# Store Input

Once raw source data is stored in a [Zuar Runner
store](/jobs/io/store/), the Zuar Runner store itself can become
a source (input) in an IO job. 

.. image:: assets/store_input-1.png
   :alt: Connect to Zuar Runner Store

The primary use case for this is to create several related relational
database tables from a single nested data source (API data, JSON,
etc).

## Example Source Data

Let's use this accounting JSON data as an example:
```json
    [
      {
        "amount": 500.00,
        "customer": {
          "id": 1,
          "name": "Customer 1"
        },
        "id": 1,
        "invoice_lines": [
          {
            "amount": 200.00,
            "id": 1,
            "product": "A"
          },
          {
            "amount": 300.00,
            "id": 2,
            "product": "B"
          }
        ],
        "invoice_number": 1001
      },
      {
        "amount": 240.00,
        "customer": {
          "id": 1,
          "name": "Customer 2"
        },
        "id": 2,
        "invoice_lines": [
          {
            "amount": 200.00,
            "id": 1,
            "product": "A"
          },
          {
            "amount": 40.00,
            "id": 2,
            "product": "C"
          }
        ],
        "invoice_number": 1002
      }
    ]
```

This dataset has two arrays `[ ]`:

1. The data set as a whole is an array
2. The `invoice_lines` data contains an array

So, Zuar Runner needs to split this data into two relational database tables.

.. table:: Table 1 (invoice header)
   :widths: auto

   ===== ===============  ======   ==========   =============
   id    invoice_number   amount   cusomer_id   customer_name
   ===== ===============  ======   ==========   =============
   1     1001             500.00   1            Customer 1
   2     1002             240.00   2            Customer 2
   ===== ===============  ======   ==========   =============

**Table 1**, can be created using the [Zuar Runner JSON plugin](/jobs/json/).

Job #1 name: `json_invoices`


.. table:: Table 2 (invoice lines)
   :widths: auto

   =========== ==== ====== ========= =======
   invoice_id  id   line   product   amount
   =========== ==== ====== ========= =======
   1001        1    1      A         200.00   
   1001        2    2      B         300.00  
   1002        3    1      A         200.00  
   1002        4    2      C         40.00  
   =========== ==== ====== ========= =======

If Zuar Runner job #1 uses a [Zuar Runner store](/jobs/io/store/), then **Table 2**, can be created using a Zuar Runner Store job.

## Zuar Runner Store Job Config

Zuar Runner store jobs can be created using the [Generic plugin](/jobs/generic/).

Here's an example job config that pipes data from a Zuar Runner store.
```json
    {
        "input": {
            "name": "json_invoices",
            "use": "mitto.iov2.input#StoreInput",
            "jpath": "$.invoice_lines[*]",
            "members": [
                {
                    "name": "invoice_id",
                    "value": "$.id"
                }
            ]
        },
        "output": {
            "tablename": "invoice_lines",
            "use": "call:mitto.iov2.db#todb",
            "schema": "json",
            "dbo": "postgresql://db/analytics"
        },
        "steps": [
            {
                "use": "mitto.iov2.steps#Input",
                "transforms": [
                    {
                        "use": "mitto.iov2.transform#ExtraColumnsTransform"
                    },
                    {
                        "use": "mitto.iov2.transform#ColumnsTransform"
                    }
                ]
            },
            {
                "use": "mitto.iov2.steps#CreateTable"
            },
            {
                "use": "mitto.iov2.steps#Output",
                "transforms": [
                    {
                        "use": "mitto.iov2.transform#FlattenTransform"
                    }
                ]
            },
            {
                "use": "mitto.iov2.steps#CollectMeta"
            }
        ]
    }
```
The `input` section is the important part of this job config.

### Name

The `name` parameter is the name of the "parent" job that is configured to use a store.

### Jpath

The `jpath` parameter let's you define exactly what section of the
store's JSON data to pull from. This is necessary for **Table 2**
because of the nested data in the `invoice_lines` array. Learn more
about **JSONPath** (jpath) expressions below.

Query a record from the "parent" job's [Zuar Runner store
API](/jobs/io/store/#querying-the-mitto-store-api) to
determine the correct `jpath`.

### Members

The `members` parameter let's you add additional columns from any
section of the store's JSON data to the resulting database table. In
our case, we need to add the `id` of each **invoice** to the
`invoice_lines` table in order for us to join the two tables
together. `members` also uses jpath in it's `value` key, and you can
name the resulting column by adjusting the `name` key.

### JSONPath Expressions

To understand how to use JSONPath to pick specific sections of data
out of a JSON object you can visit:
[https://goessner.net/articles/JsonPath/](https://goessner.net/articles/JsonPath/)

To interactively create a JSON path, you can paste JSON into this GUI
and select fields until you obtain your desired level of detail:
[https://jsonpathfinder.com/](https://jsonpathfinder.com/). This tool
will help build you path.

To interactively learn or test how to use JSONPath syntax you can
visit: [https://jsonpath.com/](https://jsonpath.com/)

## Best Practices

Always run the store job after the "parent" job because the store job
requires the store from the "parent" job.