# Hierarchical JSON Input

You can use the Hierarchical JSON input step to load JSON data into PDI from a file. You can use filters to load only the desired data. The data can be split on a hierarchical data path using wildcards.

You can specify the input file directly in this step or use a list of files from an input field. For an overview of hierarchical data in Pentaho, see [Hierarchical data](/pdia-data-integration/extracting-data-into-pdi/hierarchical-data.md).

You can use filters on the input even if you do not use **Split rows across path**, but the filters must be set to the root level of the HDT you want to load.

When you use **Split rows across path**, you must specify all filter paths rooted at the split path. If you do not use **Split rows across path**, a normal HDT extraction path is used. See the [Hierarchical data path specifications](broken://spaces/YwnJ6Fexn4LZwKRHghPK/pages/ji5ygWJ7r8yORvFw3Rjj).

### Step name

* **Step name**: Specifies the unique name of the Hierarchical JSON input step on the canvas. You can customize the name or leave it as the default.

### Options

The Hierarchical JSON input step features the following tabs.

#### Source tab

![Hierarchical JSON Input step dialog box showing source tab](/files/0uiDcFrVyIJFcJyeELrF)

| Option/Field             | Description                                                                          |
| ------------------------ | ------------------------------------------------------------------------------------ |
| **From file**            | Select to specify the file path and name of the JSON file you want to load into PDI. |
| **File name**            | File path and name of the JSON file to load.                                         |
| **From field**           | Select to use an incoming field as the JSON file path.                               |
| **Field with file name** | The incoming field containing the JSON file path.                                    |

#### Output tab

![Hierarchical JSON Input step Output tab](/files/YZVBL9Icb0hCLCzAspym)

| Field                      | Description                                                                                                                                       |
| -------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Output field**           | Specify the field name for the output column.                                                                                                     |
| **Split rows across path** | Specify the JSON path to be parsed. See [Hierarchical data path specifications](broken://spaces/YwnJ6Fexn4LZwKRHghPK/pages/ji5ygWJ7r8yORvFw3Rjj). |

**Note:** **Split rows across path** is especially useful when loading JSON array objects within large JSON files.

#### Filters tab

![Hierarchical JSON Input step filters tab](/files/HBrFEX7HHlS3rPDG9dUZ)

Use **Path field** (optional) to specify the filters to apply while using **Split rows across path** to fetch a subset of a JSON file.

For details, see [Hierarchical data path specifications](broken://spaces/YwnJ6Fexn4LZwKRHghPK/pages/ji5ygWJ7r8yORvFw3Rjj).

### Examples

The following data is example JSON data in a file that you can load into PDI:

```
{
     "employees": [
           {
                    "name" : "emp_name_1" ,
                    "age" : 35,
                    "addresses" :[
                           {
                                  "country":"Country_1"
                           },
                           {
                                  "country":"Country_2"
                           }
                    ]
           },
           {
                    "name" : "emp_name_2",
                    "age" : 35,
                    "addresses" :[
                           {
                                  "country" :"Country_3"
                            },
                            {
                                  "country" :"Country_4"
                            {
                    ]
           }
     ]
}
```

#### Example 1

The following data is extracted from this JSON file when you set **Split rows across path** to `$.employees[*]` and do not specify any filters.

![Hierarchical JSON Input step example output](/files/yrXfEfqRNVsyrHeVytdF)

#### Example 2

If you configure the step with a split path of `$.employees[*]` and you want only the name and age fields, use filters of `$.name` and `$.age` on the **Filters** tab.

This produces two rows on the stream of the Hierarchical JSON Input step:

Row 1

```
 {
                    "name" : "emp_name_1" ,
                    "age" : 35
           }

```

Row 2

```
{
                    "name" : "emp_name_2",
                    "age" : 35
           }

```

#### Example 3

If you want a filtered entry in a single HDT row, leave **Split rows across path** blank, and use the filter paths:

```
$.employees[*].name
$.employees[*].age

```

This results in a single row with one HDT that does not have the input split:

```
{
     "employees": [
           {
                    "name" : "emp_name_1" ,
                    "age" : 35
           },
           {
                    "name" : "emp_name_2",
                    "age" : 35
           }
     ]
}

```


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