Creating a Query
When a user requests data using tipQuery
or when a reporter submits data using submitValue
, they have to input both the queryId
and queryData
. The queryData
tells reporters how to fulfill the data query, while also informing voters how to verify the data in a dispute. The queryId
is defined as the keccak256 hash of the queryData
field.
In order to query the Tellor oracle you'll need to first generate the queryData
and its hash, the queryId
.
Getting a Query ID and Query Data
Use the tools below to generate a queryId
and queryData:
If the existing Query Types don't fit your needs you'll need to define a new one.
Creating a new Query Type
To create a new Query Type, or specification, for custom data you need from Tellor oracles, there's two options:
Make an issue like this and the Tellor team will help with the next steps.
Fork this repository and make a pull request for a new Query type in
./types
using this template.
To add a new data type to Tellor, you'll just need to define a new queryType . This is how you form a question so that Tellor reporters know exactly what data is being requested. You'll need to determine three things: a unique queryType name, inputs, and outputs. So let's say you want a query for getting the price of any asset in any currency. In human-readable form, your question could look like this:
What is the price of asset
in currency
?
You might formally define your query like this:
Name: SpotPrice
Inputs:
1. asset (string): Asset ID (e.g. btc)
2. currency (string): Selected currency (e.g. usd)
Outputs:
1. price (uint256)
- abi_type
: ufixed256x18 (18 decimals of precision)
- packed
: false
Once Tellor reporters are submitting your new queryType on chain, you can retrieve your desired data with the help of UsingTellor, which is a helper contract that provides various Tellor data getters. You'll first put your question in queryData
format, which means encoding your queryType name and arguments into bytes (see below). You'll then need to get a queryId
, which is the bytes32 unique identifier for each Tellor data feed. The queryId
is defined as the keccak256 hash of queryData
. Once you know the queryId
you'll be able to retrieve your data.
In Solidity, your contract can get data like this:
Example QueryData and QueryID
If you input btc
and usd
, respectively, the queryData
would be:
0x00000000000000000000000000000000000000000000000000000000000000400000000000000000000000000000000000000000000000000000000000000080000000000000000000000000000000000000000000000000000000000000000953706f745072696365000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000c0000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000800000000000000000000000000000000000000000000000000000000000000003627463000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000037573640000000000000000000000000000000000000000000000000000000000
and the queryId
would be
0xa6f013ee236804827b77696d350e9f0ac3e879328f2a3021d473a0b778ad78ac
Feel free to start building a query now and integrating it into your project. When you reach the later stages of building your project, add an issue to Tellor's dataSpecs repository so that data reporters know how to fulfill your query. Feel free to reach out to the Tellor team for assistance, and happy building!
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