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

# JSON file gem for Data Analysis

> Read and write JSON files

This page describes the **JSON-specific properties** that appear in the **Properties** tab of Source and Target gems. These settings are the same for JSON files regardless of which connection type is configured in the gem (for example, S3, SFTP, or SharePoint).

If you need details on configuring a Source or Target gem end to end (including all tabs such as **Location**), see the documentation for the specific file storage connection.

<Info>
  You can also use the [upload file](/data-analysis/gems/source-target/table/upload-files) feature
  to use JSON files. These will be stored in the SQL warehouse configured in your fabric.
</Info>

## Properties

### Source properties

The following properties are available for the JSON Source gem.

| Property                      | Description                                                                                                                                                                                                                 | Default |
| ----------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------- |
| Schema                        | Define the structure of your data. This includes the column names and the data type for each column (such as String, Integer, etc.).<br /><br />Click **Infer Schema** to automatically detect the structure from the file. | None    |
| Description                   | Add a description of the table.<br /><br />Click **Auto-description** to automatically generate the description.                                                                                                            | None    |
| Multiple documents per file   | Select whether the file contains multiple JSON objects separated by newline.                                                                                                                                                | False   |
| Inference Data Sampling Limit | Define the maximum number of rows to sample for inferring the schema. Set to `0` to use all rows.                                                                                                                           | `0`     |

### Target properties

The following properties are available for the JSON Target gem.

| Property                    | Description                                                                                                      | Default |
| --------------------------- | ---------------------------------------------------------------------------------------------------------------- | ------- |
| Schema                      | Review the structure of your data. Prophecy automatically detects the schema from the input gem.                 | None    |
| Description                 | Add a description of the table.<br /><br />Click **Auto-description** to automatically generate the description. | None    |
| Multiple documents per file | Select whether the file will contain multiple JSON objects separated by newline.                                 | False   |
| Enable indentation          | Select whether to format the JSON output with indentation for readability.                                       | False   |
| Indentation size            | Define the number of spaces to use for each indentation level when indentation is enabled.                       | `2`     |
| Escape HTML characters      | Select whether to escape HTML characters (such as `<`, `>`, and `&`) in the JSON output.                         | True    |

## Schema validation

Prophecy lets you enable schema validation for JSON files in a Source gem. Use schema validation to ensure JSON files conform to a predefined structure before ingesting the data. JSON schema validation works for all file storage connections.

### Prerequisites

To use schema validation, you need a JSON Schema file in the same directory as your source file. If your schema uses `$ref` to reference external schemas, those referenced schema files must also be in the same directory. Learn how to [write JSON Schema files](https://json-schema.org/learn).

### Set up schema validation

1. In the Location tab of a Source gem, toggle **Enable JSON Schema Validation**.
2. Provide a path to the JSON file that you will use to validate against.
3. Open the Properties tab.
4. Click **Infer Schema**.

If the source file schema matches the validation schema, schema inference will run successfully.

### Example

The following example shows a source file and a corresponding validation file that would validate successfully.

<CodeGroup>
  ```json users.json theme={null}
  {
    "id": 1,
    "name": "John Doe",
    "email": "john.doe@example.com"
  }
  ```

  ```json users-schema.json theme={null}
  {
    "$schema": "http://json-schema.org/draft-07/schema#",
    "type": "object",
    "properties": {
      "id": {
        "type": "integer"
      },
      "name": {
        "type": "string"
      },
      "email": {
        "type": "string",
        "format": "email"
      }
    },
    "required": ["id", "name", "email"]
  }
  ```
</CodeGroup>

### Troubleshooting

If the schemas do not match:

* Schema inference will fail.
* The Source gem will fail to run.

To troubleshoot, look for the error in the [runtime logs](/data-analysis/development/runs/runtime-logs). Here is an example error:

```text wrap theme={null}
Failed due to error in "OrchestrationSource_0". Error: JSON validation failed against JSON schema for file /Volumes/pipelinehub/dev/json-schema-validate/users.json: 1.data: Additional property location is not allowed; 1.data: Additional property lastLogin is not allowed
```