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Queries

Although much of the information about the state of the blockchain can be obtained, as we've shown before, using an event subscriber and a filter to narrow the scope of the events to those of interest, sometimes you need to take a more direct approach. Enter queries.

Queries are small instruction-like objects that, when sent to an Iroha peer, prompt a response with details from the current world state view.

This is not necessarily the only kind of information that is available on the network, but it's the only kind of information that is guaranteed to be accessible on all networks.

For each deployment of Iroha, there might be other available information. For example, the availability of telemetry data is up to the network administrators. It's entirely their decision whether or not they want to allocate processing power to track the work instead of using it to do the actual work. By contrast, some functions are always required, e.g. having access to your account balance.

INFO

In the LTS version of Iroha 2, most queries can not sorted, but can be paginated and filtered. As such, some queries, which we'll mark with a warning sign, should be used with great care, and you should think about the pagination scheme for them.

The iroha2-dev version implements sorting that could be combined with pagination and filtering.

Conventions

In the following sections we shall try to mirror the module structure of the queries and present to you what they do.

Before we proceed, we should discuss a few conventions. We use the expressions gets, returns, searches with a precise meaning in the following (somewhat encyclopædic) section.

  • gets means that the query already has the data readily available and the data is trivial. Use these queries at will;
  • returns or finds mean that the query has the data readily available, just as with gets, but the data is not trivial. You can still use these queries, but be mindful of the performance impact;
  • searches differs from the above two. Data must be actively collected and neither the return type nor the collection process is cheap. Use with great care.

Another convention that we follow is that the queries are provided with just one data type as input, and parameterised by the type of the output. We should take some time to explain how to interpret the data.

How to read FindZByXAndY queries

The queries will have a Parameters and a Returns section. The parameters can either be single or multiple types, while the output is almost always either one type, or a Vec<Type> kind of construction.

Parameters

When we say

Parameters: (X, Y)

we mean that in Rust source code you need to construct the query as follows:

rust
let query = FindZByXAndY::new(x: X, y: Y);

where x and y are variables of type X and Y respectively.

We'll provide you with information about each type, otherwise, refer to the guide for each programming language for more information.

Returns

When we say

Returns: Vec<Z>

we mean that the return value is a collection of more than one element of type Z. Depending on the SDK implementation this can be a type native to the language (e.g. JavaScript) or a thin wrapper around the Rust Vec structure.

Pagination

For both a Vec<Z> and just Z as the return type, you can use client.request(query) to submit a query and get the full result in one go.

However, some queries, particularly the ones with "All" in their names, can return exorbitant amounts of data. As such, we highly recommend you consider pagination to reduce the load on the system.

To construct a Pagination, you need to call client.request_with_pagination(query, pagination), where the pagination is constructed as follows:

rust
let starting_result: u32 = _;
let limit: u32 = _;
let pagination = Pagination::new(Some(starting_result), Some(limit));

Filters

When you create a query, you can use a filter to only return the results that match the specified filter.

Sorting

The LTS version of Iroha 2 does not support sorting query results. However, in the latest (iroha2-dev) version of Iroha 2 we offer you the way to sort query results.

::: dev

Sorting only applies to entities that have metadata, as the metadata key is used to sort query results.

You can combine sorting with pagination and filters. Note that sorting is an optional feature, most queries with pagination won't need it.

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Create a query

Use QueryBox to construct a query. For example, a query to find all accounts would be created like this:

rust
let query = QueryBox::FindAllAccounts(FindAllAccounts {});

Here is an example of a query that finds Alice's assets:

rust
let alice_id =
    <Account as Identifiable>::Id::from_str("alice@wonderland")?;
let query = QueryBox::FindAssetsByAccountId(
    FindAssetsByAccountId::new(alice_id)
  );

Role

An optional feature. By default, it is present on all Iroha 2 deployments when they're compiled in the private blockchain configuration.

You can learn more about roles in a dedicated section.

FindAllRoles

  • Returns: Vec<Roles>

  • Details: Returns all roles registered as global (as opposed to domain-scoped) in the blockchain.

    WARNING

    This query returns a large volume of data.

FindAllRoleIds

  • Returns: Vec<Roles>

  • Details: Returns IDs of all the roles registered as global (as opposed to domain-scoped) in the blockchain.

    Note that it does not return its values, which contain permission tokens, only IDs.

FindRoleByRoleId

  • Parameters: RoleId

  • Returns: Vec<Roles>

  • Details: Returns the role that has the provided role ID.

    For example, given the name of the role admin, it will return all of the admin-level permission tokens.

FindRolesByAccountId

  • Parameters: AccountId

  • Returns: Vec<RoleId>

  • Details: Returns all of the role IDs that are attached to the given account.

    Note that unlike FindAllRoles, it does not return the roles themselves.

Permission

A semi-optional feature. You have permissions in both public and private blockchains but the use cases are different:

  • In a public blockchain, most accounts have the same common-sense permissions.
  • In a private blockchain, most accounts are assumed not to be able to do anything outside of their own account or domain unless explicitly granted said permission.

We talk about permissions in more detail in a dedicated chapter.

FindAllPermissionTokenDefinitions

::: dev

  • Returns: Vec<PermissionTokenDefinition>

  • Details: Finds all registered permission token definitions.

:::

FindPermissionTokensByAccountId

  • Parameters: AccountId

  • Returns: Vec<PermissionToken>

  • Details: Returns all of the permission tokens granted to the specified account.

Account

Most queries in Iroha pertain to accounts. At the moment this is the most diverse set of queries.

FindAllAccounts

  • Returns: Vec<Account>

  • Details: Finds all accounts registered globally in the blockchain.

    WARNING

    This query returns a large volume of data.

FindAccountById

  • Parameters: AccountId

  • Returns: Account

  • Details: Returns the full account information corresponding to the given AccountId.

FindAccountKeyValueByIdAndKey

  • Parameters: (AccountId, Name)

  • Returns: Value

  • Details: Returns the value keyed by the provided Name for the given account.

    This is done by querying the metadata attached to the given account.

FindAccountsByName

  • Parameters: Name

  • Returns: Vec<Account>

  • Details: Returns all of the accounts that have the given Name.

    This is particularly useful if you remember the name of the account, but do not, for example, recall the domain name in which it was registered.

FindAccountsByDomainId

  • Parameters: DomainId

  • Returns: Vec<Account>

  • Details: Returns all accounts that belong to a specific domain.

    Note that this returns the full accounts and not the AccountId collection.

    WARNING

    This query returns a large volume of data.

FindAccountsWithAsset

  • Parameters: AccountId

  • Returns: Vec<Account>

  • Details: Returns all accounts that have the given asset.

Asset

Assets include simple numbers, but also a special type of key-to-value map that is used as a secure data storage for privileged information.

FindAllAssets

  • Returns: Vec<Asset>

  • Details: Returns all known assets by value.

    WARNING

    This query returns a large volume of data.

    INFO

    You should note that this is not the same as AssetDefinition. If you have one asset called e.g. tea#wonderland that belongs to every account on the blockchain, you will receive the aggregated value across all accounts, but not the information such as the type of the asset.

FindAllAssetDefinitions

  • Returns: Vec<AssetDefinition>

  • Details: Returns all known asset definitions by value.

    WARNING

    This query returns a large volume of data.

    TIP

    To reduce the load on the network, we store the definition of an asset separate from its instances. So if you want to know if an asset is mintable or what type is stored in it, you need to query the asset definition, rather than the asset itself.

FindAssetById

  • Parameters: AssetId

  • Returns: Asset

  • Details: Returns the aggregated data about the asset usage across the network.

FindAssetsByName

  • Parameters: Name

  • Returns: Vec<Asset>

  • Details: Searches the network for all assets that match the given name.

FindAssetsByAccountId

  • Parameters: AccountId

  • Returns: Vec<Asset>

  • Details: Returns all of the assets that belong to a given account.

FindAssetsByAssetDefinitionId

  • Parameters: AssetDefinitionId

  • Returns: Vec<Asset>

  • Details: Searches for all of the assets that have the given definition ID.

WARNING

This query returns a large volume of data.

FindAssetsByDomainId

  • Parameters: DomainId

  • Returns: Vec<Asset>

  • Details: Returns all assets that are registered in the given domain.

WARNING

This query returns a large volume of data.

FindAssetsByDomainIdAndAssetDefinitionId

  • Parameters: (DomainId, AssetDefinitionId)

  • Returns: Vec<Asset>

  • Details: Searches the domain for assets that have the given definition ID.

