Reading an existing .json file written out using TinyDB

[tomwallis]

Apologies if this is a stupid question, but I have not seen the answer in your docs.

A colleague has passed me a .json file written out using TinyDB. I would like to read its contents. However, if I use

db = TinyDB('my_file.json')

then db is empty, and the file on disk is overwritten (contains one line {"_default": {}}). What's the correct way to read this file into a Python interpreter? I see no "load" method in the docs and tinydb.Storage.read doesn't do this.

[eugene-eeo]

Slightly weird question but is the JSON file valid? The last time I worked on the code we used a try..except block to test if files were empty, so if the file was manually modified and some minor issues were present (think missing quotes, unbalanced parens etc) then it would result in the same case as an empty file. So try loading it manually using json.loads to see if it works.

[tomwallis]

Ah, you seem to have it right.

import json
with open('my_file.json', 'r') as f:
    data = json.load(f)

/Users/user/miniconda3/envs/default/lib/python3.4/json/decoder.py in raw_decode(self, s, idx)
    357       
    358         try:
--> 359             obj, end = self.scan_once(s, idx)
    360         except StopIteration as err:
    361             raise ValueError(errmsg("Expecting value", s, err.value)) from None

ValueError: Expecting ',' delimiter: line 1 column 12582912 (char 12582911)

The .json file my colleague gave me appears to be invalid. Issue solved, but I suppose it would be helpful if tinyDB reported an error rather than silently overwriting the file.

[msiemens]

Actually I'd like to keep this open. TinyDB currently assumes that if the JSON module raises a ValueError, the database file was empty. But as in this case, that's a pretty shaky assumption and something I want to revisit for a potential v3.0.

[eugene-eeo]

Unhelpful but encouraging 👍 for looking into this issue.

[msiemens]

This should be closed in the 3.0 release, I just forgot to close this issue.