# Using off-chain data

This page shows how to enrich your Mimic functions with **off‑chain data**. You’ll learn three common patterns:

1. **Pricing** convert token balances to USD
2. **Discovery of relevant tokens** for a user across a chain and bulk‑transfer them
3. **Custom subgraph queries** (e.g., fetch a Uniswap pool price)

We’ll walk through each pattern, the inputs they require, and implementation details you should keep in mind (precision, slippage, and fees).

> Pre-reqs: You’ve already read the basic function guide and can `mimic codegen`, `mimic compile`, and `mimic deploy`.

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### Use price feeds to act on a USD threshold

**Goal:** Top up a recipient if their token balance (in USD) falls below a threshold.

{% @github-files/github-code-block url="<https://github.com/mimic-protocol/examples/blob/main/examples/04-transfer-balance-threshold-with-oracles/src/function.ts>" visible="false" %}

[Github link](https://github.com/mimic-protocol/examples/blob/main/examples/04-transfer-balance-threshold-with-oracles/src/function.ts)

**Notes**

* Convert all human‑readable decimals using `BigInt.fromStringDecimal(value, decimals)` to avoid precision loss.
* `maxFee` is specified in token units here; pass a USD‑denominated cap instead by using `TokenAmount.fromStringDecimal(DenominationToken.USD(), ...)` (see next example).

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### Find relevant tokens and send them in one go

**Goal**: Detect which tokens a user actually holds on a chain and transfer any non‑zero balances to a recipient, paying a single USD‑capped fee.

{% @github-files/github-code-block url="<https://github.com/mimic-protocol/examples/blob/main/examples/08-relevant-tokens-query/src/function.ts>" visible="false" %}

[Github link](https://github.com/mimic-protocol/examples/blob/main/examples/08-relevant-tokens-query/src/function.ts)

**Notes**

* `getRelevantTokens` helps you focus on balances that matter. Supply an allow‑list if you want strict control over which tokens are considered.
* The fee cap is set in **USD** via `DenominationToken.USD()`; the runtime handles conversion.

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### Query a subgraph for price and swap with slippage

**Goal**: Fetch a Uniswap pool price from a subgraph, compute expected output, apply slippage in BPS, and submit a swap intent.

{% @github-files/github-code-block url="<https://github.com/mimic-protocol/examples/blob/main/examples/09-subgraph-query/src/function.ts>" visible="false" %}

[Github link](https://github.com/mimic-protocol/examples/blob/main/examples/09-subgraph-query/src/function.ts)

**Why `PRICE_PRECISION = 40`?**

* Subgraph prices are strings with decimal precision. We parse them into a big integer using a high fixed precision (40) to minimize rounding error before scaling to token decimals. Match this with your downstream math so `upscale/downscale` lands on correct integer units.

**Slippage in BPS**

* `slippageBps = 50` → 0.50% buffer. We compute `minAmountOut = expectedOut * (1 − bps/10_000)`.

**Edge cases**

* Ensure the pool exists (`data.pools.length > 0`).
* Consider stable pools whose price may deviate
* Handle tokens with non‑standard decimals (e.g., 6, 8).