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use crate::prelude::*;
/// General function that can create any entry type.
///
/// This is used under the hood by [ `create_entry` ], [ `create_cap_grant` ] and [ `create_cap_claim` ].
///
/// The host builds a [ `Create` ] header for the passed entry value and commits a new element to the
/// chain.
///
/// Usually you don't need to use this function directly; it is the most general way to create an
/// entry and standardises the internals of higher level create functions.
pub fn create(create_input: CreateInput) -> ExternResult<HeaderHash> {
HDK.with(|h| h.borrow().create(create_input))
}
/// Update any entry type.
///
/// This is used under the hood by [ `update_entry` ], [ `update_cap_grant` ] and `update_cap_claim`.
/// @todo implement update_cap_claim
///
/// The host builds an [ `Update` ] header for the passed entry value and commits a new update to the
/// chain.
///
/// Usually you don't need to use this function directly; it is the most general way to update an
/// entry and standardises the internals of higher level create functions.
pub fn update(hash: HeaderHash, create_input: CreateInput) -> ExternResult<HeaderHash> {
HDK.with(|h| h.borrow().update(UpdateInput::new(hash, create_input)))
}
/// General function that can delete any entry type.
///
/// This is used under the hood by [ `delete_entry` ], [ `delete_cap_grant` ] and `delete_cap_claim`.
/// @todo implement delete_cap_claim
///
/// The host builds a [ `Delete` ] header for the passed entry and commits a new element to the chain.
///
/// Usually you don't need to use this function directly; it is the most general way to update an
/// entry and standardises the internals of higher level create functions.
pub fn delete(deletes_header_address: HeaderHash) -> ExternResult<HeaderHash> {
HDK.with(|h| {
h.borrow().delete(DeleteInput::new(
deletes_header_address,
ChainTopOrdering::default(),
))
})
}
/// Create an app entry.
///
/// Apps define app entries by registering entry def ids with the `entry_defs` callback and serialize the
/// entry content when committing to the source chain.
///
/// This function accepts any input that implements [ `TryInto<CreateInput>` ].
/// The default impls from the `#[hdk_entry( .. )]` and [ `entry_def!` ] macros include this.
///
/// With generic type handling it may make sense to directly construct [ `CreateInput` ] and [ `create` ].
///
/// e.g.
/// ```ignore
/// #[hdk_entry(id = "foo")]
/// pub struct Foo(u32);
/// create_entry(Foo(50))?;
/// ```
///
/// See [ `get` ] and [ `get_details` ] for more information on CRUD.
pub fn create_entry<I, E>(input: I) -> ExternResult<HeaderHash>
where
CreateInput: TryFrom<I, Error = E>,
WasmError: From<E>,
{
create(CreateInput::try_from(input)?)
}
/// Alias to delete
///
/// Takes the [ `HeaderHash` ] of the element to delete.
///
/// ```ignore
/// delete_entry(entry_hash(foo_entry)?)?;
/// ```
pub fn delete_entry(hash: HeaderHash) -> ExternResult<HeaderHash> {
delete(hash)
}
/// Hash anything that that implements [ `TryInto<Entry>` ].
///
/// Hashes are typed in holochain, e.g. [ `HeaderHash` ] and [ `EntryHash` ] are different and yield different
/// bytes for a given value. This ensures correctness and allows type based dispatch in various
/// areas of the codebase.
///
/// Usually you want to hash a value that you want to reference on the DHT with [ `get` ] etc. because
/// it represents some domain-specific data sourced externally or generated within the wasm.
/// [ `HeaderHash` ] hashes are _always_ generated by the process of committing something to a local
/// chain. Every host function that commits an entry returns the new [ `HeaderHash` ]. The [ `HeaderHash` ] can
/// also be used with [ `get` ] etc. to retreive a _specific_ element from the DHT rather than the
/// oldest live element.
/// However there is no way to _generate_ a header hash directly from a header from inside wasm.
/// [ `Element` ] values (entry+header pairs returned by [ `get` ] etc.) contain prehashed header structs
/// called [ `HeaderHashed` ], which is composed of a [ `HeaderHash` ] alongside the "raw" [ `Header` ] value. Generally the pre-hashing is
/// more efficient than hashing headers ad-hoc as hashing always needs to be done at the database
/// layer, so we want to re-use that as much as possible.
/// The header hash can be extracted from the Element as `element.header_hashed().as_hash()`.
