# `prepare_metadata` lambda

The `prepare_metadata` lambda add information about existing common instances (genres, languages, countries) 
to the source json file and replaces it on S3 with new enriched version for the further steps. 

It only adds new fields, doesn't remove / update existing non-nullable fields, doesn't ingest any instance.
Raises: 
    HydrationException if it was impossible to match data from the input file with additional data to be set.
    PrepareMetadataException in case of general error.

All the changes are idempotent and backward compatible.



## Setup

### Install [`uv`](https://docs.astral.sh/uv/)

Choose your favourite or similar:

```shell
pip install uv
pipx install uv
brew install uv
```

### Permissions

Use [`awsume`](https://www.notion.so/AWS-Access-f841b9dd815d4443a80e96a86c92cd2f#5618a9119254428e9baeada414767e85):


```shell
awsume prod
```


### Install Packages

```shell
make uv_dev
```


### Copy and edit env and event.json shadows

```shell
cp event.shadow.json event.json
cp .env.shadow .env.shadow
```



## Local Development

```shell
# Install uv
brew install uv

# Install dependencies + create .venv (uv)
make uv_dev

# Run the function locally using event.json and print results
make dev

# Run formatting (ruff)
make fmt

# Run linting (ruff/mypy)
make lint

# Run unit tests (pytest)
make test_unit
```


## Local Development (Docker)

```shell
# Ensure the Docker daemon is running
docker ps

# Start the lambda container
make docker_up

# Send event.json to the local lambda container
make docker_event

# End the lambda container
make docker_down
```