Multichain Explorer server error

Question

Hi all,

I have 2 assets on my chain, when I try to view one of them there is no problem, but when I try to view the other I get this error from Multichain explorer.

Traceback (most recent call last):

  File "/usr/lib64/python2.7/wsgiref/handlers.py", line 85, in run

    self.result = application(self.environ, self.start_response)

  File "/home/demo/multichain-explorer/Mce/abe.py", line 349, in __call__

    tvars['body'] = flatten(page['body'])

  File "/home/demo/multichain-explorer/Mce/abe.py", line 4018, in flatten

    return ''.join(map(flatten, l))

  File "/home/demo/multichain-explorer/Mce/abe.py", line 4018, in flatten

    return ''.join(map(flatten, l))

  File "/home/demo/multichain-explorer/Mce/abe.py", line 4023, in flatten

    return l.decode('unicode-escape')

UnicodeDecodeError: 'unicodeescape' codec can't decode byte 0x5c in position 0: \ at end of string

127.0.0.1 - - [28/Jul/2017 10:22:55] "GET /FundPlaces/assetref/1884-1385-19420 HTTP/1.1" 500 59

Not sure why this is happening. Does anyone have any idea?

Comments

Hmmm... is it possible you're using some non-English letters in your asset names? This is legal from MultiChain's perspective but might be tripping up the Explorer.

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For asset names we use md5 hashes could it be the metadata?

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Yes, it could be. Does that contain non-ASCII characters?

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This is the asset issuance metadata. I got it from viewing transactions. It's basically JSON encoded data where everything is a string. It should not have any non ascii characters. This is the metadata

https://explorer.fundplaces.com/FundPlaces/tx/dc4b924f66374c3f14cad2d812a70669120e6d9234f4a680cd16302da695aea1

This is where the server error occurs:

https://explorer.fundplaces.com/FundPlaces/assetref/1884-1385-19420

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Hi Multichain or anyone else,

I really need the explorer to work, can you help me to get this working?

Answer 1

Are you adding an array of chars to issue details? or is python doing something here?

In mine details of issuefirst I have

"details": {
                "PublishedDate": "xxx",
                "Price": "xxx"
            }

https://explorer.fundplaces.com/FundPlaces/rpctxjson/dc4b924f66374c3f14cad2d812a70669120e6d9234f4a680cd16302da695aea1

  "issue": {
    "details": {
      "0": "{",
      "1": """,
      "10": "n",

... etc

Answer 2

We need to look into why the Explorer is failing on this, but in general it looks like you're adding your metadata in a very strange way. You have a large object with integers as field name and individual characters as field values. Instead you should put the entire JSON structure you want to store as a string in a single field. I'm guessing the problem in the Explorer is that a field name contains an integer, so if you do this it should solve the problem.

Answer 3

Hi all,

Just to square the circle, yes, there were some errors in the way I was storing the metadata (double json encode). However, since the chain is "live", I'm not able to change the metadata.

Therefore, I made a small tweak to the codebase of the multichain explorer to basically catch the exception and return an empty string instead:

   4016 def flatten(l):
   4017     if isinstance(l, list):
   4018         try:
   4019             return ''.join(map(flatten, l))
   4020         except:
   4021             return '';