> For the complete documentation index, see [llms.txt](https://docs.jetadmin.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.jetadmin.io/classic-app-builder/binding-and-values.md).

# Data binding and variables

Bind Components, Extract and Pass data throughout your App

Applies to **Classic App Builder**. Screens and recordings in this section show the Classic interface.

Binding connects a source value to a component, query, page parameter, or action input.

## Understand the flow

```mermaid
flowchart LR
  A["Selected table row"] --> B["Bound field or record ID"]
  B --> C["Form, page parameter, or action input"]
  C --> D["Verify displayed value and resulting operation"]
```

Selecting a different row should update the dependent value. Passing a displayed field and passing a stable record identifier are different choices; use the value required by the target.

## Start with an example

* [Binding components](/classic-app-builder/binding-and-values/binding-components.md) explains Bind and Functions.
* [Connect a table to an edit form](/classic-app-builder/binding-and-values/binding-form-to-table.md) follows a selected record into a form.
* [Connect a filter to a table](/classic-app-builder/binding-and-values/binding-filter-to-table.md) narrows visible results.
* [Bind related tables](/classic-app-builder/binding-and-values/binding-two-related-tables.md) connects related data.
* [Extract and pass values](/classic-app-builder/binding-and-values/parameters.md) covers component and page values.
* [Variables](/classic-app-builder/binding-and-values/variables.md) stores values used by app logic.
* [Bindings across pages](/classic-app-builder/binding-and-values/binding-across-pages.md) and [across overlays](/classic-app-builder/binding-and-values/binding-across-overlays.md) cover navigation boundaries.

## Verify a binding

Check the source component, selected record, field, and value type. Test a second selection, an empty selection, and a missing value. For writes, inspect the record identifier separately from the form's editable fields.

If the value is correct but the operation fails, investigate [the action and its inputs](/classic-app-builder/actions-and-logic.md).


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