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Patching: How to Perform Single Document Patch Operations

The Patch operation is used to perform partial document updates without having to load, modify, and save a full document. The whole operation is executed on the server-side and is useful as a performance enhancement or for updating denormalized data in entities.

The current page deals with patch operations on single documents.

Patching has three possible interfaces: Session API, Session API using defer, and Operations API.

In this page:
API overview
Examples

API overview

Session API

A session interface that allows performing the most common patch operations.
The patch request will be sent to server only after the call to saveChanges, this way it's possible to perform multiple operations in one request to the server.

Increment Field Value

session.advanced().increment

<T, U> void increment(String id, String path, U valueToAdd);

<T, U> void increment(T entity, String path, U valueToAdd);

Parameters
T Class Entity class
U Class Field class, must be of numeric type, or a String of char for string concatenation
entity T Entity on which the operation should be performed. The entity should be one that was returned by the current session in a load or query operation, this way, the session can track down the entity's ID
entity id String Entity ID on which the operation should be performed.
delta U Value to be added.

Set Field Value

session.advanced().patch

<T, U> void patch(String id, String path, U value);

<T, U> void patch(T entity, String path, U value);

Parameters
T Class Entity Class
U Class Field class
entity T Entity on which the operation should be performed. The entity should be one that was returned by the current session in a load or query operation, this way, the session can track down the entity's ID
entity id String Entity ID on which the operation should be performed.
delta U Value to set.

Array Manipulation

session.advanced().patch

<T, U> void patch(T entity, String pathToArray, Consumer<JavaScriptArray<U>> arrayAdder);

<T, U> void patch(String id, String pathToArray, Consumer<JavaScriptArray<U>> arrayAdder);

Parameters
T Class Entity class
U Class Field class
entity T Entity on which the operation should be performed. The entity should be one that was returned by the current session in a Load or Query operation, this way, the session can track down the entity's ID
entity id String Entity ID on which the operation should be performed.
arrayAdder Consumer<JavaScriptArray<U>> Lambda that modifies the array, see JavaScriptArray below.

JavaScriptArray

JavaScriptArray allows building lambdas representing array manipulations for patches.

Method Signature Return Type Description
put(T item) JavaScriptArray Allows adding item to an array.
put(T... items) JavaScriptArray Items to be added to the array.
put(Collection items) JavaScriptArray Items to be added to the array.
removeAt(int index) JavaScriptArray Removes item in position index in array.

Session API using defer

The low level session api for patches uses the session.advanced().defer function that allows registering single or several commands.
One of the possible commands is the PatchCommandData, describing single document patch command.
The patch request will be sent to server only after the call to saveChanges, this way it's possible to perform multiple operations in one request to the server.

session.advanced().defer

void defer(ICommandData[] commands);

PatchCommandData

Constructor
id String ID of the document to be patched.
changeVector String [Can be null] Change vector of the document to be patched, used to verify that the document was not changed before the patch reached it.
patch PatchRequest Patch request to be performed on the document.
patchIfMissing PatchRequest [Can be null] Patch request to be performed if no document with the given ID was found.

PatchRequest

We highly recommend using scripts with parameters. This allows RavenDB to cache scripts and boost performance. Parameters can be accessed in the script through the "args" object, and passed using PatchRequest's "Values" parameter.

Members
Script String JavaScript code to be run.
Values Map<String, Object> Parameters to be passed to the script. The parameters can be accessed using the '$' prefix. Parameter starting with a '$' will be used as is, without further concatenation .

Operations API

An operations interface that exposes the full functionality and allows performing ad-hoc patch operations without creating a session.

PatchStatus send(PatchOperation operation);

PatchStatus send(PatchOperation operation, SessionInfo sessionInfo);

<TEntity> PatchOperation.Result<TEntity> send(Class<TEntity> entityClass, PatchOperation operation);

<TEntity> PatchOperation.Result<TEntity> send(Class<TEntity> entityClass, PatchOperation operation, SessionInfo sessionInfo);

PatchOperation

Constructor
id String ID of the document to be patched.
changeVector String [Can be null] Change vector of the document to be patched, used to verify that the document was not changed before the patch reached it.
patch PatchRequest Patch request to be performed on the document.
patchIfMissing PatchRequest [Can be null] Patch request to be performed if no document with the given ID was found. Will run only if no changeVector was passed.
skipPatchIfChangeVectorMismatch boolean If false and changeVector has value, and document with that ID and change vector was not found, will throw exception.