FindAssetQuantityById

  • Parameters: AssetId

  • Returns: u32

  • Details: Returns the asset quantity.

    Note that this query assumes that the asset given by the identifier is of type AssetValue::Quantity.

    WARNING

    This query can fail.

FindAssetKeyValueByIdAndKey

  • Parameters: (AssetId, Name)

  • Returns: Value

  • Details: Gets the value keyed by the given name in the metadata of the asset corresponding to the given identifier.

FindAssetDefinitionKeyValueByIdAndKey

  • Parameters: (AssetDefinitionId, Name)

  • Returns: Value

  • Details: Gets the value keyed by the given name in the metadata of the asset definition corresponding to the given identifier.

Block

FindAllBlocks

  • Returns: Vec<Block>
  • Details: Returns all blocks in the blockchain.

FindAllBlockHeaders

::: dev

  • Returns: Vec<BlockHeader>
  • Details: Returns all block headers for blocks in the blockchain.

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FindBlockHeaderByHash

::: dev

  • Parameters: Hash
  • Returns: BlockHeader
  • Details: Gets the block header that matches the hash that was provided.

:::

Domain

The domain is the basic unit of organisation in an Iroha blockchain. Accounts and assets must be registered inside a domain, triggers are usually scoped by domain, and most queries have the domain as a possible input.

FindAllDomains

  • Returns: Vec<Domain>

  • Details: Returns all of the known registered domains.

    WARNING

    This query returns the full contents of the world state view as of execution. This query should be used sparingly and for debugging purposes only.

FindDomainById

  • Parameters: DomainId

  • Returns: Domain

  • Details: Gets the domain corresponding to the given identifier.

    WARNING

    This query returns a large volume of data.

FindDomainKeyValueByIdAndKey

  • Parameters: (DomainId, Name)

  • Returns: Value

  • Details: Returns the value keyed by the given name in the domain corresponding to the given identifier.

Peer

A peer is the basic unit of storage and validation. In common parlance we may conflate the node and the peer binary running on the node, but in this case we specifically mean the peer binary as a server with its specific configuration.

FindAllPeers

  • Returns: Vec<Peer>

  • Details: Returns all known peers identified by their key and accompanied by the address of the API endpoint of each.

FindAllParameters

  • Returns: Vec<Parameter>

    rust
    pub enum Parameter {
        /// Maximum amount of Faulty Peers in the system.
        MaximumFaultyPeersAmount(u32),
        /// Maximum time for a leader to create a block.
        BlockTime(u128),
        /// Maximum time for a proxy tail to send commit message.
        CommitTime(u128),
        /// Time to wait for a transaction Receipt.
        TransactionReceiptTime(u128),
    }
    
  • Details: Returns the parameters used by all peers in the network.

    This is useful for debugging if any of the peers are incorrectly configured and causing view changes.

Transaction

It is often necessary to query the state of specific transactions, especially for use in blockchain explorers and for user-facing applications.

FindTransactionsByAccountId

  • Parameters: AccountId

  • Returns: Vec<TransactionValue>

    rust
    pub enum TransactionValue {
        /// Committed transaction
        Transaction(Box<VersionedTransaction>),
        /// Rejected transaction with reason of rejection
        RejectedTransaction(Box<VersionedRejectedTransaction>),
    }
    
  • Details: Returns the full set of transactions that an account has submitted throughout the existence of the blockchain.

    WARNING

    This query returns a large volume of data.

FindTransactionByHash

  • Parameters: Hash

  • Returns: TransactionValue

  • Details: Returns the transaction by hash.

Trigger

Iroha is an event-driven architecture. Every modification of the world state emits a corresponding event that can be captured by appropriate event listeners called filters.

FindAllActiveTriggerIds

  • Returns: Vec<TriggerId>

  • Details: Finds all currently active triggers, that is, triggers that have not expired at the time of the query.

WARNING

This query returns a large volume of data.

FindTriggerById

  • Parameters: TriggerId

  • Returns: Trigger

  • Details: Finds the trigger with the given ID.

FindTriggerKeyValueByIdAndKey

  • Parameters: (TriggerId, Name)

  • Returns: Trigger

  • Details: Finds the value corresponding to the key in the metadata of the trigger with the given ID.

FindTriggersByDomainId

::: dev

  • Parameters: DomainId

  • Returns: Vec<Trigger>

  • Details: Finds all domain triggers for the given domain ID.

:::