / 'pet2': { name: 'Rasky', ownerID: 'person1' }
pets / 'pet3': { name: 'Tursy', ownerID: 'person2' }
因此,当 Julieto 拥有 Tursky 时,Romea 拥有 Forky 和 Rasky。
我正在使用@angular/fire,并且我想使用最新版本的 rxjs (6.5.x) 来获取用户与宠物的可观察值列表每个,参见以下结构:
[
0: {
name: 'Romea',
pets: [ 0: { name: 'Forky', ownerID: 'person1' }, 1: { name: 'Rasky', ownerID: 'person1' } ]
},
1: {
name: 'Julieto',
pets: [ 0: { name: 'Tursky', ownerID: 'person2' } ]
}
]
毕竟,我想调用 person.pets,如下所示:
this.personService.getPersonsWithPets().subscribe(persons => {
console.log(persons[0].pets)
// result: [{ name: 'Forky', ownerID: 'person1' }, { name: 'Rasky', ownerID: 'person1' }]
persons.forEach(person => person.pets.forEach(pet => console.log(pet.name)))
// result: 'Forky', 'Rasky', 'Tursky'
})
解决方案
根据@bryan60的解决方案,这就是我所做的(rxjs加上一个在构造函数中接收人和宠物的类):
服务:
private personsCollection: AngularFirestoreCollection<Person> = this.db.collection<Person>('persons')
private _getPersonsWithoutPets(): Observable<Person[]> {
return this.personsCollection.valueChanges()
}
getPersons(): Observable<(Person)[]> {
return this._getPersonsWithoutPets().pipe(
switchMap(persons => {
return combineLatest(persons.map(person => this.getPersonPets(person.id).pipe(
map(pets => new Person(person, pets))
)))
})
)
}
getPersonPets(personId: string): Observable<Pet[]> {
return this.db.collection<Pet>('pets', ref => ref.where('personId', '==', personId)).valueChanges()
}
型号:
export class Person {
id?: string
name: string
public constructor(person: Person = null, private pets: Pet[] = null) {
Object.assign(this, person)
this.pets = pets
}
model?() {
return {
id: this.id,
name: this.name
}
}
}
export class Pet {
id?: string
name: string
constructor(pet: Pet = null) {
Object.assign(this, pet)
}
model?() {
return {
id: this.id,
name: this.name
}
}
}
组件:
personsWithPets: Person[] = []
constructor(private personService: PersonService) {
this.getPersons()
}
getPersons() {
this.personService.getPersons().subscribe(p => this.personsWithPets = p)
}
针对人员有多个引用对象(宠物、汽车)的情况的解决方案:
getPersonsWithReferences(): Observable<Person[]> {
return this.getPersons().pipe(switchMap(persons =>
combineLatest(persons.map(person =>
combineLatest(this.getPersonPets(person.id), this.getPersonCars(person.id))
.pipe(map(([pets, cars]) => new Environment(person, pets, cars)))))))
}
最佳答案
这是一个 switchMap 用例。
假设您有函数 getPersons()
和 getPersonsPets(ownerID)
,它们执行其名称所暗示的操作,请执行以下操作:
getPersonsWithPets() {
return this.getPersons().pipe(
switchMap(persons => {
return combineLatest(persons.map(person => this.getPersonsPets(person.id).pipe(
map(pets => Object.assign(person, {pets}))
)))
})
)
}
首先获取人员,switchMap 到将人员映射到他们的宠物流中的combineLatest,并将宠物分配给人员,然后返回人员及其宠物的列表。
有更多作业:
getPersonsWithPets() {
return this.getPersons().pipe(
switchMap(persons => {
return combineLatest(persons.map(person =>
combineLatest(
this.getPersonsPets(person.id),
this.getPersonsCars(person.id),
this.getPersonsHouses(person.id)
).pipe(
map(([pets, cars, houses]) => Object.assign(person, {pets, cars, houses}))
)
))
})
)
}
关于angular - 从 id 与 rxjs Angular Firestore 合并可观察值,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/58961381/