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68 lines
2.0 KiB
Markdown
68 lines
2.0 KiB
Markdown
---
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contentType: howto
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---
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# Mapping in the UI
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Data mapping means referencing data from previous nodes. It doesn't include changing (transforming) data, just referencing it.
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You can map data in the following ways:
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* Using the expressions editor.
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* By dragging and dropping data from the **INPUT** into parameters. This generates the expression for you.
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For information on errors with mapping and linking items, refer to [Item linking errors](/data/data-mapping/data-item-linking/item-linking-errors/).
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## How to drag and drop data
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1. Run your workflow to load data.
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2. Open the node where you need to map data.
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3. You can map in table, JSON, and schema view:
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* In table view: click and hold a table heading to map top level data, or a field in the table to map nested data.
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* In JSON view: click and hold a key.
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* In schema view: click and hold a key.
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4. Drag the item into the field where you want to use the data.
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### Understand what you're mapping with drag and drop
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Data mapping maps the key path, and loads the key's value into the field. For example, given the following data:
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```js
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[
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{
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"fruit": "apples",
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"color": "green"
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}
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]
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```
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You can map `fruit` by dragging and dropping **fruit** from the **INPUT** into the field where you want to use its value. This creates an expression, `{{ $json.fruit }}`. When the node iterates over input items, the value of the field becomes the value of `fruit` for each item.
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### Understand nested data
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Given the following data:
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```js
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[
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{
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"name": "First item",
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"nested": {
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"example-number-field": 1,
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"example-string-field": "apples"
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}
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},
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{
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"name": "Second item",
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"nested": {
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"example-number-field": 2,
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"example-string-field": "oranges"
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}
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}
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]
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```
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n8n displays it in table form like this:
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