Increment a Firestore document field
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Update a Firestore document field using Increment. If a field doesn't exist, Firestore creates the field, and then increments it.
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For detailed documentation that includes this code sample, see the following:
Code sample
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[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],[],[[["\u003cp\u003eFirestore's \u003ccode\u003eIncrement\u003c/code\u003e can update a document field, adding the field if it does not already exist.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eIncrement\u003c/code\u003e function atomically modifies a field's value, such as increasing a city's population by a set number.\u003c/p\u003e\n"],["\u003cp\u003eAuthentication for Firestore operations requires setting up Application Default Credentials.\u003c/p\u003e\n"],["\u003cp\u003eThe provided code samples illustrate how to use \u003ccode\u003eIncrement\u003c/code\u003e across different programming languages, including C#, Go, Java, Node.js, PHP, Python, and Ruby.\u003c/p\u003e\n"]]],[],null,["# Increment a Firestore document field\n\nUpdate a Firestore document field using Increment. If a field doesn't exist, Firestore creates the field, and then increments it.\n\nExplore further\n---------------\n\n\nFor detailed documentation that includes this code sample, see the following:\n\n- [Add and update data](/firestore/native/docs/manage-data/add-data)\n- [Add data to Cloud Firestore](https://firebase.google.com/docs/firestore/manage-data/add-data)\n\nCode sample\n-----------\n\n### C#\n\n\nTo authenticate to Firestore, set up Application Default Credentials.\nFor more information, see\n\n[Set up authentication for a local development environment](/docs/authentication/set-up-adc-local-dev-environment).\n\n DocumentReference washingtonRef = db.Collection(\"cities\").Document(\"DC\");\n\n // Atomically increment the population of the city by 50.\n await washingtonRef.UpdateAsync(\"Regions\", FieldValue.Increment(50));\n\n### Go\n\n\nTo authenticate to Firestore, set up Application Default Credentials.\nFor more information, see\n\n[Set up authentication for a local development environment](/docs/authentication/set-up-adc-local-dev-environment).\n\n import (\n \t\"context\"\n \t\"fmt\"\n\n \t\"cloud.google.com/go/firestore\"\n )\n\n // updateDocumentIncrement increments the population of the city document in the\n // cities collection by 50.\n func updateDocumentIncrement(projectID, city string) error {\n \t// projectID := \"my-project\"\n\n \tctx := context.Background()\n\n \tclient, err := firestore.NewClient(ctx, projectID)\n \tif err != nil {\n \t\treturn fmt.Errorf(\"firestore.NewClient: %w\", err)\n \t}\n \tdefer client.Close()\n\n \tdc := client.Collection(\"cities\").Doc(city)\n \t_, err = dc.Update(ctx, []firestore.Update{\n \t\t{Path: \"population\", Value: firestore.https://cloud.google.com/go/docs/reference/cloud.google.com/go/firestore/latest/index.html#cloud_google_com_go_firestore_Increment(50)},\n \t})\n \tif err != nil {\n \t\treturn fmt.Errorf(\"Update: %w\", err)\n \t}\n\n \treturn nil\n }\n\n### Java\n\n\nTo authenticate to Firestore, set up Application Default Credentials.\nFor more information, see\n\n[Set up authentication for a local development environment](/docs/authentication/set-up-adc-local-dev-environment).\n\n DocumentReference washingtonRef = db.collection(\"cities\").document(\"DC\");\n\n // Atomically increment the population of the city by 50.\n final ApiFuture\u003cWriteResult\u003e updateFuture =\n washingtonRef.update(\"population\", FieldValue.increment(50));\n\n### Node.js\n\n\nTo authenticate to Firestore, set up Application Default Credentials.\nFor more information, see\n\n[Set up authentication for a local development environment](/docs/authentication/set-up-adc-local-dev-environment).\n\n // ...\n const washingtonRef = db.collection('cities').doc('DC');\n\n // Atomically increment the population of the city by 50.\n const res = await washingtonRef.update({\n population: FieldValue.increment(50)\n });\n\n### PHP\n\n\nTo authenticate to Firestore, set up Application Default Credentials.\nFor more information, see\n\n[Set up authentication for a local development environment](/docs/authentication/set-up-adc-local-dev-environment).\n\n $cityRef = $db-\u003ecollection('samples/php/cities')-\u003edocument('DC');\n\n // Atomically increment the population of the city by 50.\n $cityRef-\u003eupdate([\n ['path' =\u003e 'regions', 'value' =\u003e FieldValue::increment(50)]\n ]);\n\n### Python\n\n\nTo authenticate to Firestore, set up Application Default Credentials.\nFor more information, see\n\n[Set up authentication for a local development environment](/docs/authentication/set-up-adc-local-dev-environment).\n\n washington_ref = db.collection(\"cities\").document(\"DC\")\n\n washington_ref.update({\"population\": firestore.Increment(50)})\n\n### Ruby\n\n\nTo authenticate to Firestore, set up Application Default Credentials.\nFor more information, see\n\n[Set up authentication for a local development environment](/docs/authentication/set-up-adc-local-dev-environment).\n\n city_ref = firestore.doc \"#{collection_path}/DC\"\n city_ref.update({ population: firestore.field_increment(50) })\n\nWhat's next\n-----------\n\n\nTo search and filter code samples for other Google Cloud products, see the\n[Google Cloud sample browser](/docs/samples?product=firestore)."]]