CODEWITHSUNDEEP
pythonjsonjsonschema
Elephant
Elephant

Reputation: 727

Filter JSON data against JSON schema in Python

I am looking for Python module to filter JSON data against schema.

For example, there is JSON data:

{
    "system" : {
        "state" : "enabled",
        "id" : 5,
        "keys" : [
            { "key_id": 12, "key": "filename.key" }
        ]
    }
}

And there is JSON schema:

{
    "system": {
        "id": "system",
        "required": true,
        "type": "object",
        "properties": {
            "state": {
                "id": "state",
                "required": true,
                "type": "string"
            },
            "id": {
                "id": "id",
                "required": true,
                "type": "number"
            }
        }
    }
}

As you can see, the schema does not contain "keys" property.

I need some tool, which could filter the JSON data using the schema and provide following JSON as an output:

{
    "system" : {
        "state" : "enabled",
        "id" : 5
    }
}

Upvotes: 5

Views: 1884

Answers (3)

Elephant
Elephant

Reputation: 727

Since there is no tool, for filtering JSON data against schema, I have resolved my task as follows.

Created template of expected JSON file. Actually it is already filtered JSON file, but without data.

{
    "system" : {
        "state" : "",
        "id" : 0
    }
}

Then go through the data file and the template file and just copy values from one to another for properties that exist in both files.

Upvotes: 2

lahiruk
lahiruk

Reputation: 443

Purpose of JSON schema is to validate given JSON input against a defined schema. As @Relequestual says in a comment you cannot use JSON schema to filter out fields directly.

If you need to remove only keys field then you do not need to use JSON schema at all. You could simply remove the field from JSON input.

In case you need to filter out a bunch of unexpected fields from the input you could use JSON schema to identify those fields. But you need to do filtering part manually or using another library since JSON schema cannot do that for you.

You could use additionalProperties field to restrict unexpected keys.

{
  "type":"object",
  "required":false,
  "properties":{
    "system": {
        "id": "system",
        "required": true,
        "type": "object",
        "properties": {
            "state": {
                "id": "state",
                "required": true,
                "type": "string"
            },
            "id": {
                "id": "id",
                "required": true,
                "type": "number"
            }
        },
        "additionalProperties": false
    }
  }
}

This will give a validation error like following

Message: Property 'keys' has not been defined and the schema does not allow additional properties. Schema path: #/properties/system/additionalProperties

This may not be the exact answer you are looking for. But hope it helps.

Upvotes: 1

bugsb
bugsb

Reputation: 129

You can use jsonschema to validate your json against the schema, check this example

from jsonschema import validate

schema = {"type" : "object","properties" : { "price" : {"type" : "number"},"name" : {"type" : "string"},},}
validate(instance={"name" : "Eggs", "price" : 34}, schema=schema)

If no exception is raised by validate(), the instance is valid

Upvotes: 1

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