/// @todo is there any use-case that can't be satisfied by the `header_hashed` approach?
///
/// Anything that is annotated with #[hdk_entry( .. )] or entry_def!( .. ) implements this so is
/// compatible automatically.
///
/// [ `hash_entry` ] is "dumb" in that it doesn't check that the entry is defined, committed, on the DHT or
/// any other validation, it simply generates the hash for the serialized representation of
/// something in the same way that the DHT would.
///
/// It is strongly recommended that you use the [ `hash_entry` ] function to calculate hashes to avoid
/// inconsistencies between hashes in the wasm guest and the host.
/// For example, a lot of the crypto crates in rust compile to wasm so in theory could generate the
/// hash in the guest, but there is the potential that the serialization logic could be slightly
/// different, etc.
///
/// ```ignore
/// #[hdk_entry(id="foo")]
/// struct Foo;
///
/// let foo_hash = hash_entry(Foo)?;
/// ```
pub fn hash_entry<I, E>(input: I) -> ExternResult<EntryHash>
where
Entry: TryFrom<I, Error = E>,
WasmError: From<E>,
{
HDK.with(|h| h.borrow().hash_entry(Entry::try_from(input)?))
}
/// Thin wrapper around update for app entries.
/// The hash is the [ `HeaderHash` ] of the deleted element, the input is a [ `TryInto<CreateInput>` ].
///
/// Updates can reference Elements which contain Entry data -- namely, Creates and other Updates -- but
/// not Deletes or system Elements
///
/// As updates can reference elements on other agent's source chains across unpredictable network
/// topologies, they are treated as a tree structure.
///
/// Many updates can point to a single create/update and continue to accumulate as long as agents
/// author them against that element. It is up to happ developers to decide how to ensure the tree
/// branches are walked appropriately and that updates point to the correct element, whatever that
/// means for the happ.
///
/// ```ignore
/// #[hdk_entry(id = "foo")]
/// struct Foo(u32);
///
/// let foo_zero_header_hash: HeaderHash = commit_entry!(Foo(0))?;
/// let foo_ten_update_header_hash: HeaderHash = update_entry(foo_zero_header_hash, Foo(10))?;
/// ```
///
/// @todo in the future this will be true because we will have the concept of 'redirects':
/// Works as an app entry delete+create.
///
/// See [ `create_entry` ]
/// See [ `update` ]
/// See [ `delete_entry` ]
pub fn update_entry<I, E>(hash: HeaderHash, input: I) -> ExternResult<HeaderHash>
where
CreateInput: TryFrom<I, Error = E>,
WasmError: From<E>,
{
update(hash, CreateInput::try_from(input)?)
}
/// Gets an element for a given entry or header hash.
///
/// The behaviour of get changes subtly per the _type of the passed hash_.
/// A header hash returns the element for that header, i.e. header+entry or header+None.
/// An entry hash returns the "oldest live" element, i.e. header+entry.
///
/// An element is no longer live once it is referenced by a valid delete element.
/// An update to an element does not change its liveness.
/// See [ `get_details` ] for more information about how CRUD elements reference each other.
///
/// Note: [ `get` ] __always triggers and blocks on a network call__.
/// @todo implement a 'get optimistic' that returns based on the current opinion of the world
/// and performs network calls in the background so they are available 'next time'.
///
/// Note: Deletes are considered in the liveness but Updates are not currently followed
/// automatically due to the need for the happ to disambiguate update logic.
/// @todo implement 'redirect' logic so that updates are followed by [ `get` ].
///
/// Note: Updates typically point to a different entry hash than what they are updating but not
/// always, e.g. consider changing `foo` to `bar` back to `foo`. The entry hashes in a crud
/// tree can be circular but the header hashes are never circular.
/// In this case, deleting the create for foo would make the second update pointing to foo
/// the "oldest live" element.
///
/// Note: "oldest live" only relates to disambiguating many creates and updates from many authors
/// pointing to a single entry, it is not the "current value" of an entry in a CRUD sense.
/// e.g. If "foo" is created then updated to "bar", a [ `get` ] on the hash of "foo" will return
/// "foo" as part of an element with the "oldest live" header.
/// To discover "bar" the agent needs to call `get_details` and decide how it wants to
/// collapse many potential creates, updates and deletes down into a single or filtered
/// set of updates, to "walk the tree".
