https://github.com/kgilmer/toj

Trees of JSON
https://github.com/kgilmer/toj

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Trees of JSON

• Host: GitHub
• URL: https://github.com/kgilmer/toj
• Owner: kgilmer
• License: apache-2.0
• Created: 2023-09-13T14:19:41.000Z (over 1 year ago)
• Default Branch: main
• Last Pushed: 2023-09-23T18:33:14.000Z (over 1 year ago)
• Last Synced: 2023-09-23T22:25:52.619Z (over 1 year ago)
• Language: Rust
• Size: 8.79 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Trees of JSON

Model projections from hierarchical parents in JSON

`toj` is a command-line tool that merges JSON documents in an assumed directory structure, starting from a parent document down to any number of specializations in subdirectories.  

Combining directory traversal with JSON merge logic, this simple tool allows for patterns like object-orientated inheritance, but for data. This may be useful in reducing redundancy in cases where a large number of model instances can be realized from a base general model in addition to one or more successive layers of specialization.

The merge strategy is to create the model from the top-most parent.  Children may Create (add new key/values), Update (specify new values for existing keys), and Delete (set a key's value to `null`) from parent data.

## Usage

```console

Usage: toj [OPTIONS] 

Arguments:

    

Options:

  -v, --verbose     See details

  -s, --skip-empty  Traverse to root of file system

  -h, --help        Print help

  -V, --version     Print version

```

## Example

### `animal-kingdom`

Given the following model hierarchy that describes some animals as JSON objects, in directories that specify habitats:

```text

j$ tree examples/animal-kingdom/

examples/animal-kingdom/

├── animal-model.json

├── forest

│   ├── alpine

│   │   └── animal-model.json

│   └── animal-model.json

├── ocean

│   └── animal-model.json

└── zoo

    └── animal-model.json

```

The base model that describes the superset of animals is in the top-most parent. 

`examples/animal-kingdom/animal-model.json`:

```json

{

    "animals" : {

        "deer" : {

            "avg-weight-kg" : 56,

            "leg-count": 4,

            "diet" : "herbivore"

        },

        "monkey" : {

            "avg-weight-kg" : 16,

            "leg-count": 2,

            "diet" : "herbivore"

        },

        "piranha" : {

            "avg-weight-kg" : 1,

            "leg-count": 0,

            "diet" : "carnivore"

        }      

    }

}

```

We can determine the concrete model projection of animals in any given habitat by merging the subset of models from the top-most parent (abstract) to the desired leaf (concrete):

```text

$ toj examples/animal-kingdom/forest/animal-model.json

{

  "animals": {

    "deer": {

      "avg-weight-kg": 56,

      "diet": "herbivore",

      "leg-count": 4

    },

    "monkey": {

      "avg-weight-kg": 16,

      "diet": "herbivore",

      "leg-count": 2

    }

  }

}

```

```text

$ toj examples/animal-kingdom/zoo/animal-model.json 

{

  "animals": {

    "monkey": {

      "avg-weight-kg": 20,

      "diet": "herbivore",

      "leg-count": 2

    },

    "piranha": {

      "avg-weight-kg": 2,

      "diet": "carnivore",

      "leg-count": 0

    }

  }

}

```

## Alternatives

### `jq`

The json tool `jq` can perform the JSON [object merging](https://stackoverflow.com/questions/19529688/how-to-merge-2-json-objects-from-2-files-using-jq), combined with shell scripts to perform directory traversal.