csv-converter 0.0.7
Tool to convert CSV files based on JSON config.

A simple tool that uses a JSON config file (or a config dict) to convert one CSV to another. Tested up to Python 3.8.

Simplest use case is to just list the new headers and link them to the old headers, like so:

```json
{
"New Column Header One": "Old Column Header One",
"New Column Header Two": "Old Column Header Two"
}
```

A slightly more useful version specifies a default to use (implemented using the "or" operator `value_from_old_column or default`):

```json
{
  "New Header One": {
    "old_column": "Old Header One",
    "default": "DEFAULT VALUE FOR ONE"
  },
  "New Header Two": {
    "old_column": "Old Header Two",
    "default": "DEFAULT VALUE FOR TWO"
  }
}
```

The third and final currently implemented option is to use a lambda function (use of full functions is planned):

```json
{
  "New Header One": {
    "old_column": "Old Header One",
    "default": "DEFAULT FOR ONE",
    "lambda": "lambda a, b: str(a.get(b.get('old_column'))).lower()"
  },
  "New Header Two": {
    "old_column": "Old Header Two",
    "default": "DEFAULT FOR TWO",
    "lambda": "lambda a, b: str(a.get(b.get('old_column'))).lower()"
  }
}
```

It will run the lambda as:

```python
item['lambda'] = "lambda a, b: str(a.get(b.get('old_column'))).lower()"
exec(f"c = {item.get('lambda')}", globals())
return c(line, item)
```

Where `line` is the current line of the source CSV, and `item` is the current element from the JSON file (the current column).

## Usage: 

```python
from csv_converter import CSVConverter
converter = CSVConverter(config_file_name='path-to-config.json')
output = converter.convert(input_file_name='path-to-source.csv')

# For multiple files, either feed them in as a list:
output = converter.convert(input_file_name=['path-to-file-one.csv', 'path-to-file-two.csv'])

#or re-use the same converter with the "append_mode" flag set to True -- this will make it remember all previous files
converter = CSVConverter(config_file_name='path-to-config.json', append_mode=True)
output_of_file_one = converter.convert(input_file_name='path-to-file-one.csv')
output_of_file_one_and_two = converter.convert(input_file_name='path-to-file-two.csv')

```


## Input Config

This goes at the same level as the headers, with the special name "$input_config$"

This supports setting the file format type. Useful if importing an xlsx file that for some reason doesn't have
the right filename. Use `format` for this.

Can also be used to specify which line the header is actually on.

`header_line_number` is one indexed to line up with the numbers on spreadsheet software.

`header_hints` is a list of strings that should match to help find the header.

If both are specified, it will start looking for the header line on the line specified.

```json
{
  "$input_config$": {
      "format": "xlsx", // "ods" to be supported later.
      "header_line_number": 3,
      "header_hints": ["Old Header Zero", "Old Header One"],
      "header_hints_in_order": null, // not implemented yet
      "header_hints_together": null // not implemented yet
  },
  "New Header Zero": {
    "old_column": "Old Header Zero",
    "default": "DEFAULT FOR ZERO"
  }
}
```


## JSON Config Generator

A basic config can be generated from a template csv file. This is useful for example 
when importing product data to a shop. Simply run:

```python
from csv_converter import CSVConverter
CSVConverter(no_config=True).generate_json_headers(input_file_name="import-template.csv",
                                                   output_file_name="import-config.json")
```

This will create a file called "import-config.json" that will map all the headers in 
"import-template.csv" to themselves, allowing you to easily go through each one and 
change the "old_column" values where needed to match your raw data.