# 4 CSV to JSON preprocessing

#### Overview

In this preprocessing step it is possible to convert CSV file data into
JSON format. It's supported in:

-   items (item prototypes)
-   low-level discovery rules

#### Configuration

To configure a CSV to JSON preprocessing step:

-   Go to the Preprocessing tab in
    [item](/manual/config/items/item#item_value_preprocessing)/[discovery
    rule](/manual/discovery/low_level_discovery#preprocessing)
    configuration
-   Click on *Add*
-   Select the *CSV to JSON* option

![](../../../../assets/en/manual/appendix/csv_to_json_params0.png){width="600"}

The first parameter allows to set a custom delimiter. Note that if the
first line of CSV input starts with "Sep=" and is followed by a single
UTF-8 character then that character will be used as the delimiter in
case the first parameter is not set. If the first parameter is not set
and a delimiter is not retrieved from the "Sep=" line, then a comma is
used as a separator.

The second optional parameter allows to set a quotation symbol.

If the *With header row* checkbox is marked, the header line values will
be interpreted as column names (see [Header
processing](#csv_header_processing) for more information).

If the *Custom on fail* checkbox is marked, the item will not become
unsupported in case of a failed preprocessing step. Additionally custom
error handling options may be set: discard the value, set a specified
value or set a specified error message.

#### Header processing

The CSV file header line can be processed in two different ways:

-   If the *With header row* checkbox is marked - header line values are
    interpreted as column names. In this case the column names must be
    unique and the data row should not contain more columns than the
    header row;
-   If the *With header row* checkbox is not marked - the header line is
    interpreted as data. Column names are generated automatically
    (1,2,3,4...)

CSV file example:

    Nr,Item name,Key,Qty
    1,active agent item,agent.hostname,33
    "2","passive agent item","agent.version","44"
    3,"active,passive agent items",agent.ping,55

::: noteclassic
A quotation character within a quoted field in the input
must be escaped by preceding it with another quotation
character.
:::

**Processing header line**

JSON output when a header line is expected:

``` {.json}
[
   {
      "Nr":"1",
      "Item name":"active agent item",
      "Key":"agent.hostname",
      "Qty":"33"
   },
   {
      "Nr":"2",
      "Item name":"passive agent item",
      "Key":"agent.version",
      "Qty":"44"
   },
   {
      "Nr":"3",
      "Item name":"active,passive agent items",
      "Key":"agent.ping",
      "Qty":"55"
   }
]
```

**No header line processing**

JSON output when a header line is not expected:

``` {.json}
[
   {
      "1":"Nr",
      "2":"Item name",
      "3":"Key"
      "4":"Qty"
   },
   {
      "1":"1",
      "2":"active agent item",
      "3":"agent.hostname"
      "4":"33"
   },
   {
      "1":"2",
      "2":"passive agent item",
      "3":"agent.version"
      "4":"44"
   },
   {
      "1":"3",
      "2":"active,passive agent items",
      "3":"agent.ping"
      "4":"55"
   }
]
```