Why the json.decoder.JSONDecodeError?

Question

I'm trying to configure my Python logging module using logging.config.dictConfig()

However, my JSON file appears to be corrupt even though it works as a Python dict with false changed to False, so I don't think it's a syntax error.

My code says:

import json

with open('logging_config.json') as f:
    d = json.load(f)

My logging_config.json file is:

{
  "version": 1,
  "disable_existing_loggers": false,
  "formatters": {
    "standard": {
      "format": "[%(levelname)s] %(name)s: %(message)s"
    },
  },
  "handlers": {
    "default": {
      "level": "DEBUG",
      "formatter": "standard",
      "class": "logging.StreamHandler",
    },
  },
  "loggers": {
    "": {
      "handlers": ["default"],
      "level": "INFO",
      "propagate": true
    },
    "myfunc": {
      "handlers": ["default"],
      "level": "DEBUG",
      "propagate": false
    },
  }
}

When I run that simple program, I get an error: json.decoder.JSONDecodeError: Expecting property name enclosed in double quotes: line 8 column 3 (char 156)

What could be causing the JSON decoder to fail?

Thanks in advance for any help.

The JSON parser is expecting a certain type of value for each key. A string is one accepted value, an integer another. You're trying to insert a boolean, but there is a difference between upper and lowercase for booleans. Only one is a valid boolean. Here's some documentation — ajoseps
– ajoseps, Commented Aug 22, 2017 at 16:01
@ajoseps that isn't the issue. The issue is you have an extraneous comma, so JSON expects a key. How was this JSON generated? It certainly wasn't by the python json module — juanpa.arrivillaga
– juanpa.arrivillaga, Commented Aug 22, 2017 at 16:03
It used to be a Python dict which I converted manually. Python forgives the extra commas but json doesn't — blokeley
– blokeley, Commented Aug 22, 2017 at 16:14

wkl · Accepted Answer · 2017-08-22 16:07:32Z

8

You have multiple extraneous commas which will break the JSON deserialization.

Here's your original JSON with every extraneous comma pointed out:

{
  "version": 1,
  "disable_existing_loggers": false,
  "formatters": {
    "standard": {
      "format": "[%(levelname)s] %(name)s: %(message)s"
    }, # <--- extraneous comma
  },
  "handlers": {
    "default": {
      "level": "DEBUG",
      "formatter": "standard",
      "class": "logging.StreamHandler", # <--- extraneous comma
    }, # <--- extraneous comma
  },
  "loggers": {
    "": {
      "handlers": ["default"],
      "level": "INFO",
      "propagate": true
    },
    "myfunc": {
      "handlers": ["default"],
      "level": "DEBUG",
      "propagate": false
    }, # <--- extraneous comma
  }
}

Removing those, this is now a valid JSON document:

{
    "version": 1,
    "disable_existing_loggers": false,
    "formatters": {
        "standard": {
            "format": "[%(levelname)s] %(name)s: %(message)s"
        }
    },
    "handlers": {
        "default": {
            "level": "DEBUG",
            "formatter": "standard",
            "class": "logging.StreamHandler"
        }
    },
    "loggers": {
        "": {
            "handlers": ["default"],
            "level": "INFO",
            "propagate": true
        },
        "myfunc": {
            "handlers": ["default"],
            "level": "DEBUG",
            "propagate": false
        }
    }
}

answered Aug 22, 2017 at 16:07

wkl

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1 Comment

blokeley Over a year ago

Ah, Python forgives these extra commas. I missed them when converting the Python to json. Thanks

Haroldo_OK · Accepted Answer · 2017-08-22 16:21:46Z

2

As others already answered, there are some excess commas in your JSON.

You could feed your JSON to https://jsonlint.com/ ; it tends to give more useful help messages.

answered Aug 22, 2017 at 16:21

Haroldo_OK

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Comments

nick_gabpe · Accepted Answer · 2017-08-22 16:07:53Z

1

This happens because your JSON is invalid. this one JSON is valid. I removed extra commas from your JSON. You can use any JSON validator to fix it.

{
  "version": 1,
  "disable_existing_loggers": false,
  "formatters": 
  {
    "standard": 
    {
      "format": "[%(levelname)s] %(name)s: %(message)s"
    }
  },
  "handlers": 
  {
    "default": 
    {
      "level": "DEBUG",
      "formatter": "standard",
      "class": "logging.StreamHandler"
    }
  },
  "loggers": 
  {
    "": 
    {
      "handlers": ["default"],
      "level": "INFO",
      "propagate": true
    },
    "myfunc": 
    {
      "handlers": ["default"],
      "level": "DEBUG",
      "propagate": false
    }
  }
}

answered Aug 22, 2017 at 16:07

nick_gabpe

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