/// e.g. Updates could include a proof of work and a tree would collapse to a simple
/// blockchain if the agent follows the "heaviest chain".
/// e.g. Updates could represent turns in a 2-player game and the update with the newest
/// timestamp countersigned by both players represents an opt-in chain of updates with
/// support for casual "undo" with player's consent.
/// e.g. Domain/user names could be claimed on a "first come, first serve" basis with only
/// creates and deletes allowed by validation rules, the "oldest live" element _does_
/// represent the element pointing at the first agent to claim a name, but it could also
/// be checked manually by the app with `get_details`.
///
/// Note: "oldest live" is only as good as the information available to the authorities the agent
/// contacts on their current network partition, there could always be an older live entry
/// on another partition, and of course the oldest live entry could be deleted and no longer
/// be live.
pub fn get<H>(hash: H, options: GetOptions) -> ExternResult<Option<Element>>
where
AnyDhtHash: From<H>,
{
Ok(HDK
.with(|h| {
h.borrow()
.get(vec![GetInput::new(AnyDhtHash::from(hash), options)])
})?
.into_iter()
.next()
.unwrap())
}
/// MUST get an EntryHashed at a given EntryHash.
///
/// The EntryHashed is NOT guaranteed to be associated with a valid (or even validated) Header/Element.
/// For example, an invalid Element could be published and `must_get_entry` would return the EntryHashed.
///
/// This may be useful during validation callbacks where the validity and relevance of some content can be
/// asserted by the CURRENT validation callback independent of an Element. This behaviour avoids the potential for
/// eclipse attacks to lie about the validity of some data and cause problems for a hApp.
/// If you NEED to know that a dependency is valid in order for the current validation logic
/// (e.g. inductive validation of a tree) then `must_get_valid_element` is likely what you need.
///
/// `must_get_entry` is available in contexts such as validation where both determinism and network access is desirable.
///
/// An EntryHashed will NOT be returned if:
/// - @TODO It is PURGED (community redacted entry)
/// - @TODO ALL headers pointing to it are WITHDRAWN by the authors
/// - ALL headers pointing to it are ABANDONED by ALL authorities due to validation failure
/// - Nobody knows about it on the currently visible network
///
/// If an EntryHashed fails to be returned:
///
/// - Callbacks will return early with `UnresolvedDependencies`
/// - Zome calls will receive a `WasmError` from the host
pub fn must_get_entry(entry_hash: EntryHash) -> ExternResult<EntryHashed> {
HDK.with(|h| {
h.borrow()
.must_get_entry(MustGetEntryInput::new(entry_hash))
})
}
/// MUST get a SignedHeaderHashed at a given HeaderHash.
///
/// The SignedHeaderHashed is NOT guaranteed to be a valid (or even validated) Element.
/// For example, an invalid Header could be published and `must_get_header` would return the `SignedHeaderHashed`.
///
/// This may be useful during validation callbacks where the validity depends on a Header existing regardless of its associated Entry.
/// For example, we may simply need to check that the author is the same for two referenced Headers.
///
/// `must_get_header` is available in contexts such as validation where both determinism and network access is desirable.
///
/// A `SignedHeaderHashed` will NOT be returned if:
///
/// - @TODO The header is WITHDRAWN by the author
/// - @TODO The header is ABANDONED by ALL authorities
/// - Nobody knows about it on the currently visible network
///
/// If a `SignedHeaderHashed` fails to be returned:
///
/// - Callbacks will return early with `UnresolvedDependencies`
/// - Zome calls will receive a `WasmError` from the host
pub fn must_get_header(header_hash: HeaderHash) -> ExternResult<SignedHeaderHashed> {
HDK.with(|h| {
h.borrow()
.must_get_header(MustGetHeaderInput::new(header_hash))
})
}
/// MUST get a VALID Element at a given HeaderHash
///
/// The Element is guaranteed to be valid.
/// More accurately the Element is guarantee to be consistently reported as valid by the visible network.
///
/// The validity requirement makes this more complex but notably enables inductive validation of arbitrary graph structures.
/// For example "If this Element is valid, and its parent is valid, up to the root, then the whole tree of Elements is valid".
///
/// If at least one authority (1 of N trust) claims the Element is invalid then a conflict resolution/warranting round will be triggered.
///
/// In the case of a total eclipse (every visible authority is lying) then we cannot immediately detect an invalid Element.
