# read_json

Tip

If you are receiving newline-delimited JSON (NDJSON), use [`read_ndjson`](https://preview.docs.tenzir.com/375/375/reference/operators/read_ndjson.md) instead.

Parses an incoming JSON stream into events.

```tql
read_json [schema=string, selector=string, schema_only=bool, merge=bool, raw=bool,
           unflatten_separator=string, arrays_of_objects=bool]
```

## Description

Parses an incoming JSON byte stream into events.

### `merge = bool (optional)`

Merges all incoming events into a single schema\* that converges over time. This option is usually the fastest *for reading* highly heterogeneous data, but can lead to huge schemas filled with nulls and imprecise results. Use with caution.

\*: In selector mode, only events with the same selector are merged.

In merging mode, a repeated key will always overwrite the previous value.

### `raw = bool (optional)`

Use only the raw types that are native to the parsed format. Fields that have a type specified in the chosen `schema` will still be parsed according to the schema.

### `schema = string (optional)`

Provide the name of a schema to be used by the parser.

If a schema with a matching name is installed, the result will always have all fields from that schema.

* Fields that are specified in the schema, but did not appear in the input will be null.
* Fields that appear in the input, but not in the schema will also be kept. Use `schema_only=true` to reject fields that are not in the schema.

If the given schema does not exist, this option instead assigns the output schema name only.

The `schema` option is incompatible with the `selector` option.

### `selector = string (optional)`

Designates a field value as schema name with an optional dot-separated prefix.

The string is parsed as `<fieldname>[:<prefix>]`. The `prefix` is optional and will be prepended to the field value to generate the schema name.

For example, the Suricata EVE JSON format includes a field `event_type` that contains the event type. Setting the selector to `event_type:suricata` causes an event with the value `flow` for the field `event_type` to map onto the schema `suricata.flow`.

The `selector` option is incompatible with the `schema` option.

### `schema_only = bool (optional)`

When working with an existing schema, this option will ensure that the output schema has *only* the fields from that schema.

If the schema name is obtained via a `selector` and it does not exist, this has no effect.

This option requires either `schema` or `selector` to be set.

### `unflatten_separator = string (optional)`

A delimiter that, if present in keys, causes values to be treated as values of nested records.

A popular example of this is the [Zeek JSON](https://preview.docs.tenzir.com/375/375/reference/operators/read_zeek_json.md) format. It includes the fields `id.orig_h`, `id.orig_p`, `id.resp_h`, and `id.resp_p` at the top-level. The data is best modeled as an `id` record with four nested fields `orig_h`, `orig_p`, `resp_h`, and `resp_p`.

Without an unflatten separator, the data looks like this:

Without unflattening

```json
{
  "id.orig_h": "1.1.1.1",
  "id.orig_p": 10,
  "id.resp_h": "1.1.1.2",
  "id.resp_p": 5
}
```

With the unflatten separator set to `.`, Tenzir reads the events like this:

With 'unflatten'

```json
{
  "id": {
    "orig_h": "1.1.1.1",
    "orig_p": 10,
    "resp_h": "1.1.1.2",
    "resp_p": 5
  }
}
```

### Duplicate Keys

If the parser encounters a duplicate key in an event, it will transparently upgrade the field to be a list of values instead.

For a simple example, consider this JSON file:

Duplicate Keys

```json
{"key": 7}
{"key": 0.0, "key": 1}
{"key": 42}
```

```tql
{key: 7}
{key: [0.0, 1.0]}
{key: 42}
```

If the values are of different type, conversions to a common type will be attempted, such as to a common number type. Ultimately values will be stringified if they do not share a common type:

Type Conflict

```json
{"key": 0.0, "key": "1.1.1.1", "key": "example.com"}
```

```tql
{key: ["0", "1.1.1.1", "example.com"]}
```

### `arrays_of_objects = bool (optional)`

Default: `false`.

Parse arrays of objects, with every object in the outermost arrays resulting in one event each. This is particularly useful when interfacing with REST APIs, which often yield large arrays of objects instead of newline-delimited JSON objects.

