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SerializeMetadata

import ViewResolver from 0x1d7e57aa55817448 import MetadataViews from 0x1d7e57aa55817448 import NonFungibleToken from 0x1d7e57aa55817448 import FungibleTokenMetadataViews from 0xf233dcee88fe0abe import Serialize from 0x1e4aa0b87d10b141 /// This contract defines methods for serializing NFT metadata as a JSON compatible string, according to the common /// OpenSea metadata format. NFTs and metadata views can be serialized by reference via contract methods. /// access(all) contract SerializeMetadata { /// Serializes the metadata (as a JSON compatible String) for a given NFT according to formats expected by EVM /// platforms like OpenSea. If you are a project owner seeking to expose custom traits on bridged NFTs and your /// Trait.value is not natively serializable, you can implement a custom serialization method with the /// `{SerializableStruct}` interface's `serialize` method. /// /// Reference: https://docs.opensea.io/docs/metadata-standards /// /// /// @returns: A JSON compatible data URL string containing the serialized display & collection display views as: /// `data:application/json;utf8,{ /// \"name\": \"<display.name>\", /// \"description\": \"<display.description>\", /// \"image\": \"<display.thumbnail.uri()>\", /// \"external_url\": \"<nftCollectionDisplay.externalURL.url>\", /// \"attributes\": [{\"trait_type\": \"<trait.name>\", \"value\": \"<trait.value>\"}, {...}] /// }` access(all) fun serializeNFTMetadataAsURI(_ nft: &{NonFungibleToken.NFT}): String { // Serialize the display values from the NFT's Display & NFTCollectionDisplay views let nftDisplay = nft.resolveView(Type<MetadataViews.Display>()) as! MetadataViews.Display? let collectionDisplay = nft.resolveView(Type<MetadataViews.NFTCollectionDisplay>()) as! MetadataViews.NFTCollectionDisplay? let display = self.serializeFromDisplays(nftDisplay: nftDisplay, collectionDisplay: collectionDisplay) // Get the Traits view from the NFT, returning early if no traits are found let traits = nft.resolveView(Type<MetadataViews.Traits>()) as! MetadataViews.Traits? let attributes = self.serializeNFTTraitsAsAttributes(traits ?? MetadataViews.Traits([])) // Return an empty string if nothing is serializable if display == nil && attributes == nil { return "" } // Init the data format prefix & concatenate the serialized display & attributes var serializedMetadata = "data:application/json;utf8,{" if display != nil { serializedMetadata = serializedMetadata.concat(display!) } if display != nil && attributes != nil { serializedMetadata = serializedMetadata.concat(", ") } if attributes != nil { serializedMetadata = serializedMetadata.concat(attributes) } return serializedMetadata.concat("}") } /// Serializes the display & collection display views of a given NFT as a JSON compatible string. If nftDisplay is /// present, the value is returned as token-level metadata. If nftDisplay is nil and collectionDisplay is present, /// the value is returned as contract-level metadata. If both values are nil, nil is returned. /// /// @param nftDisplay: The NFT's Display view from which values `name`, `description`, and `thumbnail` are serialized /// @param collectionDisplay: The NFT's NFTCollectionDisplay view from which the `externalURL` is serialized /// /// @returns: A JSON compatible string containing the serialized display & collection display views as either: /// \"name\": \"<nftDisplay.name>\", \"description\": \"<nftDisplay.description>\", \"image\": \"<nftDisplay.thumbnail.uri()>\", \"external_url\": \"<collectionDisplay.externalURL.url>\", /// \"name\": \"<collectionDisplay.name>\", \"description\": \"<collectionDisplay.description>\", \"image\": \"<collectionDisplay.squareImage.file.uri()>\", \"external_link\": \"<collectionDisplay.externalURL.url>\", /// access(all) fun serializeFromDisplays(nftDisplay: MetadataViews.Display?, collectionDisplay: MetadataViews.NFTCollectionDisplay?): String? { // Return early if both values are nil if nftDisplay == nil && collectionDisplay == nil { return nil } // Initialize JSON fields let name = "\"name\": " let description = "\"description\": " let image = "\"image\": " let externalURL = "\"external_url\": " let externalLink = "\"external_link\": " var serializedResult = "" // Append results from the token-level Display view to the serialized JSON compatible string if nftDisplay != nil { serializedResult = serializedResult .concat(name).concat(Serialize.tryToJSONString(nftDisplay!.name)!).concat(", ") .concat(description).concat(Serialize.tryToJSONString(nftDisplay!.description)!).concat(", ") .concat(image).concat(Serialize.tryToJSONString(nftDisplay!.thumbnail.uri())!) // Append the `externa_url` value from NFTCollectionDisplay view if present if collectionDisplay != nil { return