/// Unlike `must_get_entry` and `must_get_header` we cannot simply inspect the cryptographic integrity to know this.
///
/// In theory we can run validation of the returned Element ourselves, which itself may be based on `must_get_X` calls.
/// If there is a large nested graph of `must_get_valid_element` calls this could be extremely heavy.
/// Note though that each "hop" in recursive validation is routed to a completely different set of authorities.
/// It does not take many hops to reach the point where an attacker needs to eclipse the entire network to lie about Element validity.
///
/// @TODO We keep signed receipts from authorities serving up "valid elements".
/// - If we ever discover an element we were told is valid is invalid we can retroactively look to warrant authorities
/// - We can async (e.g. in a background task) be recursively validating Element dependencies ourselves, following hops until there is no room for lies
/// - We can with small probability recursively validate to several hops inline to discourage potential eclipse attacks with a credible immediate threat
///
/// If you do not care about validity and simply want a pair of Header+Entry data, then use both `must_get_header` and `must_get_entry` together.
///
/// `must_get_valid_element` is available in contexts such as validation where both determinism and network access is desirable.
///
/// An `Element` will not be returned if:
///
/// - @TODO It is WITHDRAWN by the author
/// - @TODO The Entry is PURGED by the community
/// - It is ABANDONED by ALL authorities due to failed validation
/// - If ANY authority (1 of N trust) OR ourselves (0 of N trust) believes it INVALID
/// - Nobody knows about it on the visible network
///
/// If an `Element` fails to be returned:
///
/// - Callbacks will return early with `UnresolvedDependencies`
/// - Zome calls will receive a `WasmError` from the host
pub fn must_get_valid_element(header_hash: HeaderHash) -> ExternResult<Element> {
HDK.with(|h| {
h.borrow()
.must_get_valid_element(MustGetValidElementInput::new(header_hash))
})
}
/// Get an element from the hash AND the details for the entry or header hash passed in.
/// Returns [ `None` ] if the entry/header does not exist.
/// The details returned are a contextual mix of elements and header hashes, see below.
///
/// Note: The return details will be inferred by the hash type passed in, be careful to pass in the
/// correct hash type for the details you want.
///
/// Note: If a header hash is passed in the element returned is the specified element.
/// If an entry hash is passed in all the headers (so implicitly all the elements) are
/// returned for the entry that matches that hash.
/// See [ `get` ] for more information about what "oldest live" means.
///
/// The details returned include relevant creates, updates and deletes for the hash passed in.
///
/// Creates are initial header/entry combinations (elements) produced by commit_entry! and cannot
/// reference other headers.
/// Updates and deletes both reference a specific header+entry combination.
/// Updates must reference another create or update header+entry.
/// Deletes must reference a create or update header+entry (nothing can reference a delete).
///
/// Full elements are returned for direct references to the passed hash.
/// Header hashes are returned for references to references to the passed hash.
///
/// [ `Details` ] for a header hash return:
/// - the element for this header hash if it exists
/// - all update and delete _elements_ that reference that specified header
///
/// [ `Details` ] for an entry hash return:
/// - all creates, updates and delete _elements_ that reference that entry hash
/// - all update and delete _elements_ that reference the elements that reference the entry hash
///
/// Note: Entries are just values, so can be referenced by many CRUD headers by many authors.
/// e.g. the number 1 or string "foo" can be referenced by anyone publishing CRUD headers at
/// any time they need to represent 1 or "foo" for a create, update or delete.
/// If you need to disambiguate entry values, provide uniqueness in the entry value such as
/// a unique hash (e.g. current chain head), timestamp (careful about collisions!), or random
/// bytes/uuid (see random_bytes() and the uuid rust crate that supports uuids from bytes).
///
/// Note: There are multiple header types that exist and operate entirely outside of CRUD elements
/// so they cannot reference or be referenced by CRUD, so are immutable or have their own
/// mutation logic (e.g. link create/delete) and will not be included in [ `get_details` ] results
/// e.g. the DNA itself, links, migrations, etc.
/// However the element will still be returned by [ `get_details` ] if a header hash is passed,
/// these header-only elements will have [ `None` ] as the entry value.
pub fn get_details<H: Into<AnyDhtHash>>(
hash: H,
options: GetOptions,
) -> ExternResult<Option<Details>> {
Ok(HDK
.with(|h| {
h.borrow()
.get_details(vec![GetInput::new(hash.into(), options)])
})?