Examples

Change Field's Value

// change firstName to Robert
session
    .advanced()
    .patch("employees/1", "FirstName", "Robert");
// change firstName to Robert
PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("this.FirstName = args.firstName");
patchRequest.setValues(Collections.singletonMap("firstName", "Robert"));
PatchCommandData patchCommandData = new PatchCommandData("employees/1", null, patchRequest, null);
session.advanced().defer(patchCommandData);

session.saveChanges();
// change firstName to Robert
PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("this.FirstName = args.firstName;");
patchRequest.setValues(Collections.singletonMap("firstName", "Robert"));
PatchOperation patchOperation = new PatchOperation("employees/1", null, patchRequest);
store.operations().send(patchOperation);

Change Values of Two Fields

// change firstName to Robert and lastName to Carter in single request
// note that in this case, we create single request, but two separate batch operations
// in order to achieve atomicity, please use the non generic APIs
session.advanced().patch("employees/1", "FirstName", "Robert");
session.advanced().patch("employees/1", "LastName", "Carter");

session.saveChanges();
// change firstName to Robert and lastName to Carter in single request
// note that here we do maintain the atomicity of the operation
PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("this.FirstName = args.firstName;" +
    "this.LastName = args.lastName");

Map<String, Object> values = new HashMap<>();
values.put("firstName", "Robert");
values.put("lastName", "Carter");
patchRequest.setValues(values);

session.advanced().defer(new PatchCommandData("employees/1", null, patchRequest, null));
session.saveChanges();
// change FirstName to Robert and LastName to Carter in single request
// note that here we do maintain the atomicity of the operation
PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("this.FirstName = args.firstName; " +
    "this.LastName = args.lastName");

Map<String, Object> values = new HashMap<>();
values.put("firstName", "Robert");
values.put("lastName", "Carter");
patchRequest.setValues(values);

store.operations().send(new PatchOperation("employees/1", null, patchRequest));

Increment Value

// increment UnitsInStock property value by 10
session.advanced().increment("products/1-A", "UnitsInStock", 10);

session.saveChanges();
PatchRequest request = new PatchRequest();
request.setScript("this.UnitsInStock += args.unitsToAdd");
request.setValues(Collections.singletonMap("unitsToAdd", 10));

session.advanced().defer(
    new PatchCommandData("products/1-A", null, request, null));
session.saveChanges();
PatchRequest request = new PatchRequest();
request.setScript("this.UnitsInStock += args.unitsToAdd");
request.setValues(Collections.singletonMap("unitsToAdd", 10));
store.operations().send(new PatchOperation("products/1-A", null, request));

Add Item to Array

BlogComment comment = new BlogComment();
comment.setContent("Lore ipsum");
comment.setTitle("Some title");

session.advanced()
    .patch("blogposts/1", "comments", comments -> comments.add(comment));

session.saveChanges();
// add a new comment to comments
BlogComment comment = new BlogComment();
comment.setContent("Lore ipsum");
comment.setTitle("Some title");

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("this.comments.push(args.comment");
patchRequest.setValues(Collections.singletonMap("comment", comment));

session.advanced().defer(new PatchCommandData("blogposts/1", null, patchRequest, null));
session.saveChanges();
// add a new comment to comments
BlogComment comment = new BlogComment();
comment.setContent("Lore ipsum");
comment.setTitle("Some title");

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("this.comments.push(args.comment");
patchRequest.setValues(Collections.singletonMap("comment", comment));

store.operations().send(new PatchOperation("blogposts/1", null, patchRequest));

