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    Single Document Patch Operations

    • The Patch operation is used to perform partial document updates with one trip to the server, instead of loading, modifying, and saving 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.

    • Since the operation is executed in a single request to the database,
      the patch command is performed in a single write transaction.

    • The current page covers patch operations on single documents.

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

    • Patching can be done from the client API as well as in the studio.

    In this page:

    API Overview

    Session API

    A type-safe session interface that allows performing the most common patch operations.
    The patch request will be sent to the server only when calling SaveChanges.
    This way it's possible to perform multiple operations in one request to the server.

    Increment field value

    Session.Advanced.Increment 

    void Increment<T, U>(T entity, Expression<Func<T, U>> fieldPath, U delta);

void Increment<T, U>(string id, Expression<Func<T, U>> fieldPath, U delta);
    Parameters Type Description
    T Type Entity type
    U Type Field type, 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.
    fieldPath Expression<Func<T, U>> Lambda describing the path to the field.
    delta U Value to be added.

    Session.Advanced.AddOrIncrement 

    void AddOrIncrement<T, TU>(string id, T entity, Expression<Func<T, TU>> path, TU valToAdd);
    Parameters Type Description
    T Type Entity type
    TU Type Field type, 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.
    path Expression<Func<T, TU>> Lambda describing the path to the field.
    valToAdd U Value to be added.

    Set field value

    Session.Advanced.Patch 

    void Patch<T, U>(string id, Expression<Func<T, U>> fieldPath, U value);

void Patch<T, U>(T entity, Expression<Func<T, U>> fieldPath, U value);
    Parameters Type Description
    T Type Entity type
    U Type Field type
    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.
    fieldPath Expression<Func<T, U>> Lambda describing the path to the field.
    delta U Value to set.

    Session.Advanced.AddOrPatch

    void AddOrPatch<T, TU>(string id, T entity, Expression<Func<T, TU>> path, TU value);
    Parameters Type Description
    T Type Entity type
    TU Type Field type
    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.
    fieldPath Expression<Func<T, TU>> Lambda describing the path to the field.
    value U Value to set.

    Array manipulation

    Session.Advanced.Patch 

    void Patch<T, U>(T entity, Expression<Func<T, IEnumerable<U>>> fieldPath,
    Expression<Func<JavaScriptArray<U>, object>> arrayModificationLambda);

void Patch<T, U>(string id, Expression<Func<T, IEnumerable<U>>> fieldPath,
    Expression<Func<JavaScriptArray<U>, object>> arrayModificationLambda);
    Parameters Type Description
    T Type Entity type
    U Type Field type
    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.
    fieldPath Expression<Func<T, U>> Lambda describing the path to the field.
    arrayModificationLambda Expression<Func<JavaScriptArray<U>, object>> Lambda that modifies the array, see JavaScriptArray below.

    Session.Advanced.AddOrPatch 

    void AddOrPatch<T, TU>(string id, T entity, Expression<Func<T, List<TU>>> path, 
    Expression<Func<JavaScriptArray<TU>, object>> arrayAdder);
    Parameters Type Description
    T Type Entity type
    TU Type Field type
    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.
    path Expression<Func<T, TU>> Lambda describing the path to the field.
    Expression<Func Expression<Func<JavaScriptArray<TU>, object>> Lambda that modifies the array, see JavaScriptArray below.
    arrayAdder Add() Values to add to array.

    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(params T[] items) JavaScriptArray Items to be added to the array.
    RemoveAt(int index) JavaScriptArray Removes item in position index in array.
    RemoveAll(Func<T, bool> predicate) JavaScriptArray Removes all the items in the array that satisfy the given predicate.

    Session API using Defer

    The non-typed Session API for patches uses the Session.Advanced.Defer function which allows registering one or more commands.
    One of the possible commands is the PatchCommandData, describing single document patch command.
    The patch request will be sent to the server only when calling 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 Type Description
    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.

    Property Type Description
    Script string The patching script, written in JavaScript.
    Values Dictionary<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.

    Raven.Client.Documents.Operations.Send
    Raven.Client.Documents.Operations.SendAsync 

    PatchStatus Send(PatchOperation operation);

Task<PatchStatus> SendAsync(PatchOperation operation, 
                            SessionInfo sessionInfo = null, 
                            CancellationToken token = default(CancellationToken));

    PatchOperation

    Constructor Type Description
    id string ID of the document to be patched.
    changeVector string Change vector of the document to be patched.
    Used to verify that the document was not modified before the patch reached it.
    Can be null.
    patch PatchRequest Patch request to perform on the document.
    patchIfMissing PatchRequest Patch request to perform if the specified document is not found.
    Will run only if no changeVector was passed.
    Can be null.
    skipPatchIfChangeVectorMismatch bool true - do not patch if the document has been modified.
    false (Default) - execute the patch even if document has been modified.

    An exception is thrown if:
    this param is false + changeVector has value + document with that ID and change vector was not found.

    List of script methods

    This is a list of a few of the javascript methods that can be used in patch scripts.
    See the more comprehensive list at Knowledge Base: JavaScript Engine.

    Method Arguments Description
    load string or string[] Loads one or more documents into the context of the script by their document IDs
    loadPath A document and a path to an ID within that document Loads a related document by the path to its ID
    del Document ID; change vector Delete the given document by its ID. If you add the expected change vector and the document's current change vector does not match, the document will not be deleted.
    put Document ID; document; change vector Create or overwrite a document with a specified ID and entity. If you try to overwrite an existing document and pass the expected change vector, the put will fail if the specified change vector does not match the document's current change vector.
    cmpxchg Key Load a compare exchange value into the context of the script using its key
    getMetadata Document Returns the document's metadata
    id Document Returns the document's ID
    lastModified Document Returns the DateTime of the most recent modification made to the given document
    counter Document; counter name Returns the value of the specified counter in the specified document
    counterRaw Document; counter name Returns the specified counter in the specified document as a key-value pair
    incrementCounter Document; counter name Increases the value of the counter by one
    deleteCounter Document; counter name Deletes the counter
    spatial.distance Two points by latitude and longitude; spatial units Find the distance between to points on the earth
    timeseries Document; the time series' name Returns the specified time series object

    Examples

    Change value of single field

    // change FirstName to Robert                
session.Advanced.Patch<Employee, string>(
    "employees/1",
    x => x.FirstName, "Robert");

session.SaveChanges();
    // change FirstName to Robert                
session.Advanced.Defer(new PatchCommandData(
    id: "employees/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = @"this.FirstName = args.FirstName;",
        Values =
        {
            {"FirstName", "Robert"}
        }
    },
    patchIfMissing: null));

session.SaveChanges();
    // change FirstName to Robert                
store.Operations.Send(new PatchOperation(
    id: "employees/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = @"this.FirstName = args.FirstName;",
        Values =
        {
            {"FirstName", "Robert"}
        }
    },
    patchIfMissing: null));

    Change values of two fields

    // Modify FirstName to Robert and LastName to Carter in single request
// ===================================================================

// The two Patch operations below are sent via 'SaveChanges()' which complete transactionally,
// as this call generates a single HTTP request to the database.
// Either both will succeed or both will be rolled back since they are applied within the same transaction.
// However, on the server side, the two Patch operations are still executed separately.
// To achieve atomicity at the level of a single server-side operation, use 'Defer' or the operations syntax.

session.Advanced.Patch<Employee, string>("employees/1", x => x.FirstName, "Robert");
session.Advanced.Patch<Employee, string>("employees/1", x => x.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
session.Advanced.Defer(new PatchCommandData(
    id: "employees/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = @"
                this.FirstName = args.UserName.FirstName;
                this.LastName = args.UserName.LastName;",
        Values =
        {
            {
                "UserName", new
                {
                    FirstName = "Robert",
                    LastName = "Carter"
                }
            }
        }
    },
    patchIfMissing: 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
store.Operations.Send(new PatchOperation(
    id: "employees/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = @"
                this.FirstName = args.UserName.FirstName;
                this.LastName = args.UserName.LastName;",
        Values =
        {
            {
                "UserName", new
                {
                    FirstName = "Robert",
                    LastName = "Carter"
                }
            }
        }
    }, patchIfMissing: null));

    Increment value

    // increment UnitsInStock property value by 10
session.Advanced.Increment<Product, int>("products/1-A", x => x.UnitsInStock, 10);

session.SaveChanges();
    session.Advanced.Defer(new PatchCommandData(
    id: "products/1-A",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = @"this.UnitsInStock += args.UnitsToAdd;",
        Values =
        {
            {"UnitsToAdd", 10}
        }
    },
    patchIfMissing: null));

session.SaveChanges();
    store.Operations.Send(new PatchOperation(
    id: "products/1-A",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = @"this.UnitsInStock += args.UnitsToAdd;",
        Values =
        {
            {"UnitsToAdd", 10}
        }
    },
    patchIfMissing: null));

    Add or increment

    AddOrIncrement increments an existing field or adds a new one in documents where they didn't exist.

    // While running AddOrIncrement specify <entity type, field type>
session.Advanced.AddOrIncrement<User, int>(

        // Specify document id and entity on which the operation should be performed.
        id,
        new User
        {
            FirstName = "John",
            LastName = "Doe",
            LoginCount = 1

        // The path to the field and value to be added.
        }, x => x.LoginCount, 1);

    session.SaveChanges();

    Add or patch

    AddOrPatch adds or edits field(s) in a single document.

    If the document doesn't yet exist, this operation adds the document but doesn't patch it. 

    // While running AddOrPatch specify <entity type, field type>
session.Advanced.AddOrPatch<User, DateTime>(

// Specify document id and entity on which the operation should be performed.
    id,
    new User
    {
        FirstName = "John",
        LastName = "Doe",
        LastLogin = DateTime.Now
    },
    // The path to the field and value to set.
    x => x.LastLogin, new DateTime(2021, 9, 12));

session.SaveChanges();

    Add or patch to an existing array

    This sample shows how to patch an existing array or add it to documents where it doesn't yet exist.

    // While running AddOrPatch specify <entity type, field type>
session.Advanced.AddOrPatch<User, DateTime>(

    // Specify document id and entity on which the operation should be performed.
    id,
    new User
    {
        FirstName = "John",
        LastName = "Doe",
        LoginTimes =
        new List<DateTime>
        {
                DateTime.UtcNow
        }
    },
    // The path to the field
    x => x.LoginTimes,
    // Modifies the array
    u => u.Add(new DateTime(1993, 09, 12), new DateTime(2000, 01, 01)));

session.SaveChanges();

    Add item to array

    // add a new comment to Comments
session.Advanced.Patch<BlogPost, BlogComment>("blogposts/1",
    x => x.Comments,
    comments => comments.Add(new BlogComment
    {
        Content = "Lore ipsum",
        Title = "Some title"
    }));

session.SaveChanges();
    // add a new comment to Comments
session.Advanced.Defer(new PatchCommandData(
    id: "blogposts/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = "this.Comments.push(args.Comment);",
        Values =
        {
            {
                "Comment", new BlogComment
                {
                    Content = "Lore ipsum",
                    Title = "Some title"
                }
            }
        }

    },
    patchIfMissing: null));

session.SaveChanges();
    // add a new comment to Comments
store.Operations.Send(new PatchOperation(
    id: "blogposts/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = "this.Comments.push(args.Comment);",
        Values =
        {
            {
                "Comment", new BlogComment
                {
                    Content = "Lore ipsum",
                    Title = "Some title"
                }
            }
        }

    },
    patchIfMissing: null));

    Insert item into specific position in array

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

    // insert a new comment at position 1 to Comments
session.Advanced.Defer(new PatchCommandData(
    id: "blogposts/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = "this.Comments.splice(1, 0, args.Comment);",
        Values =
        {
            {
                "Comment", new BlogComment
                {
                    Content = "Lore ipsum",
                    Title = "Some title"
                }
            }
        }
    },
    patchIfMissing: null));

session.SaveChanges();
    store.Operations.Send(new PatchOperation(
    id: "blogposts/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = "this.Comments.splice(1, 0, args.Comment);",
        Values =
        {
            {
                "Comment", new BlogComment
                {
                    Content = "Lore ipsum",
                    Title = "Some title"
                }
            }
        }
    },
    patchIfMissing: null));

    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
session.Advanced.Defer(new PatchCommandData(
    id: "blogposts/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = "this.Comments.splice(3, 1, args.Comment);",
        Values =
        {
            {
                "Comment", new BlogComment
                {
                    Content = "Lore ipsum",
                    Title = "Some title"
                }
            }
        }
    },
    patchIfMissing: null));

session.SaveChanges();
    // modify a comment at position 3 in Comments
store.Operations.Send(new PatchOperation(
    id: "blogposts/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = "this.Comments.splice(3, 1, args.Comment);",
        Values =
        {
            {
                "Comment", new BlogComment
                {
                    Content = "Lore ipsum",
                    Title = "Some title"
                }
            }
        }
    },
    patchIfMissing: null));

    Remove items from array

    // filter out all comments of a blogpost which contains the word "wrong" in their contents 
session.Advanced.Patch<BlogPost, BlogComment>("blogposts/1",
    x => x.Comments,
    comments => comments.RemoveAll(y => y.Content.Contains("wrong")));

session.SaveChanges();
    // filter out all comments of a blogpost which contains the word "wrong" in their contents 
session.Advanced.Defer(new PatchCommandData(
    id: "blogposts/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = @"this.Comments = this.Comments.filter(comment=>
                 !comment.Content.includes(args.Text));",
        Values =
        {
            {"Text", "wrong"}
        }
    },
    patchIfMissing: null));

session.SaveChanges();
    // filter out all comments of a blogpost which contains the word "wrong" in their contents
store.Operations.Send(new PatchOperation(
    id: "blogposts/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = @"this.Comments = this.Comments.filter(comment=>
                 !comment.Content.includes(args.Text));",
        Values =
        {
            {"Text", "wrong"}
        }
    },
    patchIfMissing: null));

    Loading documents in a script

    Loading documents is supported only by the non-typed APIs.

    // update product names in order, according to loaded product documents
session.Advanced.Defer(new PatchCommandData(
    id: "orders/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = @"this.Lines.forEach(line=> { 
                var productDoc = load(line.Product);
                line.ProductName = productDoc.Name;
                });"
    }, patchIfMissing: null));

session.SaveChanges();
    // update product names in order, according to loaded product documents
store.Operations.Send(new PatchOperation(
    id: "blogposts/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = @"this.Lines.forEach(line=> { 
                var productDoc = load(line.Product);
                line.ProductName = productDoc.Name;
                });"
    },
    patchIfMissing: null));

    Remove property

    Removing property supported only by the non-typed APIs.

    // remove property Age
session.Advanced.Defer(new PatchCommandData(
    id: "employees/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = @"delete this.Age;"
    },
    patchIfMissing: null));
session.SaveChanges();
    // remove property Age
store.Operations.Send(new PatchOperation(
    id: "employees/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = @"delete this.Age;"
    },
    patchIfMissing: null));

    Rename property

    Renaming property supported only by the non-typed APIs.

    // rename FirstName to Name
session.Advanced.Defer(new PatchCommandData(
    id: "employees/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = @"var firstName = this[args.Rename.Old];
                delete this[args.Rename.Old];
                this[args.Rename.New] = firstName;",
        Values =
        {
            {
                "Rename", new
                {
                    Old = "FirstName",
                    New = "Name"
                }
            }
        }
    },
    patchIfMissing: null));

session.SaveChanges();
    store.Operations.Send(new PatchOperation(
    id: "employees/1",
    changeVector: null,
    patch: new PatchRequest
    {
        Script = @"var firstName = this[args.Rename.Old];
                delete this[args.Rename.Old];
                this[args.Rename.New] = firstName;",
        Values =
        {
            {
                "Rename", new
                {
                    Old = "FirstName",
                    New = "Name"
                }
            }
        }
    },
    patchIfMissing: null));

    Add document

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

    session.Advanced.Defer(new PatchCommandData("employees/1-A", null,
    new PatchRequest
    {
        Script = "put('orders/', { Employee: id(this) });",
    }, null));

session.SaveChanges();
    store.Operations.Send(new PatchOperation("employees/1-A", null, new PatchRequest
{
    Script = "put('orders/', { Employee: id(this) });",
}));

    Clone document

    In order to clone a document use put method as follows.

    session.Advanced.Defer(new PatchCommandData("employees/1-A", null,
    new PatchRequest
    {
        Script = "put('employees/', this);",
    }, null));

session.SaveChanges();
    store.Operations.Send(new PatchOperation("employees/1-A", null, new PatchRequest
{
    Script = "put('employees/', this);",
}));

    Attachments, Counters, Time Series, and Revisions:

    Attachments, counters, time series data, and revisions from the source document will Not be copied
    to the new document automatically.

    Increment counter

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

    var order = session.Load<Order>("orders/1-A");
session.CountersFor(order).Increment("Likes", 1);
session.SaveChanges();
    session.Advanced.Defer(new PatchCommandData("orders/1-A", null,
    new PatchRequest
    {
        Script = "incrementCounter(this, args.name, args.val);",
        Values =
        {
            { "name", "Likes" },
            { "val", 20 }
        }
    }, null));
session.SaveChanges();
    store.Operations.Send(new PatchOperation("orders/1-A", null, new PatchRequest
{
    Script = "incrementCounter(this, args.name, args.val);",
    Values =
    {
        { "name", "Likes" },
        { "val", -1 }
    }
}));

    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:

    session.CountersFor("orders/1-A").Delete("Likes");
session.SaveChanges();
    session.Advanced.Defer(new PatchCommandData("products/1-A", null,
    new PatchRequest
    {
        Script = "deleteCounter(this, args.name);",
        Values =
        {
            { "name", "Likes" },
        }
    }, null));
session.SaveChanges();
    store.Operations.Send(new PatchOperation("products/1-A", null, new PatchRequest
{
    Script = "deleteCounter(this, args.name);",
    Values =
    {
        { "name", "Likes" },
    }
}));

    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:

    var order = session.Load<Order>("orders/1-A");
var counters = session.Advanced.GetCountersFor(order);
    session.Advanced.Defer(new PatchCommandData("orders/1-A", null,
    new PatchRequest
    {
        Script = @"var likes = counter(this.Company, args.name);
                   put('result/', {company: this.Company, likes: likes});",
        Values =
        {
            { "name", "Likes" },
        }
    }, null));
session.SaveChanges();
    store.Operations.Send(new PatchOperation("orders/1-A", null, new PatchRequest
{
    Script = @"var likes = counter(this.Company, args.name);
               put('result/', {company: this.Company, likes: likes});",
    Values =
    {
        { "name", "Likes" },
    }
}));

    Method overloading

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

    related articlesRelated Articles

    Patching

    Knowledge Base

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