.into_iter()
.next()
.unwrap())
}
/// Trait for binding static [ `EntryDef` ] property access for a type.
/// See [ `register_entry` ]
pub trait EntryDefRegistration {
fn entry_def() -> crate::prelude::EntryDef;
fn entry_def_id() -> crate::prelude::EntryDefId;
fn entry_visibility() -> crate::prelude::EntryVisibility;
fn crdt_type() -> crate::prelude::CrdtType;
fn required_validations() -> crate::prelude::RequiredValidations;
}
/// Implements conversion traits to allow a struct to be handled as an app entry.
/// If you have some need to implement custom serialization logic or metadata injection
/// you can do so by implementing these traits manually instead.
///
/// This requires that TryFrom and TryInto [ `derive@SerializedBytes` ] is implemented for the entry type,
/// which implies that [ `serde::Serialize` ] and [ `serde::Deserialize` ] is also implemented.
/// These can all be derived and there is an attribute macro that both does the default defines.
#[macro_export]
macro_rules! app_entry {
( $t:ident ) => {
impl TryFrom<&$crate::prelude::Entry> for $t {
type Error = $crate::prelude::WasmError;
fn try_from(entry: &$crate::prelude::Entry) -> Result<Self, Self::Error> {
match entry {
$crate::prelude::Entry::App(eb) => Ok(Self::try_from(
$crate::prelude::SerializedBytes::from(eb.to_owned()),
)?),
$crate::prelude::Entry::CounterSign(_, eb) => Ok(Self::try_from(
$crate::prelude::SerializedBytes::from(eb.to_owned()),
)?),
_ => Err($crate::prelude::SerializedBytesError::Deserialize(format!(
"{:?} is not an Entry::App or Entry::CounterSign so has no serialized bytes",
entry
))
.into()),
}
}
}
impl TryFrom<$crate::prelude::Entry> for $t {
type Error = $crate::prelude::WasmError;
fn try_from(entry: $crate::prelude::Entry) -> Result<Self, Self::Error> {
Self::try_from(&entry)
}
}
impl TryFrom<$crate::prelude::EntryHashed> for $t {
type Error = $crate::prelude::WasmError;
fn try_from(entry_hashed: $crate::prelude::EntryHashed) -> Result<Self, Self::Error> {
Self::try_from(entry_hashed.as_content())
}
}
impl TryFrom<&$crate::prelude::Element> for $t {
type Error = $crate::prelude::WasmError;
fn try_from(element: &$crate::prelude::Element) -> Result<Self, Self::Error> {
Ok(match element.entry() {
ElementEntry::Present(entry) => Self::try_from(entry)?,
_ => return Err(Self::Error::Guest(format!("Tried to deserialize an element, expecting it to contain entry data, but there was none. Element HeaderHash: {}", element.header_hashed().as_hash()))),
})
}
}
impl TryFrom<$crate::prelude::Element> for $t {
type Error = $crate::prelude::WasmError;
fn try_from(element: $crate::prelude::Element) -> Result<Self, Self::Error> {
(&element).try_into()
}
}
impl TryFrom<&$t> for $crate::prelude::AppEntryBytes {
type Error = $crate::prelude::WasmError;
fn try_from(t: &$t) -> Result<Self, Self::Error> {
AppEntryBytes::try_from(SerializedBytes::try_from(t)?).map_err(|entry_error| match entry_error {
EntryError::SerializedBytes(serialized_bytes_error) => {
WasmError::Serialize(serialized_bytes_error)
}
EntryError::EntryTooLarge(_) => {
WasmError::Guest(entry_error.to_string())
}
})
}
}
impl TryFrom<$t> for $crate::prelude::AppEntryBytes {
type Error = $crate::prelude::WasmError;
fn try_from(t: $t) -> Result<Self, Self::Error> {
Self::try_from(&t)
}
}
impl TryFrom<&$t> for $crate::prelude::Entry {
type Error = $crate::prelude::WasmError;
fn try_from(t: &$t) -> Result<Self, Self::Error> {
Ok(Self::App($crate::prelude::AppEntryBytes::try_from(t)?))
}
}
impl TryFrom<$t> for $crate::prelude::Entry {
type Error = $crate::prelude::WasmError;
fn try_from(t: $t) -> Result<Self, Self::Error> {
Self::try_from(&t)
}
}
};
}
/// Implements a whole lot of sane defaults for a struct or enum that should behave as an entry,
/// *without* implementing the app entry conversion interface.
