Token metadata and URI in Blockchain / Solidity - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare the token URI variable.

Blockchain / Solidity

string private [1];

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Auri

Bmetadata

CtokenURI

DtokenId

Attempts:

3 left

💡 Hint

Common Mistakes

Using tokenId as the URI variable name

Using metadata which is too generic

Using tokenURI which is usually a function, not a variable

The token URI is usually stored in a variable named uri or similar. Here, uri is the private string holding the metadata URI.

2fill in blank

medium

Complete the function signature to return the token URI.

Blockchain / Solidity

function [1](uint256 tokenId) public view returns (string memory) {

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AgetTokenURI

BtokenURI

Curi

DmetadataURI

Attempts:

3 left

💡 Hint

Common Mistakes

Using getTokenURI which is not standard

Using uri which is usually a variable

Using metadataURI which is uncommon

The standard function to get a token's metadata URI in ERC721 is tokenURI.

3fill in blank

hard

Fix the error in the return statement to correctly return the token URI.

Blockchain / Solidity

return [1][tokenId];

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Auri

BtokenURI

Cmetadata

DtokenId

Attempts:

3 left

💡 Hint

Common Mistakes

Returning tokenURI which is a function

Returning tokenId which is a number, not a URI

Returning metadata which is undefined

The URI is stored in a mapping or variable named uri, so we return uri[tokenId].

4fill in blank

hard

Fill both blanks to declare and initialize the mapping for token URIs.

Blockchain / Solidity

mapping(uint256 => [1]) private [2];

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Astring

Buint256

Curi

DtokenURI

Attempts:

3 left

💡 Hint

Common Mistakes

Using uint256 as the value type

Using tokenURI as the mapping name

Using uint256 as the value type instead of string

The mapping stores a string URI for each token ID. The mapping name is uri.

5fill in blank

hard

Fill all three blanks to set the token URI in the function.

Blockchain / Solidity

function setTokenURI(uint256 tokenId, [1] memory [2]) public {
    [3][tokenId] = [2];
}

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Astring

Buri

DtokenURI

Attempts:

3 left

💡 Hint

Common Mistakes

Using tokenURI as parameter name

Using uint256 as parameter type

Using different names for parameter and mapping

The function takes a string memory uri parameter and sets uri[tokenId] to that value.