- Kibana Guide: other versions:
- What is Kibana?
- What’s new in 8.3
- Kibana concepts
- Quick start
- Set up
- Install Kibana
- Configure Kibana
- Alerting and action settings
- APM settings
- Banners settings
- Enterprise Search settings
- Fleet settings
- i18n settings
- Logging settings
- Logs settings
- Metrics settings
- Monitoring settings
- Reporting settings
- Search sessions settings
- Secure settings
- Security settings
- Spaces settings
- Task Manager settings
- Telemetry settings
- URL drilldown settings
- Start and stop Kibana
- Access Kibana
- Securing access to Kibana
- Add data
- Upgrade Kibana
- Configure security
- Configure reporting
- Configure logging
- Configure monitoring
- Command line tools
- Production considerations
- Discover
- Dashboard and visualizations
- Canvas
- Maps
- Build a map to compare metrics by country or region
- Track, visualize, and alert on assets in real time
- Map custom regions with reverse geocoding
- Heat map layer
- Tile layer
- Vector layer
- Plot big data
- Search geographic data
- Configure map settings
- Connect to Elastic Maps Service
- Import geospatial data
- Troubleshoot
- Reporting and sharing
- Machine learning
- Graph
- Alerting
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- Stack Management
- REST API
- Get features API
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- User session management APIs
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- Data views API
- Index patterns APIs
- Alerting APIs
- Action and connector APIs
- Cases APIs
- Import and export dashboard APIs
- Logstash configuration management APIs
- Machine learning APIs
- Short URLs APIs
- Get Task Manager health
- Upgrade assistant APIs
- Kibana plugins
- Troubleshooting
- Accessibility
- Release notes
- Developer guide
Fetch and manipulate data
editFetch and manipulate data
editSo far, you have only seen expressions as a way to produce visualizations, but that’s not really what’s happening. Expressions only produce data, which is then used to create something, which in the case of Canvas, means rendering an element. An element can be a visualization, driven by data, but it can also be something much simpler, like a static image. Either way, an expression is used to produce an output that is used to render the desired result. For example, here’s an expression that shows an image:
image dataurl=https://placekitten.com/160/160 mode="cover"
But as mentioned, this doesn’t actually render that image, but instead it produces some output that can be used to render that image. That’s an important distinction, and you can see the actual output by adding in the render function and telling it to produce debug output. For example:
image dataurl=https://placekitten.com/160/160 mode="cover" | render as=debug
The follow appears as JSON output:
{ "type": "image", "mode": "cover", "dataurl": "https://placekitten.com/160/160" }
You may need to expand the element’s size to see the whole output.
Canvas uses this output’s data type to map to a specific renderer and passes the entire output into it. It’s up to the image render function to produce an image on the workpad’s page. In this case, the expression produces some JSON output, but expressions can also produce other, simpler data, like a string or a number. Typically, useful results use JSON.
Canvas uses the output to render an element, but other applications can use expressions to do pretty much anything. As stated previously, expressions simply execute functions, and the functions are all written in Javascript. That means if you can do something in Javascript, you can do it with an expression.
This can include:
- Sending emails
- Sending notifications
- Reading from a file
- Writing to a file
- Controlling devices with WebUSB or Web Bluetooth
- Consuming external APIs
If your Javascript works in the environment where the code will run, such as in Node.js or in a browser, you can do it with an expression.