///
/// This allows crates to easily define a struct as an entry separately to binding that struct
/// as an entry type in a dependent crate.
///
/// For most normal applications, you should use the [ `entry_def!` ] macro instead.
#[macro_export]
macro_rules! register_entry {
( $t:ident $def:expr ) => {
impl $crate::prelude::EntryDefRegistration for $t {
fn entry_def() -> $crate::prelude::EntryDef {
$def
}
fn entry_def_id() -> $crate::prelude::EntryDefId {
Self::entry_def().id
}
fn entry_visibility() -> $crate::prelude::EntryVisibility {
Self::entry_def().visibility
}
fn crdt_type() -> $crate::prelude::CrdtType {
Self::entry_def().crdt_type
}
fn required_validations() -> $crate::prelude::RequiredValidations {
Self::entry_def().required_validations
}
}
impl From<$t> for $crate::prelude::EntryDef
where
$t: $crate::prelude::EntryDefRegistration,
{
fn from(_: $t) -> Self {
$t::entry_def()
}
}
impl From<&$t> for $crate::prelude::EntryDef
where
$t: $crate::prelude::EntryDefRegistration,
{
fn from(_: &$t) -> Self {
$t::entry_def()
}
}
impl From<$t> for $crate::prelude::EntryDefId
where
$t: $crate::prelude::EntryDefRegistration,
{
fn from(_: $t) -> Self {
$t::entry_def_id()
}
}
impl From<&$t> for $crate::prelude::EntryDefId
where
$t: $crate::prelude::EntryDefRegistration,
{
fn from(_: &$t) -> Self {
$t::entry_def_id()
}
}
impl TryFrom<&$t> for $crate::prelude::CreateInput
where
$t: $crate::prelude::EntryDefRegistration,
{
type Error = $crate::prelude::WasmError;
fn try_from(t: &$t) -> Result<Self, Self::Error> {
Ok(Self::new(
$t::entry_def_id(),
t.try_into()?,
ChainTopOrdering::default(),
))
}
}
impl TryFrom<$t> for $crate::prelude::CreateInput {
type Error = $crate::prelude::WasmError;
fn try_from(t: $t) -> Result<Self, Self::Error> {
(&t).try_into()
}
}
impl From<$t> for $crate::prelude::EntryVisibility
where
$t: $crate::prelude::EntryDefRegistration,
{
fn from(_: $t) -> Self {
$t::entry_visibility()
}
}
impl From<&$t> for $crate::prelude::EntryVisibility
where
$t: $crate::prelude::EntryDefRegistration,
{
fn from(_: &$t) -> Self {
$t::entry_visibility()
}
}
impl From<$t> for $crate::prelude::CrdtType
where
$t: $crate::prelude::EntryDefRegistration,
{
fn from(_: $t) -> Self {
$t::crdt_type()
}
}
impl From<&$t> for $crate::prelude::CrdtType
where
$t: $crate::prelude::EntryDefRegistration,
{
fn from(_: &$t) -> Self {
$t::crdt_type()
}
}
impl From<$t> for $crate::prelude::RequiredValidations
where
$t: $crate::prelude::EntryDefRegistration,
{
fn from(_: $t) -> Self {
$t::required_validations()
}
}
impl From<&$t> for $crate::prelude::RequiredValidations
where
$t: $crate::prelude::EntryDefRegistration,
{
fn from(_: &$t) -> Self {
$t::required_validations()
}
}
};
}
/// Implements a whole lot of sane defaults for a struct or enum that should behave as an entry.
/// All the entry def fields are available as dedicated methods on the type and matching From impls
/// are provided for each. This allows for both Foo::entry_def() and EntryDef::from(Foo::new())
/// style logic which are both useful in different scenarios.
///
/// For example, the Foo::entry_def() style works best in the entry_defs callback as it doesn't
/// require an instantiated Foo in order to get the definition.
/// On the other hand, EntryDef::from(Foo::new()) works better when e.g. using create_entry() as
/// an instance of Foo already exists and we need the entry def id back for creates and updates.
///
/// If you don't want to use the macro you can simply implement similar fns youself.
///
/// This is not a trait at the moment, it could be in the future but for now these functions and
/// impls are just a loose set of conventions.
