javascript - How do I get data from two collections in firestore? - Stack Overflow

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I have the following problem. I try to manage a n to m structure with firebase. Therefore i made three collections. collections |-----cards |----name |----text |-----cardlist |----name |----numberOfCards |-----card_cardList |----cardId |----cardListId |----number

Now I have the id of a cardListand my goal is to get all the cards which are in this list. To get them from the card_list collection i made this collection('card_list', q => q.where('cardListId', '==', myId). After that i should somehow map the value number with the cards values which I need to get somehow.

Does anyone have a suggestion how to do this?

Edited: card_cardListis the collection which shows the n to m relation between cards and cardlist

I have the following problem. I try to manage a n to m structure with firebase. Therefore i made three collections. collections |-----cards |----name |----text |-----cardlist |----name |----numberOfCards |-----card_cardList |----cardId |----cardListId |----number

Now I have the id of a cardListand my goal is to get all the cards which are in this list. To get them from the card_list collection i made this collection('card_list', q => q.where('cardListId', '==', myId). After that i should somehow map the value number with the cards values which I need to get somehow.

Does anyone have a suggestion how to do this?

Edited: card_cardListis the collection which shows the n to m relation between cards and cardlist

• javascript
• typescript
• firebase
• google-cloud-firestore

Share Improve this question Follow edited Jan 10, 2019 at 7:44 Yingrjimsch asked Jan 10, 2019 at 7:12 YingrjimschYingrjimsch 12211 gold badge11 silver badge1111 bronze badges 4

• What different between cardlist and card_list? Your name of the collection already so confused – Tony Bui Commented Jan 10, 2019 at 7:22
• I'm sorry for that. the cardlist is a collection which contains the information of the list like what's it's name, how many cards does it contain etc. The card_list is the n to m table between a card and a cardlist whit their id and an additional property – Yingrjimsch Commented Jan 10, 2019 at 7:41
• So you want to get all the cards which are in this list in a single go? Please responde with @AlexMamo – Alex Mamo Commented Jan 10, 2019 at 7:51
• @AlexMamo yes thats the plan. I would like to get the card and the value number mapped. – Yingrjimsch Commented Jan 10, 2019 at 7:58

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According to the ments:

Q: So you want to get all the cards which are in this list in a single go?

A: Yes thats the plan.

You need to know that Firestore does not have any API to get documents from multiple collections in a single step. You will have to use two (or more) separate calls. In your particular case, you should create one to get the documents under cards collection, and another one to get the documents in the cardlist collection based on the relationship between them.

For more information, please also take a look at:

• Cloud Firestore - How to get relational data from two collections?

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