Links, paths, and anchors #453
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src/pages/build/identifiers.md
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| use hdk::prelude::*; | ||
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| let my_first_id = agent_info()?.agent_initial_pubkey; | ||
| let my_current_id = agent_info()?.agent_latest_pubkey; |
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😬 makes me want to delete agent_latest_pubkey from holochain until its actually used and deepkey is stable, since its effectively a placeholder right now.
I might just not mention it here.
| let author_id = action.author(); | ||
| ``` | ||
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| ### External reference |
| use hdi::prelude::*; | ||
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| #[hdk_entry_helper] | ||
| pub struct MovieLoan { |
src/pages/build/identifiers.md
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| pub struct MovieLoan { | ||
| movie_hash: EntryHash, | ||
| lent_to: AgentPubKey, | ||
| loan_terms: ActionHash, |
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might make this field loan_duration or return_date timestamp so we don't need a LoanTerm entry that isn't actually created in any other snippets (and the reader isn't confused about why loan_terms is an action hash when there is no LoanTerm entry type)
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okay, that's fine -- I wanted to show a struct that had a mixture of different kinds of hashes, but EntryHash and AgentPubKey is prob enough rather than implying the existence of (or defining) a LoanTerms type.
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| * You may safely use the hash of an action you've just written as data in another action in the same function (e.g., in a link or an entry that contains the hash in a field), as long as you're not using relaxed chain top ordering. | ||
| * The same is also true of action hashes in your function's return value. | ||
| * Don't communicate the action hash with the front end, another cell, or another peer on the network via a remote function call or [signal](/concepts/9_signals/) _from within the same function that writes it_, in case the write fails. Instead, do your communicating in a follow-up step. The easiest way to do this is by implementing [a callback called `post_commit`](https://docs.rs/hdk/latest/hdk/#internal-callbacks) which receives a vector of all the actions that the function wrote. |
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wow amazing gotcha I've never run into this and never thought of it.
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super handy function -- scaffolded zomes use this trick as a way of updating front-end state on self-authored data.
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| ### Paths | ||
| When you want to create more complex collections, you'll need to use the paths library directly. |
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| When you want to create more complex collections, you'll need to use the paths library directly. | |
| When you want to create more complex collections, you'll want to use the paths library directly. |
| * [**Private**](/build/entries/#configure-an-entry-type), stored on the author's device in their source chain and accessible to them only, or | ||
| * **Public**, stored in the graph database and accessible to all participants. | ||
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| All actions are public. |
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Might be worth a sentence that peers store data locally in sqlite database with encryption enabled by default, but this can be disabled by compiling holochain without sqlite_encrypted (or maybe that's overkill and ignore me)
Co-authored-by: mattyg <[email protected]>
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@mattyg thanks so much for all the encouragement -- glad to hear it's landing 🙏🏼 I've been out of programming for so long that positive feedback is very welcome. And I think I'm getting the hang of writing Rust code (and hApp code), although there are some gnarly things along the way (e.g., holochain/holochain#4575 ). I've tried compiling all the code samples and discovered that there were a fair few errors; would you be willing to re-review this PR and make sure my 'solutions' to the errors are all reasonably idiomatic? |
| imdb_id: Some("tt0060196"), | ||
| release_date: Timestamp::from(Date::Utc("1966-12-23")), | ||
| imdb_id: Some("tt0060196".to_string()), | ||
| release_date: Timestamp(-95_472_000_000_000), // 1966-12-23 |
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I'd prefer to construct the timestamp from a human readable date. It looks like we can do so via chrono::DateTime<Utc> https://docs.rs/hdk/latest/hdk/prelude/struct.Timestamp.html#impl-From%3C%26DateTime%3CUtc%3E%3E-for-Timestamp
| title: "The Good, the Bad, and the Ugly".to_string(), | ||
| director_hash: EntryHash::from_raw_36(vec![ /* hash of 'Sergio Leone' entry */ ]), | ||
| imdb_id: Some("tt0060196".to_string()), | ||
| release_date: Timestamp(-95_472_000_000_000), |
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Same comment as above about constructing the timestamp
| None | ||
| let links_to_movies_starting_with_g = get_links( | ||
| // A path doesn't need to have a type in order to compute its hash. | ||
| GetLinksBuilder::try_new(path_to_movies_starting_with_g.path_entry_hash()?, LinkTypes::MovieByFirstLetter)? |
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| GetLinksBuilder::try_new(path_to_movies_starting_with_g.path_entry_hash()?, LinkTypes::MovieByFirstLetter)? | |
| GetLinksInputBuilder::try_new( | |
| path_to_movies_starting_with_g.path_entry_hash()?, | |
| LinkTypes::MovieByFirstLetter | |
| )? |
| ); | ||
| GetLinksInputBuilder::try_new(director_entry_hash, LinkTypes::DirectorToMovie)? | ||
| .get_options(GetStrategy::Network) | ||
| ..tag_prefix("year:196".as_bytes().to_owned().into()) |
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| ..tag_prefix("year:196".as_bytes().to_owned().into()) | |
| .tag_prefix("year:196".as_bytes().to_owned().into()) |
| use movie_integrity::*; | ||
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| let path_to_movies_starting_with_g = Path::from("movies_by_first_letter.g"); | ||
| let links_to_movies_starting_with_g = get_links( |
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| let links_to_movies_starting_with_g = get_links( |
| // A path doesn't need to have a type in order to compute its hash. | ||
| GetLinksBuilder::try_new(path_to_movies_starting_with_g.path_entry_hash()?, LinkTypes::MovieByFirstLetter)? | ||
| )?; | ||
| )?; |
Resolves #467
Seeking review for: