# Changed Elements

The Changed Elements API provides consumers with the elements that have changed in an iModel between two changesets. This API has two operations:

1. Enable Change Tracking
2. Get Comparison

Before obtaining a comparison, it is necessary to enable change tracking of an iModel. This means that the API will be listening to any new `Named Versions` that are created on the iModel. When that happens, the API will process the new changes and store a summary of all the elements that have changed.

After tracking is enabled and the iModel is processed, the comparison endpoint may be used to query for a summary of changed elements between any two given `ChangeSets`.

changed-elements

Project Delivery

---

Enables or disables change tracking for an iModel. This operation requires you to pass the enable value, iModel Id and project Id in the body of the request as a JSON object.

Once enabled, whenever a new named version is created in the iModel, the changesets will be processed to find all changed elements. This data can then be requested by using the Get Comparison operation.

### Authentication

Requires `Authorization` header with valid Bearer token for scope `changedelements:modify`.

For more documentation on authorization and how to get access token visit [OAUTH2 Authorization](https://developer.bentley.com/apis/overview/authorization/) page.

---

enable-change-tracking

The body should contain a JSON object with the enable value, iModel Id and project Id.

OAuth access token with scope `changedelements:modify`

Authorization

Setting to `application/vnd.bentley.itwin-platform.v1+json` is recommended.

Accept

Change tracking for iModel was updated successfully.

This response indicates that request lacks valid authentication credentials. Access token might not been provided, issued by the wrong issuer, does not have required scopes or request headers were malformed.

The user has insufficient permissions for the requested operation.

This response indicates that disabling change tracking is not possible because the iModel is not valid.

A URL parameter was malformed or the body of the request is invalid.

application/json;InvalidChangedElementsRequest

This response indicates that the user has sent too many requests in a given amount of time.

The number of requests exceeds the rate-limit for the client subscription.

retry-after

---

Obtains which elements have changed in the iModel between the given start and end changesets.

This information will only be available after change tracking has been enabled and the processing operation completes.

### Authentication

Requires `Authorization` header with valid Bearer token for scope `changedelements:read`.

For more documentation on authorization and how to get access token visit [OAUTH2 Authorization](https://developer.bentley.com/apis/overview/authorization/) page.

---

get-comparison

iModelId

projectId

startChangesetId

endChangesetId

OAuth access token with scope `changedelements:read`

This response indicates that provided comparison results are not ready or unexistent.

A URL parameter was malformed or there are missing required parameters.

Compare ChangedElements between Version and colorizing them by operation.

ecc2e721-1760-47b7-b3db-4647a84c2cfa

Uses the validation REST api to get and visualize clash results.

dc1910b2-a6dc-4848-81c1-df4e9d20ccdd

Uses issues REST API to retrieve issues associated with project and display them.

d7203008-19a4-4c45-8c64-3f16cc8b396a

Request and visualize the data in an insights report of iModel

6f6ed2b0-54b1-4645-8154-7c1b2c4eed21

How use the Transformations API to transform an iModel into another, and display them.

2f29a62e-2085-4c2b-a3e6-e85a444fbfaf

0c0e4c99-b759-4eda-b8c1-a96b9f66c1ef

This is a code sample application that demonstrates usage of the Synchronization API on the Bentley iTwin developer platform.

synchronization-api-sample-app

This is a code sample application that demonstrates usage of the Synchronization Manifest API on the Bentley iTwin developer platform.

synchronization-manifest-api-sample

This is a simple React based application that demonstrates iModel management workflow that can be achieved using iModels API.

imodels-api-management-workflow-sample-app

An iTwin sample application that demonstrates how to create, query and update files with folders saved in the Storage.

storage-api-sample-app

An iTwin sample application that demonstrates how to create, query and update an iTwin Project using the Project API. It also demonstrates how to create a project role and add a user to the project with that role.

project-api-sample-app

Node.js (Express) application that can capture webhook events, store the events in Azure Queue and provide an API endpoint for event polling.

webhooks-api-polling-sample-app

Node.js (Express) application that shows the basic examples of consuming Webhooks API and reacting to iTwin Platform events.

webhooks-api-sample-app

This sample demonstrates importing users into a project along with a list of project role assignments per user and copying project roles, users, and user project role assignments from one project to another.

platform-api-samples

This is a simple command line app that illustrates the workflow of configuring a report using the Reporting platform APIs.

insights-api-sample-console-app

The Design Element Classification sample is a simple command line app that illustrates the workflow of checking available model versions deployed and running a new run for an iModel.

designelementclassification-api-sample-console-app

An iTwin sample application that demonstrates how to create, upload and query components in a catalog.

library-api-sample-app

An iTwin.js  application that lets you view 2D models

88182d1b-b11f-457e-bcb1-7e5c449a341c

This is the simplest iTwin.js frontend example. It displays a viewport and shows a view navigation toolbar

483a9a98-d509-44ed-9699-a5bc8e7085a8

This sandbox demonstrates the display of global data sources and globe-based navigation terrain buildings global location maps

cc24218c-042a-4a96-b54a-f25beb570965

Adding, removing, and modifying the display of reality data. Discovers available realitymodel and attaches the first one to the viewport.

acf25c84-0665-459d-8b2b-f025566c379a

How to get and set various ViewFlags and other view attributes including: RenderMode, Skybox, BackgroundMap, Grid, ACS, and others.

83bafc4a-f9e4-406d-934b-b3c69bde1614

Animates the camera along a path using setEyePoint.  Also shows a tool to control the look direction using setupViewFromFrustum.

12510a7a-3103-4795-addc-4026cabeda2e

How to apply a classifier to a realitymodel. Also demonstrates how to adjust the display of classifier, in this case a spatial classifier

026f60e8-1e30-466e-8c90-c2feb6f0ace4

This sample demonstrates how to implement basic cross-probing between 2D and 3D elements given an iModel of a Plant

18f5a227-1aa2-4f2f-b692-4d269cc56400

Customize the appearance of a 3d viewport using Display Styles

593d8ba7-550c-4176-af17-7d0def871da8

How to emphasize, hide, isolate, and override the color of elements using the EmphasizeElements API.

5180d906-3629-476b-90bc-d7e0d04e0dc9

Uses a TileTree to create an explode effect in the viewport.

68f4318f-5ecf-4290-b225-9114304e77cf

Creates an fire effect using particles Decorator.

7a9669c3-bda7-456b-9a92-454f561c15b2

Uses a Decorator to show a heatmap as a WorldOverlay on top of the viewport.

eca24a40-0aef-4ae1-aa10-48942204350a

Navigate between 2d and 3d views using hyper-modeling

cd20e590-d269-4f41-88e2-61551e3000ed

Exports visible viewport of iModel as PNG image. ImageExport

a2d84a9e-bdc2-4aea-848f-7f244f360278

How to simulate out-of-bound condition from a sensor and trigger IotAlert, blinking effect

0d1a3def-21a0-4f6f-b460-79193fc072c7

Uses a Decorator and a MarkerSet to display markers that indicate important locations in a model.

cfb50148-c585-4ea4-83c3-b171b6e640ec

Demonstrates displaying two viewports showing the same 3d model

8a4d5108-1f1c-472e-9749-ed15c7f90454

Uses the Presentation API to display element properties.

bebdf96d-d17b-4df5-b6cb-1ea95de15206

Shows scientific visualization and animation

dbc77226-ed66-4f8d-9d41-ae4586811c05

Demonstrates how to create and apply screen-space effects to a viewport

a6ddfa10-0844-439a-8680-c94cbc2da46c

How to serialize, deserialize and load a viewstate from JSON.

7f343b1f-11e9-435d-b246-f4a9acbb6e03

Shows how to adjust the solar lighting by using setSunTime

2a07a523-873b-4f18-ab6a-fa96b005d5b3

Creates a snow overlay using particles Decorator.

44c5d17a-396f-44aa-900e-a1eafae34410

Compare models and reality data using a clip and a TileGraphicsProvider in a single viewport.

1fd4dd9d-7834-4782-a112-99bcd1e45061

Renders using thematic display by changing the styles.

5213cb53-4226-4d1a-aeda-839f42f12144

Shows customized element tooltips by supplying a ToolAdmin that overrides the getToolTip method.

cf8bcd92-dbe1-487c-9237-e53ee6d57cc6

How to add a ClipVolume, ClipPlane, and ViewClipDecorationProvider to a view to clip the geometry

31db97c1-19fa-4ade-aa32-3d0db7b88d41

Query SpatialElements using SpatialQueries. Elements are classified using getGeometryContainment. To color and represent elements EmphasizeElements and PresentationLabelsProvider are being used.

0885edb9-08ea-42e6-b5bf-edf91e7eb90e

Uses zoomToElement, ZoomToOptions, and ViewChangeOptions to center the view on element(s) of interest.

17ad88be-df3b-4d3d-a15d-a672b684cfc2

6fd6473e-532c-4188-a149-8b76221de11c

Demonstrates how to use the Frontstage API

b3dc588c-5621-400c-a966-2f7367412a42

Geometry sample showing how to generate, translate, and rotate different types of 2d geometry.

cfe1e2cd-4f5c-4faa-8df5-0c4f5078da6c

Geometry sample showing how to generate several 3d pieces of geometry including mitered pipes, rotational, linear, and ruled, sweeps.

2943f6f9-3c37-418f-bf2c-2f15ee5b082b

Geometry sample showing how to find the closest point on a curve by using the closestPoint method.

8c33d7cd-8bd6-49e0-b75a-793f29691b06

Geometry sample showing how to find a point along a set fraction of a curve using the fractionToPointAndDerivative method

a67bf9ae-e69e-49d9-84e7-dd9b3fb39f49

Geometry sample showing how to generate simple types of 3d geometry.

1b1f5d82-ea5e-4328-8ba8-4d4860fcb853

Geometry sample showing how to create animation using multiple 2d shapes.

fc62d232-3153-417d-b023-4598b653f6f3

Simple geometry sample showing how to create a line segment using LineSegment3d and create points along it using fractionToPoint.

94dbf42e-dd29-47fc-8156-0e29fe0f15aa

Component sample showing different styles of badges.

c1037936-63fd-4519-afe6-a0bfe1cd60a1

Component sample showing different styles of buttons.

c2025f82-8bde-449d-84d0-dc4c3476d48f

Component sample showing different styles of checklistboxes.

8b122039-b552-4ed1-b133-64bf1056d32f

Component sample showing different styles of expandable lists.

5d10bfa7-14c6-428e-8e64-3650093ca41c

Component sample showing different styles of inputs.

9d75ee2c-090f-4b05-9045-97492653c086

Component sample showing different styles of loading icons.

29789acf-3ba4-4954-82a2-5d0dba7eb2d8

Component sample showing different styles of search boxes.

7e9541c2-02cd-4945-9708-ca93eec0389e

Component sample showing different styles of sliders.

ea41e4a0-4937-4a34-890c-5b2115d795c9

Component sample showing different styles of tabs.

c2d1247e-ec37-4e07-87bc-b8e0e9063f58

Component sample showing different styles of text.

f96c2ca4-b899-427d-b5ab-4d47d26076d0

Component sample showing different styles of tiles.

14f25f71-c272-48f5-8cd9-2dd0070e2a86

Component sample showing different styles of toggles.

43c5d122-5d50-43b7-9bc5-502db6ea016b

Tree sample showing how to create a simple tree using a ControlledTree component.

c8315ba1-d509-4a2a-a1c7-369ae266d3a1

Tree sample showing how to create a tree with custom checkboxes using a ImageCheckBox component.

9599ba11-3745-4dac-89c9-b12eeaaa2abc

Tree sample showing how to create a tree with custom events using a TreeEventHandler.

ca1c2147-7b14-4f10-84c1-aebd333f962f

Tree sample showing how to create two different trees, one that loads data from memory, and the other using presentation rules.

3dd5e479-81b0-4e4b-9325-4bdbcb81c150

Tree sample showing how to override the default node rendering of a tree.

921e5c21-56b0-4f2f-bbea-6951d7e8c18e

Tree sample showing how to display custom icons using iModel data.

9c453b46-8bfd-4f9a-85dc-fb86f2399c1e

b0a3e4ec-300c-4a9e-887a-765d598864c5

Tree sample showing how to use events that interact with a viewport using useUnifiedSelectionTreeEventHandler.

Changed Elements

Samples