Cloud Firestore provides powerful query functionality for specifying which documents you want to retrieve from a collection or collection group. After creating a query object, use the get function to retrieve the results:.

See Get Data for more information on retrieving query results. You can also add a listener to a query to get the current results and listen for future updates. The where method takes three parameters: a field to filter on, a comparison operation, and a value. For iOS, Android, and Java, the comparison operator is explicitly named in the method. You can use the array-contains operator to filter based on array values.

For example:. If the array has multiple instances of the value you query on, the document is included in the results panhead electronic ignition once. An in query returns documents where the given field matches any of the comparison values. This query returns every city document where the country field is set to USA or Japan.

Similarly, use the array-contains-any operator to combine up to 10 array-contains clauses on the same field with a logical OR. An array-contains-any query returns documents where the given field is an array that contains one or more of the comparison values:.

Results from array-contains-any are de-duped. Even if a document's array field matches more than one of the comparison values, the result set includes that document only once. Note the following limitations for in and array-contains-any :. You can also chain multiple where methods to create more specific queries logical AND.

A collection group consists of all collections with the same ID. By default, queries retrieve results from a single collection in your database. Use a collection group query to retrieve documents from a collection group instead of from a single collection.

For example, you can create a landmarks collection group by adding a landmarks subcollection to each city:. We can use the simple and compound query described earlier to query a single city's landmarks subcollection, but you might also want to retrieve results from every city's landmarks subcollection at once. The landmarks collection group consists of all collections with the ID landmarksand you can query it using a collection group query. For example, this collection group query retrieves all museum landmarks across all cities:.

Before using a collection group query, you must create an index that supports your collection group query. You can create an index through an error message, the console, or the Firebase CLI. For the web and mobile SDKs, you must also create rules that allow your collection group queries. Cloud Firestore either does not support or provides limited support for the following types of queries:. Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.

For details, see the Google Developers Site Policies. Guides Get started with Firebase. Add Firebase to an app. Add Firebase to a game. Use Firebase with a framework.A while ago, Google has released Cloud Firestore. In this article I want to tell how to start using it. Cloud Firestore allows you to store data on a remote server, easily get access to them and monitor changes in real time.

The documentation has an excellent comparison of Cloud Firestore and Realtime Database. In the Firebase console, select Database and click on Create database. Next, select the access settings. You can read more about access modes here.

To configure the project, we have to make the following steps:. To get acquainted with the basic techniques of working with Cloud Firestore, I made a simple application.

The source code for the app can be found here:. To make the application work you need to create a project in the Firebase console and add the google-services. Firestore uses collections and documents to store data. A document is an entry that contains any fields. Documents are combined into collections. Also, the document may contain nested collections, but on Android it is not supported.

If we draw an analogy with the SQL database, the collection is a table, and the document is an entry in this table.

Getting data

One collection may contain documents with a different set of fields. In order to get all the documents of a collection, the following code is enough. Here we request all documents from the Tasks collection. The library allows you to create queries with parameters. The following code shows how to get documents from the collection by condition. Here we request all documents from the Tasks collection, in which the title field corresponds to the value of Task1.

While getting the documents, they can be immediately converted into our data classes. For writing, you have to create a Hashmap with data where the name of the field acts as a key, and the value of this field as a value and transfer it to the library. You can see that in the following code. In this example, a new document will be created and the Firestore will generate an id for it. To set your own id you need to do the following. In this case, if there is no document with id equal to New taskthen it will be created, and if it is, then the specified fields will be updated.

Firestore allows you to subscribe to data changes. You can subscribe to changes in the collection as well as changes to a specific document. Each object contains a modified document and a type of change. Realtime Database provides more or less convenient mechanism for loading large amounts of data, which based on manually editing a json file and loading it.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I have a static method that gets all the documents in a collection.

I am having trouble creating an array of these documents to return. How could I do that? Let us call the Array list 'allItems'. My approach was to add each item that is created inside the for loop to an the allItems array list, but this list is null when I return it and android studio is prompting me to make the array list final. There's nothing wrong with making it final, and given that code, it's impossible for it to return null, but very possibly might be emptybecause it's actually returning before Firebase even attempts to make a remote database query.

