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Solidity: Create a Query

Create a new oracle query by scheduling a start block, providing the question and metadata, and selecting the number of options. This page covers on-chain usage only (no deployment, governance, or meta info).

Requirements:

  • Your contract holds the governance token and has approved the oracle to pull the creation deposit (see ../solidity/approvals).
  • startBlock >= block.number
  • totalOptions in [2..255]

Minimal interfaces

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

interface IOracleCreate {
    function createQuery(
        uint256 startBlock,
        string calldata question,
        string calldata metadata,
        uint8 totalOptions
    ) external returns (uint256);
}

Single-purpose creator

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

interface IOracleCreate {
    function createQuery(uint256, string calldata, string calldata, uint8) external returns (uint256);
}

contract OracleCreate {
    IOracleCreate public immutable oracle;

    constructor(address oracle_) {
        oracle = IOracleCreate(oracle_);
    }

    /// @notice Open a query scheduled to start after `startOffsetBlocks` from now.
    /// @dev Assumes this contract already approved the oracle to pull the deposit.
    function openQuery(
        uint256 startOffsetBlocks,
        string calldata question,
        string calldata metadata,
        uint8 totalOptions
    ) external returns (uint256 queryId) {
        uint256 startBlock = block.number + startOffsetBlocks;
        queryId = oracle.createQuery(startBlock, question, metadata, totalOptions);
    }
}

Notes:

  • The oracle pulls the fixed creation deposit from msg.sender using transferFrom. Ensure you approved the oracle and the contract holds enough tokens.
  • The query remains “pending” until the first vote arrives, then moves to “active”.

Metadata tips

Use a small JSON string in metadata to help indexers/UIs:

// Example metadata string (JSON)
// {"topic":"markets","tag":"demo-1","link":"https://example.com/context"}

Keep it short to avoid excessive gas.

Common pitfalls

  • Missing allowance: call token approve(oracle, amount) first.
  • startBlock in the past: compute block.number + offset.
  • Invalid totalOptions: must be within [2..255].
  • Overly long question/metadata: impacts gas and may exceed internal gas limits for complex transactions.

Related pages

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