serializedResult.concat(", ") .concat(externalURL).concat(Serialize.tryToJSONString(collectionDisplay!.externalURL.url)!) } } if collectionDisplay == nil { return serializedResult } // Without token-level view, serialize as contract-level metadata return serializedResult .concat(name).concat(Serialize.tryToJSONString(collectionDisplay!.name)!).concat(", ") .concat(description).concat(Serialize.tryToJSONString(collectionDisplay!.description)!).concat(", ") .concat(image).concat(Serialize.tryToJSONString(collectionDisplay!.squareImage.file.uri())!).concat(", ") .concat(externalLink).concat(Serialize.tryToJSONString(collectionDisplay!.externalURL.url)!) } /// Serializes given Traits view as a JSON compatible string. If a given Trait is not serializable, it is skipped /// and not included in the serialized result. /// /// @param traits: The Traits view to be serialized /// /// @returns: A JSON compatible string containing the serialized traits as: /// `\"attributes\": [{\"trait_type\": \"<trait.name>\", \"value\": \"<trait.value>\"}, {...}]` /// access(all) fun serializeNFTTraitsAsAttributes(_ traits: MetadataViews.Traits): String { // Serialize each trait as an attribute, building the serialized JSON compatible string var serializedResult = "\"attributes\": [" let traitsLength = traits.traits.length for i, trait in traits.traits { let value = Serialize.tryToJSONString(trait.value) if value == nil { // Remove trailing comma if last trait is not serializable if i == traitsLength - 1 && serializedResult[serializedResult.length - 1] == "," { serializedResult = serializedResult.slice(from: 0, upTo: serializedResult.length - 1) } continue } serializedResult = serializedResult.concat("{") .concat("\"trait_type\": ").concat(Serialize.tryToJSONString(trait.name)!) .concat(", \"value\": ").concat(value!) .concat("}") if i < traits!.traits.length - 1 { serializedResult = serializedResult.concat(",") } } return serializedResult.concat("]") } /// Serializes the FTDisplay view of a given fungible token as a JSON compatible data URL. The value is returned as /// contract-level metadata. /// /// @param ftDisplay: The tokens's FTDisplay view from which values `name`, `symbol`, `description`, and /// `externaURL` are serialized /// /// @returns: A JSON compatible data URL string containing the serialized view as: /// `data:application/json;utf8,{ /// \"name\": \"<ftDisplay.name>\", /// \"symbol\": \"<ftDisplay.symbol>\", /// \"description\": \"<ftDisplay.description>\", /// \"external_link\": \"<ftDisplay.externalURL.url>\", /// }` access(all) fun serializeFTDisplay(_ ftDisplay: FungibleTokenMetadataViews.FTDisplay): String { let name = "\"name\": " let symbol = "\"symbol\": " let description = "\"description\": " let externalLink = "\"external_link\": " return "data:application/json;utf8,{" .concat(name).concat(Serialize.tryToJSONString(ftDisplay.name)!).concat(", ") .concat(symbol).concat(Serialize.tryToJSONString(ftDisplay.symbol)!).concat(", ") .concat(description).concat(Serialize.tryToJSONString(ftDisplay.description)!).concat(", ") .concat(externalLink).concat(Serialize.tryToJSONString(ftDisplay.externalURL.url)!) .concat("}") } /// Derives a symbol for use as an ERC20 or ERC721 symbol from a given string, presumably a Cadence contract name. /// Derivation is a process of slicing the first 4 characters of the string and converting them to uppercase. /// /// @param fromString: The string from which to derive a symbol /// /// @returns: A derived symbol for use as an ERC20 or ERC721 symbol based on the provided string, presumably a /// Cadence contract name /// access(all) view fun deriveSymbol(fromString: String): String { let defaultLen = 4 let len = fromString.length < defaultLen ? fromString.length : defaultLen return self.toUpperAlphaNumerical(fromString, upTo: len) } /// Returns the uppercase alphanumeric version of a given string. If upTo is nil or exceeds the length of the string, /// the entire string is converted to uppercase. /// /// @param str: The string to convert to uppercase /// @param upTo: The maximum number of characters to convert to uppercase /// /// @returns: The uppercase version of the given string /// access(all) view fun toUpperAlphaNumerical(_ str: String, upTo: Int?): String { let len = upTo ?? str.length var upper: String = "" for char in str { if upper.length == len { break } let bytes = char.utf8 if bytes.length != 1 { continue } let byte = bytes[0] if byte >= 97 && byte <= 122 { // Convert lower case to upper case let upperChar = String.fromUTF8([byte - UInt8(32)])! upper = upper.concat(upperChar) } else if byte >= 65 && byte <= 90 { // Keep upper case upper = upper.concat(char.toString()) } else if byte >= 48 && byte <= 57 { // Keep numbers upper = upper.concat(String.fromCharacters([char])) } else { // Skip non-alphanumeric characters continue } } return upper } }