That's the problem with being asynchronous - you need to wait for the result before you can return it. From there, refactor the rest of the code to pass in the listener you've already written rather than actually expect an object to be returned from the method call.

Learn more. How to get all documents from a firestore collection and return them in an array list?

Get data with Cloud Firestore

Asked 1 year, 4 months ago. Active 1 year, 4 months ago. Viewed 3k times. Oamar Kanji Oamar Kanji 1 1 gold badge 9 9 silver badges 19 19 bronze badges. Active Oldest Votes. From there, refactor the rest of the code to pass in the listener you've already written rather than actually expect an object to be returned from the method call API. I write it in Kotlin, so please adapt this in your code. Hello World Hello World 2 2 silver badges 13 13 bronze badges.

Thank you, I am having trouble understanding this though. How will this allow me to return an array list with the documents?There are two ways to retrieve data stored in Cloud Firestore. Either of these methods can be used with documents, collections of documents, or the results of queries:.

When you set a listener, Cloud Firestore sends your listener an initial snapshot of the data, and then another snapshot each time the document changes. The following example shows how to retrieve the contents of a single document using get :.

firestore get all documents in collection android

For platforms with offline support, you can set the source option to control how a get call uses the offline cache. By default, a get call will attempt to fetch the latest document snapshot from your database. On platforms with offline support, the client library will use the offline cache if the network is unavailable or if the request times out.

You can specify the source option in a get call to change the default behavior. You can fetch from only the database and ignore the offline cache, or you can fetch from only the offline cache. For example:. The previous example retrieved the contents of the document as a map, but in some languages it's often more convenient to use a custom object type. In Add Datayou defined a City class that you used to define each city.

You can turn your document back into a City object:. To use custom objects, you must define a FirestoreDataConverter function for your class. To support automatic type serialization in Swift, your type must conform to the Codable protocol. Important: Each custom class must have a public constructor that takes no arguments. In addition, the class must include a public getter for each property.

Each custom class must have a public constructor that takes no arguments. You can also retrieve multiple documents with one request by querying documents in a collection.

For example, you can use where to query for all of the documents that meet a certain condition, then use get to retrieve the results:. By default, Cloud Firestore retrieves all documents that satisfy the query in ascending order by document ID, but you can order and limit the data returned.

In addition, you can retrieve all documents in a collection by omitting the where filter entirely:. A collection group consists of all collections with the same ID. For example, if each document in your cities collection has a subcollection called landmarksall of the landmarks subcollections belong to the same collection group. By default, queries retrieve results from a single collection in your database.

Use a collection group query to retrieve results from a collection group instead of from a single collection. The getCollections method of the Cloud Firestore server client libraries lists all subcollections of a document reference. You should only look up collection names as part of administrative tasks in trusted server environments. Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.

For details, see the Google Developers Site Policies. Overview Guides Reference Samples Libraries. Guides Get started with Firebase. Add Firebase to an app. Add Firebase to a game. Use Firebase with a framework. Manage your Firebase projects. Manage projects programmatically.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I have a static method that gets all the documents in a collection. I am having trouble creating an array of these documents to return. How could I do that? Let us call the Array list 'allItems'. My approach was to add each item that is created inside the for loop to an the allItems array list, but this list is null when I return it and android studio is prompting me to make the array list final.

There's nothing wrong with making it final, and given that code, it's impossible for it to return null, but very possibly might be emptybecause it's actually returning before Firebase even attempts to make a remote database query.

That's the problem with being asynchronous - you need to wait for the result before you can return it. From there, refactor the rest of the code to pass in the listener you've already written rather than actually expect an object to be returned from the method call.

How are we doing? Please help us improve Stack Overflow. Take our short survey. Learn more. How to get all documents from a firestore collection and return them in an array list?

Asked 1 year, 4 months ago. Active 1 year, 4 months ago. Viewed 3k times. Oamar Kanji Oamar Kanji 1 1 gold badge 9 9 silver badges 19 19 bronze badges. Active Oldest Votes. From there, refactor the rest of the code to pass in the listener you've already written rather than actually expect an object to be returned from the method call API. I write it in Kotlin, so please adapt this in your code. Hello World Hello World 2 2 silver badges 13 13 bronze badges.

