> ## Documentation Index
> Fetch the complete documentation index at: https://docs.pixeltable.com/llms.txt
> Use this file to discover all available pages before exploring further.

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# json

> <a href="https://github.com/pixeltable/pixeltable/blob/main/pixeltable/functions/json.py#L0" id="viewSource" target="_blank" rel="noopener noreferrer"><img src="https://img.shields.io/badge/View%20Source%20on%20Github-blue?logo=github&labelColor=gray" alt="View Source on GitHub" style={{ display: 'inline', margin: '0px' }} noZoom /></a>

# <span style={{ 'color': 'gray' }}>module</span>  pixeltable.functions.json

Pixeltable UDFs for `JsonType`.

Example:

```python  theme={null}
import pixeltable as pxt
import pixeltable.functions as pxtf

t = pxt.get_table(...)
t.select(pxtf.json.make_list(t.json_col)).collect()
```

## <span style={{ 'color': 'gray' }}>iterator</span>  list\_iterator()

```python Signature theme={null}
@pxt.iterator
list_iterator(elements: pxt.Json[(Json = None, *, mode: pxt.String = 'strict', **kwargs)
```

Iterator over elements of a list or lists. There are two distinct call patterns: either a single positional
argument; or one or more keyword arguments.

* If a single positional argument is specified, as in `list_iterator(t.col)`, then the elements of `t.col` must
  contain lists of dictionaries with matching signatures (identical keys and compatible value types). The
  iterator will yield one new column for each key in the dictionaries, and one output row per element in the
  lists.
* If multiple keyword arguments are specified, as in `list_iterator(val_1=t.col_1, val_2=t.col_2)`, then the
  elements of each input column must contain lists, but not necessarily lists of dictionaries. The iterator
  will yield one new column for each keyword argument, zipping together the individual lists.

All of the inputs must be *typed* `Json` expressions. Untyped Json will be rejected (the type schema is
necessary in order for Pixeltable to determine the types of the output columns).

**Parameters:**

* **`elements`** (`pxt.Json[(Json`): A list of dictionaries to iterate over. The dictionary keys will be used as column names in the
  output. Cannot be specified together with keyword arguments.
* **`mode`** (`Any`): Only applies when called with keyword arguments. Determines how to handle lists of different lengths:
  * `'strict'`: Raises an error if the input lists have different lengths.
  * `'truncated'`: Iterates until the shortest input list is exhausted, ignoring any remaining elements in
    longer lists.
  * `'padded'`: Iterates until the longest input list is exhausted, yielding `None` for any missing
    elements from shorter lists.
* **`**kwargs`** (`Any`): One or more lists to iterate over. The kwarg names will be used as column names in the output.
  Cannot be specified together with `elements`.

## <span style={{ 'color': 'gray' }}>udf</span>  dumps()

```python Signature theme={null}
@pxt.udf
dumps(obj: pxt.Json) -> pxt.String
```

Serialize a JSON object to a string.

Equivalent to [`json.dumps()`](https://docs.python.org/3/library/json.html#json.dumps).

**Parameters:**

* **`obj`** (`pxt.Json`): A JSON-serializable object (dict, list, or scalar).

**Returns:**

* `pxt.String`: A JSON-formatted string.

## <span style={{ 'color': 'gray' }}>udf</span>  make\_list()

```python Signature theme={null}
@pxt.udf
make_list(*args, **kwargs) -> pxt.Json[(Json, ...)]
```

Collects arguments into a list.


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