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ERC1155 metadata

Learn how to store ERC1155 metadata in a table.

Traditional NFTs are ERC721 tokens, which are non-fungible and unique. However, there are also ERC1155 tokens, which are semi-fungible and can be minted in batches such that multiple tokens can have the same metadata. This is useful for a number of use cases, such as a game inventory of NFT traits where you want to mint multiple tokens with the same metadata but different tokenIds.

Table data​

Similar to ERC721 metadata, you'll need to form a JSON object with ERC1155 compliance for each row in the table. The N below represents the token's id, and you can see that the format slightly differs from the ERC721 metadata format since a properties key with an object is used instead of an attributes array.

{
  "name": "Token #N",
  "image": "ipfs://QmVK.../N",
  "external_url": "https://example.com/N",
  "properties": {
    {
      "display_type": "string",
      "trait_type": "color",
      "value": "blue"
    }
  }
}

Thus, the table should have the following columns:

CREATE TABLE erc1155_metadata(
  id INTEGER,
  display_type TEXT,
  trait_type TEXT,
  value TEXT,
);

An example of the table data might look like this:

iddisplay_typetrait_typevalue
1stringshirtflannel
2stringhattrucker

Querying data​

To serve NFT metadata from a row in a table, you need to write a SQL statement that will:

  1. Extract the right row given a specific id (which should match with the NFT's tokenId).
  2. Convert the row into ERC1155 compliant JSON metadata.

We'll make use of nested json_object() functions and compose the data for a single token such that the <id> value represents the value of the ERC115 token.

SELECT
  json_object(
    'name',t.value||' #'||t.id,
    'external_url','https://example.com/'||t.id,
    'properties',
      json_object(
          'display_type','string',
          'trait_type',t.traitType,
          'value',t.value
      )
  )
FROM
  erc1155_metadata t
WHERE
  t.id = <id>
GROUP BY
  t.id;

Next steps​

Looking for more? Check out the page on how to build an NFT for more in-depth guides that include Solidity code examples.