Thank you, I am having trouble understanding this though. How will this allow me to return an array list with the documents? I already edit my code, so please check it again.

If you still use for-loop then return it after for-loop. By the way, please careful when you use your allItems.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information.

Tried most of the answers but none worked out. Is there any way to query data in this structure? The docs only available for normal array. Not available for array of custom object. With your current document structure, it's not possible to perform the query you want. Firestore does not allow queries for individual fields of objects in list fields. What you would have to do is create an additional field in your document that is queryable.

For example, you could create a list field with only the list of string languages that are part of the document. With this, you could use an array-contains query to find the documents where a language is mentioned at least once. For the document shown in your screenshot, you would have a list field called "languages" with values ["Swift", "Kotlin"]. Actually it is possible to perform such a query when having a database structure like yours.

I have replicated your schema and here are document1document2and document3. Note that you cannot query using partial incomplete data. You are using only the lang property to query, which is not correct. You should use an object that contains both properties, lang and years. Seeing your screenshot, at first glance, the experience array is a list of HashMap objects. But here comes the nicest part, that list can be simply mapped into a list of custom objects.

Let's try to map each object from the array to an object of type Experience. The model contains only two properties:. I don't know how you named the class that represents a document, but I named it simply Job.

To keep it simple, I have only used two properties:. Now, to perform a search for all documents that contain in the array an object with the lang set to Swiftplease follow the next steps.

First, create a new object of the Experience class:. The result in the logcat will be the name of document1 and document2 :. And this is because only those two documents contain in the array an object where the lang is set to Swift. So there is no need to duplicate data in this use-case. I have also written an article on the same topic. That's correct, it only searches for one element.

However, if you need to query for more than that:. We use another approach, which is actually very simple. I'm talking about Query's whereArrayContainsAny method:. Creates and returns a new Query with the additional filter that documents must contain the specified field, the value must be an array, and that the array must contain at least one value from the provided list.

Why am I talking about duplicating data in a document it's because the documents have limits. So there are some limits when it comes to how much data you can put into a document.

According to the official documentation regarding usage and limits :.

firestore get all documents in collection android

As you can see, you are limited to 1 MiB total of data in a single document.There are two ways to retrieve data stored in Cloud Firestore. Either of these methods can be used with documents, collections of documents, or the results of queries:.

When you set a listener, Cloud Firestore sends your listener an initial snapshot of the data, and then another snapshot each time the document changes. The following example shows how to retrieve the contents of a single document using get :. For platforms with offline support, you can set the source option to control how a get call uses the offline cache.

By default, a get call will attempt to fetch the latest document snapshot from your database.

Add a collection to a document in Firebase Cloud Firestore

On platforms with offline support, the client library will use the offline cache if the network is unavailable or if the request times out. You can specify the source option in a get call to change the default behavior.

firestore get all documents in collection android

You can fetch from only the database and ignore the offline cache, or you can fetch from only the offline cache. For example:. The previous example retrieved the contents of the document as a map, but in some languages it's often more convenient to use a custom object type. In Add Datayou defined a City class that you used to define each city. You can turn your document back into a City object:.

To use custom objects, you must define a FirestoreDataConverter function for your class. To support automatic type serialization in Swift, your type must conform to the Codable protocol. Important: Each custom class must have a public constructor that takes no arguments. In addition, the class must include a public getter for each property.

Each custom class must have a public constructor that takes no arguments. You can also retrieve multiple documents with one request by querying documents in a collection.

For example, you can use where to query for all of the documents that meet a certain condition, then use get to retrieve the results:. By default, Cloud Firestore retrieves all documents that satisfy the query in ascending order by document ID, but you can order and limit the data returned. In addition, you can retrieve all documents in a collection by omitting the where filter entirely:. A collection group consists of all collections with the same ID.

For example, if each document in your cities collection has a subcollection called landmarksall of the landmarks subcollections belong to the same collection group. By default, queries retrieve results from a single collection in your database.

Use a collection group query to retrieve results from a collection group instead of from a single collection. The getCollections method of the Cloud Firestore server client libraries lists all subcollections of a document reference.

You should only look up collection names as part of administrative tasks in trusted server environments. Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4. For details, see the Google Developers Site Policies. Why Google close Groundbreaking solutions.

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