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Adding a datahub source type

A datahub source is any custom file source that can be imported into a Knowledge Base. A datahub source converts your source into files. An example source is reading from a SQL database and writing the data as text to a file. First we define a config class, this contains the configuration for the source. The config class must inherit from CustomSourceConfig, and must implement the to_files method. 
from noxus.datahub import CustomSourceConfig


class SQLConfigSource(CustomSourceConfig):
    url: str = Parameter(
        default="",
        display=ConfigDynamicText(
            label="SQL URL: e.g. postgresql://username:password@hostname:5432/database"
        ),
    )
    table: str = Parameter(
        default="",
        display=ConfigDynamicText(label="Name of the table to ingest"),
    )

    async def to_files(
        self,
        ctx: ExecutionContext,
        subtype: str,
    ) -> list[File]:
        text_content = ... # snipped for brevity
        file_name = f"{self.table}.txt" # we can read configuration values
        async with ctx.db() as db:
            return [
                await File.from_bytes_spot_uri( # write the output to a file.
                    db,
                    ctx.storage,
                    data=text_content.encode(),
                    name=file_name,
                    group=ctx.group,
                    content_type="text/plain",
                )
            ]
Next we define a source class, this contains the subtype, name, image, and config class. The subtype must be unique across all sources. These values will be visible in our UI when selecting a source. 
class SQLSource(CustomSource[SQLConfigSource]):
    source_type: SourceType = SourceType.Custom
    subtype: str | None = "sql"

    config_cls: Type[SQLConfigSource] = SQLConfigSource
    config: SQLConfigSource
    image: str = "https://cdn-icons-png.flaticon.com/128/2906/2906274.png"
    name: str = "SQL"
The final step is to return the source in the datahub_sources method of your plugin.