Insert Item into Specific Position in Array

Inserting item into specific position is supported only by the non-typed APIs

BlogComment comment = new BlogComment();
comment.setContent("Lore ipsum");
comment.setTitle("Some title");

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("this.comments.splice(1, 0, args.comment)");
patchRequest.setValues(Collections.singletonMap("comment", comment));

session.advanced().defer(new PatchCommandData("blogposts/1", null, patchRequest, null));
session.saveChanges();
BlogComment comment = new BlogComment();
comment.setContent("Lore ipsum");
comment.setTitle("Some title");

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("this.comments.splice(1, 0, args.comment)");
patchRequest.setValues(Collections.singletonMap("comment", comment));

store.operations().send(new PatchOperation("blogposts/1", null, patchRequest));

Modify Item in Specific Position in Array

Inserting item into specific position is supported only by the non-typed APIs

// modify a comment at position 3 in Comments
BlogComment comment = new BlogComment();
comment.setContent("Lore ipsum");
comment.setTitle("Some title");

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("this.comments.splice(3, 1, args.comment)");
patchRequest.setValues(Collections.singletonMap("comment", comment));

session.advanced().defer(new PatchCommandData("blogposts/1", null, patchRequest, null));
session.saveChanges();
// modify a comment at position 3 in Comments
BlogComment comment = new BlogComment();
comment.setContent("Lore ipsum");
comment.setTitle("Some title");

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("this.comments.splice(3, 1, args.comment)");
patchRequest.setValues(Collections.singletonMap("comment", comment));

store.operations().send(new PatchOperation("blogposts/1", null, patchRequest));

Filter out Items from an Array

Filtering items from an array supported only by the non-typed APIs

//filter out all comments of a blogpost which contains the word "wrong" in their contents
PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("this.comments = this.comments.filter(comment " +
    "=> comment.content.includes(args.titleToRemove));");
patchRequest.setValues(Collections.singletonMap("titleToRemove", "wrong"));

session.advanced().defer(
    new PatchCommandData("blogposts/1", null, patchRequest, null));
session.saveChanges();
// filter out all comments of a blogpost which contains the word "wrong" in their contents
PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("this.comments = this.comments.filter(comment " +
    "=> comment.content.includes(args.titleToRemove));");
patchRequest.setValues(Collections.singletonMap("titleToRemove", "wrong"));

store.operations().send(new PatchOperation("blogposts/1", null, patchRequest));

Loading Documents in a Script

Loading documents supported only by non-typed APIs

// update product names in order, according to loaded product documents
PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("this.Lines.forEach(line => {" +
    " var productDoc = load(line.Product);" +
    " line.ProductName = productDoc.Name;" +
    "});");

session.advanced().defer(
    new PatchCommandData("orders/1", null, patchRequest, null));
session.saveChanges();
// update product names in order, according to loaded product documents
PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("this.Lines.forEach(line => {" +
    " var productDoc = load(line.Product);" +
    " line.ProductName = productDoc.Name;" +
    "});");

store.operations().send(new PatchOperation("blogposts/1", null, patchRequest));

Remove Property

Removing property supported only by the non-typed APIs

// rename firstName to First

Map<String, Object> value = new HashMap<>();
value.put("old", "FirstName");
value.put("new", "Name");

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("var firstName = this[args.rename.old];" +
    "delete this[args.rename.old];" +
    "this[args.rename.new] = firstName;");
patchRequest.setValues(Collections.singletonMap("rename", value));

session.advanced().defer(new PatchCommandData("employees/1", null, patchRequest, null));

session.saveChanges();
Map<String, Object> value = new HashMap<>();
value.put("old", "FirstName");
value.put("new", "Name");

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("var firstName = this[args.rename.old];" +
    "delete this[args.rename.old];" +
    "this[args.rename.new] = firstName;");
patchRequest.setValues(Collections.singletonMap("rename", value));

store.operations().send(new PatchOperation("employees/1", null, patchRequest));

Rename Property

Renaming property supported only by the non-typed APIs

// rename firstName to First

Map<String, Object> value = new HashMap<>();
value.put("old", "FirstName");
value.put("new", "Name");