///
/// It's actually entirely possible to interact with core directly without any of these.
/// e.g. [ `create_entry` ] is just building a tuple of [ `EntryDefId` ] and [ `Entry::App` ] under the hood.
///
/// This requires that TryFrom and TryInto [ `derive@SerializedBytes` ] is implemented for the entry type,
/// which implies that [ `serde::Serialize` ] and [ `serde::Deserialize` ] is also implemented.
/// These can all be derived and there is an attribute macro that both does the default defines.
///
/// e.g. the following are equivalent
///
/// ```ignore
/// #[hdk_entry(id = "foo", visibility = "private", required_validations = 6, )]
/// pub struct Foo;
/// ```
///
/// ```ignore
/// #[derive(SerializedBytes, serde::Serialize, serde::Deserialize)]
/// pub struct Foo;
/// entry_def!(Foo EntryDef {
/// id: "foo".into(),
/// visibility: EntryVisibility::Private,
/// ..Default::default()
/// });
/// ```
#[macro_export]
macro_rules! entry_def {
( $t:ident $def:expr ) => {
app_entry!($t);
register_entry!($t $def);
};
}
/// Shorthand to implement the entry defs callback similar to the vec![ .. ] macro but for entries.
///
/// e.g. the following are the same
///
/// ```ignore
/// entry_defs![ Foo::entry_def() ];
/// ```
///
/// ```ignore
/// #[hdk_extern]
/// fn entry_defs(_: ()) -> ExternResult<EntryDefsCallbackResult> {
/// Ok(vec![ Foo::entry_def() ].into())
/// }
/// ```
#[macro_export]
macro_rules! entry_defs {
[ $( $def:expr ),* ] => {
#[hdk_extern]
pub fn entry_defs(_: ()) -> $crate::prelude::ExternResult<$crate::prelude::EntryDefsCallbackResult> {
Ok($crate::prelude::EntryDefsCallbackResult::from(vec![ $( $def ),* ]))
}
};
}
/// Attempts to lookup the [ `EntryDefIndex` ] given an [ `EntryDefId` ].
///
/// The [ `EntryDefId` ] is a [ `String` ] newtype and the [ `EntryDefIndex` ] is a u8 newtype.
/// The [ `EntryDefIndex` ] is used to reference the entry type in headers on the DHT and as the index of the type exported to tooling.
/// The [ `EntryDefId` ] is the 'human friendly' string that the [ `entry_defs!` ] callback maps to the index.
///
/// The host actually has no idea how to do this mapping, it is provided by the wasm!
///
/// Therefore this is a macro that calls the [ `entry_defs!` ] callback as defined within a zome directly from the zome.
/// It is a macro so that we can call a function with a known name `crate::entry_defs` from the HDK before the function is defined.
///
/// Obviously this assumes and requires that a compliant [ `entry_defs!` ] callback _is_ defined at the root of the crate.
#[macro_export]
macro_rules! entry_def_index {
( $t:ty ) => {
match $crate::prelude::zome_info() {
Ok(ZomeInfo { entry_defs, .. }) => {
match entry_defs.entry_def_index_from_id(<$t>::entry_def_id()) {
Some(entry_def_index) => Ok::<
$crate::prelude::EntryDefIndex,
$crate::prelude::WasmError,
>(entry_def_index),
None => {
$crate::prelude::tracing::error!(
entry_def_type = stringify!($t),
?entry_defs,
"Failed to lookup index for entry def id."
);
Err::<$crate::prelude::EntryDefIndex, $crate::prelude::WasmError>(
$crate::prelude::WasmError::Guest(
"Failed to lookup index for entry def id.".into(),
),
)
}
}
}
Err(error) => {
$crate::prelude::tracing::error!(?error, "Failed to lookup entry defs.");
Err::<$crate::prelude::EntryDefIndex, $crate::prelude::WasmError>(error)
}
}
};
}
#[macro_export]
macro_rules! entry_type {
( $t:ty ) => {
match $crate::prelude::entry_def_index!($t) {
Ok(e_id) => match $crate::prelude::zome_info() {
Ok(ZomeInfo { id, .. }) => Ok($crate::prelude::EntryType::App(
$crate::prelude::AppEntryType::new(e_id, id, <$t>::entry_visibility()),
)),
Err(e) => Err(e),
_ => unreachable!(),
},
Err(e) => Err(e),
}
};
}