Develop Reference

Firestore search across custom objects array

I try to make an app on Android for services reviews, every review is save like an element in the document "user" like this-
Everytime the user save a report I have see if inside the reports the field "plate" is existing comparing with the new one, I try query using the examples in the page arrays in Firebase
In the code i tried get with "whereEqualTo" method search by "reports.plate" or with the method "whereArrayContains" with the same field (the filter uid exits but in the first image doesn't show) any idea how i can search the document when some of the custom elements fields is equal
maybe sorry in advance for the english i'm practicing
Thanks in advance

How to do a simple search in string in Firebase database?

I want to create a simple search in my app, but cannot find anything on interwebs about it, that's more recent than 2014. There must be a better way. There are startAt and endAt functions but they don't work as expected and are case sensitive. How do you guys solve this problem? How can this functionality still not exist in 2016?

In my case I was able to partly achieve a SQL LIKE in the following way:
databaseReference.orderByChild('_searchLastName')
.startAt(queryText)
.endAt(queryText+"\uf8ff")
The character \uf8ff used in the query is a very high code point in the Unicode range (it is a Private Usage Area [PUA] code). Because it is after most regular characters in Unicode, the query matches all values that start with queryText.
In this way, searching by "Fre" I could get the records having "Fred, Freddy, Frey" as value in _searchLastName property from the database.

Create two String variables
searchInputToLower = inputText.getText().toString().toLowerCase();
searchInputTOUpper = inputText.getText().toString().toUpperCase();
Then in the Query set it to:
DatabaseReference reference = FirebaseDatabase.getInstance().getReference().child("Products");//Your firebase node you want to search inside..
FirebaseRecyclerOptions<Products> options =
new FirebaseRecyclerOptions.Builder<Products>()//the Products is a class that get and set Strings from Firebase Database.
.setQuery(reference.orderByChild("name").startAt(searchInputUpper).endAt(searchInputLower + "\uf8ff"),Products.class)
.build();
the "name" it's the node inside the Products Main Node.
the .startAt(searchInputUpper) & .endAt(searchInputLower + "\uf8ff") to make the search as contains all characters that typed in the inputText.getText() that you get.

finally I got it you can use where clause to get you result like SQL
LIKE keyword like% or %like
syntax :
Firestore.collection(collectionName).orderBy(field).where(field, ">=", keyword.toUpperCase()).where(field, "<=", keyword.toUpperCase() + "\uf8ff").get()

I my case used:
var query = 'text'
databaseReference.orderByChild('search_name')
.startAt(`%${query}%`)
.endAt(query+"\uf8ff")
.once("value")
In this way, searching by "test" I could get the records having "Test 1, Contest, One test" as value in 'search' property from the database.

Firebase is noSQL therefore it does not have searches built in like you'll find in SQL. You can either sort by values/key or you can equalto
https://firebase.google.com/docs/database/android/retrieve-data
You can find examples at the link above. That is the latest documentation for firebase.
If you are looking for SQL like searches. Then take a look at elastic search. But that will increase the complexity since you need a platform to put it on. For that i could recommend Heroku or maybe GoogleCloudServers
Here is a blog post about advanced searches with elastic search
https://firebase.googleblog.com/2014/01/queries-part-2-advanced-searches-with.html

This question might be old but there is a documented way of how to achieve this way, It is simple to implement. Quoted:
To enable full text search of your Cloud Firestore data, use a third-party search service like Algolia. Consider a note-taking app where each note is a document:
Algolia will be part of your firebase functions and will do all the searches you want.
// Update the search index every time a blog post is written.
exports.onNoteCreated = functions.firestore.document('notes/{noteId}').onCreate(event => {
// Get the note document
const note = event.data.data();
// Add an 'objectID' field which Algolia requires
note.objectID = event.params.noteId;
// Write to the algolia index
const index = client.initIndex(ALGOLIA_INDEX_NAME);
return index.saveObject(note);
});
To implement the search, the best way is to use instant search - android
Sample Search Image: GIF

The feature you're looking for is called full-text search and this is something most databases (including Firebase) don't provide out-of-the-box because it requires storing the data in a format that's optimized for text search (vs optimized for filtering) - these are two different problem sets with a different set of trade-offs.
So you would have to use a separate full-text search engine in conjunction with Firebase to be able to do this, especially if you need features like faceting, typo tolerance, merchandizing, etc.
You have a few options for a full-text search engine:
There's Algolia which is easy to get up and running but can get expensive quickly
There's ElasticSearch which has a steep learning curve but uber flexible
There's Typesense which aims to be an open source alternative to Algolia.

I don't know about the certainty of this approach but using the firebase version 10.2.6 on android, i get to do something like this:
firebaseDatabase.getReference("parent")
.orderByChild("childNode")
.startAt("[a-zA-Z0-9]*")
.endAt(searchString)
It seems to work well sometimes

Finally joined SO just to answer this.
For anyone coming here from/for the python firestore.client here's a solution that seems to work for me.
It's based on the accepted answer's concept but via the client rather than db.reference() and mixed with the answer from user12750908.
from firebase_admin import firestore
users = db.collection("users")\
.order_by("last_name")\
.where("last_name", ">=", last_name.upper())\
.where("last_name", "<=", last_name.lower() + "\uf8ff")\
.stream()
It works for the simple test I did, but I'll update my answer if I have issues with it later. And just a reminder, this is similar to
LIKE search%
and not
LIKE %search%.
Edit 1
I didn't see any tags for the question, but the title attribute mentions Android so this may not necessarily answer the question directly, but if you have a python API, this should work. I'm unfortunately not sure if there's an equivalent client/db separation in the Android version like there is in the Firebase Admin for Python. I didn't want to delete the answer since I hadn't seen any answers for firestore client during my search for a similar answer and hope it helps anyone else stumbling around.
Edit 09-03-2020 This works a portion of the time it seems. Most of the time I didn't seem to have an issue, but when I applied it to another project I was getting unexpected results. Long story short you may need to replicate how you save the data you're comparing against. For example, you may need to have a field to save the last_name in all caps and another field to save it in all lowercase, then you change the first where clause to compare last_name_upper and the second to compare last_name_lowercase. In my second project so far this seems to yield more accurate results so you may want to give that a try if the previous answer doesn't work well
EDIT 09-07-2020 Previous edit from 09-03-2020 is partially accurate. During my haste of thinking I had it fully resolved I completely forgot firebase doesn't let you use <, >, <=, >= across different fields. You may need to do two queries and merge them, but you'd probably still be reading more docs than you really intend. Doing the comparison against either the upper or lower version with the appropriate search term seems to give the original results expected from the original answer. For example:
.orderBy("last_name_upper")
.where("last_name_upper", ">=", this.searchForm.text.toUpperCase())
.where("last_name_upper", "<=", this.searchForm.text.toUpperCase() + "\uf8ff")

As firebase documentation, firebase doesn't support full text search.
But to do that you can use third-party tools.
Check this link to learn more https://firebase.google.com/docs/firestore/solutions/search

Filter url JSON results using App Inventor 2

I'm trying to filter a JSON url results using App Inventor 2, following sample codes from here1 and here2, but I still cannot get it done right. I only get one result at a time.
The JSON results are data in the form shown in the following figure:
{
"field1":"alphaNumeric1",
"field2":"aNumber1",
"field3":"DD/MM/YY",
"field4":"HH/MM/SS",
"field5":"https://",
"field6":"aText",
"field7":"aNumber2",
"field8":"alphaNumeric2",
"field9":"aNumber3",
"field10":"alphaNumeric3"
}
The JSON url is constantly updated, so are the results, but this is not a problem for now. I can get it read by a timer.
The problem is that from the above results, I need to parse "field2", "field5", "field6", in according labels in the app.
So e.g., when I input a "aNumber1" to get searched in the JSON data, and have the result in a label.
Is it possible this JSON data search be done with App Inventor 2?
Anyone kind enough please answer with a sample blocks if possible.
Thank you all in advance!
[EDIT 1]
No matter what I've tried, JSON could not get filtered right. Therefore I'm to filter the url results in XML.
The XML results are data in the form shown in the following figure:
<results>
<decision>
<alphaNumeric1>ABC1D</alphaNumeric1>
<aNumber1>ABCD</aNumber1>
<aDate>123</aDate>
<doc>HTTP</doc>
<aNumber2>1234</aNumber2>
<alphaNumeric2>TYPE</talphaNumeric2>
<aNumber3>12345</aNumber3>
<aNumber4>1234567</aNumber4>
<aText>SomeText</aText>
<aHour>00:00:00</aHour>
</decision>
.
.
.
<decision>
.
.
.
</decision>
.
.
.
</results>
I have tried to follow the example at here2, but I don't get it right. According to the XML output, what should I put in starTag and endTag, to get a parsing result if I'm searching for e.g. aNumber4 value (= 1234567) ?
Can someone respond with an answer?
[EDIT 2]
Well I'm trying to make some progress here following the example at here3.
The XML is being parsed with a runtime error "this is not a well formatted list of pairs".
Following is the blocks code I'm using:
Why is that so, since I'm following the example to the letter? Any clues anyone to solve this out?

well, your blocks look a little bit strange...
you have a complex list of lists, just use Do it to find out, how it looks like after each step of using lookup in pairs...
It helps to follow the already provided links:
how to work with lists
how to work with list of lists (pdf) by appinventor.org
see also An example of a complex List of Lists
In the example blocks below I looked for the first <decision> and displayed the value of tag aDate in Label1 like this
you might want to loop through the different <decision>s using a for each in list loop....

How to fetch more than 4 results google json feed load api?

Currently when I call google rss/atom feed loader, I always get only 4 results in the response.
How can I get all the items in the response?
I need the results for my android app.
'https://ajax.googleapis.com/ajax/services/feed/load?v=1.0&q=http://www.digg.com/rss/index.xml'

I got the answer. I just need to add a "num" parameter to my query
https://ajax.googleapis.com/ajax/services/feed/load?v=1.0&q=http://www.digg.com/rss/index.xml&num=30

The 'num' parameter does not work for 'find' method it only works for 'load' method. So I don't think there is any solution to this problem.

Use feed.setNumEntries(7); for retrieving more than 4 entries or number of items you want to retrieve.
var feed = new google.feeds.Feed("http://www.wsj.com/xml/rss/3_7085.xml");
feed.setNumEntries(7);
Read more: Google Feed API Developer's Guide

How to link many objects to a singular object in Parse.com

I am making an android application that uses Parse.com as its server backend.I want to enable users to post comments to poems uploaded but am stuck on how to link many comments to a particular poem Object.Does anyone have an idea of how to do that?Any help will be appreciated.

You create the comment as an instance of class=comment that is separate from the Poem instance, saving the object ID that parse returns on 'insert comment'.
Then, as a child of Poem object, you have 'comments' attribute under which you insert ArrayType pointer to the ID returned by the previous insert to the comment class.
'{"comments":{"__op":"Add","objects":[{"__type":"Pointer",
"className":"Comment","objectId":"$returnValueOfCommentInsert"}]}}'
The pointer type entity is added (ptrToComment) is added to an array of pointers sitting in 'comments' entity inside Poem object.
This assumes use of Rest API.

Reading the documentation is a good start. How about the section on Andriod Relational Data?