## Examples

### Read a JSON file

input.json

```json
{
  "product": "Tenzir",
  "version.major": 4,
  "version.minor": 22
}
{
  "product": "Tenzir",
  "version.major": 4,
  "version.minor": 21,
  "version.dirty": true
}
```

Pipeline

```tql
from_file "events.json" {
  read_json unflatten="."
}
```

Output

```json
{
  "product": "Tenzir",
  "version": {
    "major": 4,
    "minor": 22
  }
}
{
  "product": "Tenzir",
  "version": {
    "major": 4,
    "minor": 21,
    "dirty": true
  }
}
```

### Read a JSON array

[JA4+](https://ja4db.com/) provides fingerprints via a REST API, which returns a single JSON array.

Example Input

```json
[
  {
    "application": "SemrushBot",
    "library": null,
    "device": null,
    "os": "Other",
    "user_agent_string": null,
    "certificate_authority": null,
    "observation_count": 449,
    "verified": false,
    "notes": null,
    "ja4_fingerprint": "t13d301000_01455d0db58d_5ac7197df9d2",
    "ja4_fingerprint_string": null,
    "ja4s_fingerprint": null,
    "ja4h_fingerprint": "ge11nn100000_c910c42e1704_e3b0c44298fc_e3b0c44298fc",
    "ja4x_fingerprint": null,
    "ja4t_fingerprint": null,
    "ja4ts_fingerprint": null,
    "ja4tscan_fingerprint": null
  },
  {
    "application": null,
    "library": null,
    "device": "Epson Printer",
    "os": null,
    "user_agent_string": null,
    "certificate_authority": null,
    "observation_count": 1,
    "verified": true,
    "notes": null,
    "ja4_fingerprint": null,
    "ja4s_fingerprint": null,
    "ja4h_fingerprint": null,
    "ja4x_fingerprint": null,
    "ja4t_fingerprint": null,
    "ja4ts_fingerprint": null,
    "ja4tscan_fingerprint": "28960_2-4-8-1-3_1460_3_1-4-8-16"
  },
  ...
]
```

You can easily ingest this into Tenzir using

Pipeline

```tql
load "https://ja4db.com/api/read/"
read_json arrays_of_objects=true
```

Example Output

```json
{
  "application": "SemrushBot",
  "library": null,
  "device": null,
  "os": "Other",
  "user_agent_string": null,
  "certificate_authority": null,
  "observation_count": 449,
  "verified": false,
  "notes": null,
  "ja4_fingerprint": "t13d301000_01455d0db58d_5ac7197df9d2",
  "ja4_fingerprint_string": null,
  "ja4s_fingerprint": null,
  "ja4h_fingerprint": "ge11nn100000_c910c42e1704_e3b0c44298fc_e3b0c44298fc",
  "ja4x_fingerprint": null,
  "ja4t_fingerprint": null,
  "ja4ts_fingerprint": null,
  "ja4tscan_fingerprint": null
},
{
  "application": null,
  "library": null,
  "device": "Epson Printer",
  "os": null,
  "user_agent_string": null,
  "certificate_authority": null,
  "observation_count": 1,
  "verified": true,
  "notes": null,
  "ja4_fingerprint": null,
  "ja4s_fingerprint": null,
  "ja4h_fingerprint": null,
  "ja4x_fingerprint": null,
  "ja4t_fingerprint": null,
  "ja4ts_fingerprint": null,
  "ja4tscan_fingerprint": "28960_2-4-8-1-3_1460_3_1-4-8-16"
}
```

## See Also

* [`parse_json`](https://preview.docs.tenzir.com/375/375/reference/functions/parse_json.md)
* [`read_ndjson`](https://preview.docs.tenzir.com/375/375/reference/operators/read_ndjson.md)
* [`write_json`](https://preview.docs.tenzir.com/375/375/reference/operators/write_json.md)
* [Convert data formats](https://preview.docs.tenzir.com/375/375/guides/transformation/convert-data-formats.md)