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("var firstName = this[args.rename.old];" +
    "delete this[args.rename.old];" +
    "this[args.rename.new] = firstName;");
patchRequest.setValues(Collections.singletonMap("rename", value));

session.advanced().defer(new PatchCommandData("employees/1", null, patchRequest, null));

session.saveChanges();
Map<String, Object> value = new HashMap<>();
value.put("old", "FirstName");
value.put("new", "Name");

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("var firstName = this[args.rename.old];" +
    "delete this[args.rename.old];" +
    "this[args.rename.new] = firstName;");
patchRequest.setValues(Collections.singletonMap("rename", value));

store.operations().send(new PatchOperation("employees/1", null, patchRequest));

Add Document

Adding a new document is supported only by the non-typed APIs

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("put('orders/', { Employee: id(this) });");
PatchCommandData commandData =
    new PatchCommandData("employees/1-A", null, patchRequest, null);
session.advanced().defer(commandData);
session.saveChanges();
PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("put('orders/', { Employee: id(this) });");

store.operations().send(new PatchOperation("employees/1-A", null, patchRequest));

Clone Document

In order to clone a document use put method as follows

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("put('employees/', this);");
PatchCommandData commandData =
    new PatchCommandData("employees/1-A", null, patchRequest, null);
session.advanced().defer(commandData);
session.saveChanges();
PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("put('employees/', this);");

store.operations().send(new PatchOperation("employees/1-A", null, patchRequest));

Cloning, Attachments & Counters

The attachments and/or counters from source document will not be copied to the new one automatically.

Increment Counter

In order to increment or create a counter use incrementCounter method as follows

HashMap<String, Object> scriptValues = new HashMap<>();
scriptValues.put("name", "likes");
scriptValues.put("val", 20);

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("incrementCounter(this.Company, args.name, args.val);");
patchRequest.setValues(scriptValues);

new PatchCommandData("orders/1-A", null, patchRequest, null);
session.saveChanges();
HashMap<String, Object> scriptValues = new HashMap<>();
scriptValues.put("name", "likes");
scriptValues.put("val", -1);

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("incrementCounter(this.Company, args.name, args.val);");
patchRequest.setValues(scriptValues);

PatchOperation patchOperation = new PatchOperation("orders/1-A", null, patchRequest);
store.operations().send(patchOperation);

Method Overloading & Value restrictions

The method can be called by document ID or by document reference and the value can be negative

Delete Counter

In order to delete a counter use deleteCounter method as follows

HashMap<String, Object> scriptValues = new HashMap<>();
scriptValues.put("name", "Likes");

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("deleteCounter(this, args.name);");
patchRequest.setValues(scriptValues);

new PatchCommandData("products/1-A", null, patchRequest, null);
session.saveChanges();
HashMap<String, Object> scriptValues = new HashMap<>();
scriptValues.put("name", "Likes");

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("deleteCounter(this, args.name);");
patchRequest.setValues(scriptValues);

PatchOperation patchOperation = new PatchOperation("products/1-A", null, patchRequest);
store.operations().send(patchOperation);

Method Overloading

The method can be called by document ID or by document reference

Get Counter

In order to get a counter while patching use counter method as follows

HashMap<String, Object> scriptValues = new HashMap<>();
scriptValues.put("name", "Likes");

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("var likes = counter(this.Company, args.name);\n" +
    "put('result/', {company: this.Company, likes: likes});");
patchRequest.setValues(scriptValues);

new PatchCommandData("orders/1-A", null, patchRequest, null);
session.saveChanges();
HashMap<String, Object> scriptValues = new HashMap<>();
scriptValues.put("name", "Likes");

PatchRequest patchRequest = new PatchRequest();
patchRequest.setScript("var likes = counter(this.Company, args.name);\n" +
    "put('result/', {company: this.Company, likes: likes});");
patchRequest.setValues(scriptValues);

PatchOperation patchOperation = new PatchOperation("orders/1-A", null, patchRequest);
store.operations().send(patchOperation);

Method Overloading

The method can be called by document ID or by document reference