forked from cerc-io/ipld-eth-server
27 lines
1012 B
Markdown
27 lines
1012 B
Markdown
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# Handlers
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## Description
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Handlers must be defined in order to define what events should trigger data updates and how those are performed.
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## Interface
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### Initializer
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Accepts DB and Blockchain from Vulcanize and returns a new handler. E.g. for a new object "Cup":
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`func NewCupHandler(db *postgres.DB, blockchain core.ContractDataFetcher) handlers.Handler`
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### Execute
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Triggers operations to take in response to a given log event.
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Can persist data from logs, fetch and persist arbitrary data from outside services (e.g. contract state), or take any number of other actions. E.g.:
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`func (cupHandler *CupHandler) Execute() error`
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## Additional Requirements
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Handlers must define log filters and create them so that relevant watched events can be identified and retrieved. E.g.:
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```$xslt
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{
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Name: "CupsBite",
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FromBlock: 0,
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ToBlock: -1,
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Address: "0x448a5065aebb8e423f0896e6c5d525c040f59af3",
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Topics: core.Topics{"0x40cc885400000000000000000000000000000000000000000000000000000000"},
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},
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```
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