Get all documents from collection where ID contains certain ref

Question

Is it possible to get all documents where the ID contains a certain value. I'm using Angular 7.

I tried db.collection('items').where.. but this is not supported.

Example

(collection)
/items
     (doc)
     /green apple
     /red apple
     /banana
     /melon

Can I do a query on the collection 'items' to retrieve all the docs where the ID contains 'apple'. I can't seem to find a working solution.

Are you saying you just want to fetch the document by its unique id? No need for a query to do that. — Doug Stevenson, Dec 12 '18 at 19:42
I'd defer to @DougStevenson, but my suggestion would be to create a field in the doc that matches the name (and probably skip the custom names in favor of google-generated gibberish), then query on that name-field value. — danh, Dec 12 '18 at 19:46
@danh The "gibberish", as you say, is actually important when you don't have a uniquely identifiable string to represent a document. You use it when you need it, but there's no obligation if you already have a unique id. That said, coming up with unique strings is not always that easy or convenient. — Doug Stevenson, Dec 12 '18 at 19:49
Thanks @DougStevenson. I didn’t mean gibberish in a pejorative sense, more whimsically to refer to system generated unique id. I think the op really needs a field for query, rather than (or in addition to) a readable name. — danh, Dec 12 '18 at 19:52
Firestore allow prefix-matching, but does not have a "contains" operator. So unless "apple" is at the start, what you're looking for is not possible with a query. See https://stackoverflow.com/questions/47115422/is-there-a-way-to-search-sub-string-at-firestore — Frank van Puffelen, Dec 12 '18 at 19:59
@DougStevenson I want to fetch all the docs that match the contains. I'm not using the auto ID for the doc, since I wanted unique docs so they get updated or skipped if a new doc came with that ID. — rafbanaan, Dec 13 '18 at 07:40

score 0 · Answer 1 · answered Dec 12 '18 at 22:03

Here's what I'd do: When creating (or updating) the doc, use the string that you would have used as the title to create another property, maybe call it searchTerms:

let docName = 'green apple';
let ref = /* some path */.collection('items').doc();  // optionally use docName here
let doc = { /* however you initialize your doc */ }

doc.searchTerms = docName.split(' ').reduce((acc, term) => {
      acc[term] = true;
      return acc;
    }, {});
    // that will set searchTerms to { 'green':true, 'apple':true }

ref.set(doc)

Later, you can query those docs like this:

let targetTerm = 'apple'
let key = `searchTerms.${targetTerm}`;
let query = /* some path */.collection('items').where(key, '==', true)

In August, the product introduced support for searching arrays, so you can skip the reduce when creating the object, and ask where-contains on the query, like this:

// as before
doc.searchTerms = docName.split(' ');
ref.set(doc)

and later:

let targetTerm = 'apple'
let query = /* some path */.collection('items').where('searchTerms', 'array-contains', targetTerm)

You might also use a cloud trigger onCreate to build the search terms field, so all the points in code where creation is done can not worry about this.

Get all documents from collection where ID contains certain ref

1 Answers1