---
title: Errors
description: Sentinel errors returned by Grove operations.
---

Grove defines sentinel errors for all failure cases. Use `errors.Is()` to check for specific errors.

## Query Errors

| Error | Description |
|-------|-------------|
| `ErrNoRows` | Query returned no rows (similar to `sql.ErrNoRows`) |
| `ErrModelNotRegistered` | Model type was not registered via `RegisterModel()` |
| `ErrNotSupported` | Operation not supported by the current driver |

## Driver Errors

| Error | Description |
|-------|-------------|
| `ErrDriverClosed` | Driver connection pool has been closed |
| `ErrTxDone` | Transaction has already been committed or rolled back |
| `ErrInvalidDSN` | Data source name is malformed |

## Migration Errors

| Error | Description |
|-------|-------------|
| `ErrMigrationFailed` | A migration function returned an error |
| `ErrMigrationLocked` | Another process holds the migration lock |
| `ErrCyclicDependency` | Migration group dependencies form a cycle |
| `ErrDuplicateVersion` | Two migrations share the same version string |

## Hook Errors

| Error | Description |
|-------|-------------|
| `ErrHookDenied` | A privacy hook returned `Decision: Deny` |
| `ErrHookPanic` | A hook panicked during execution (recovered) |

## Schema Errors

| Error | Description |
|-------|-------------|
| `ErrInvalidTag` | Struct tag has invalid syntax |
| `ErrNoPrimaryKey` | Model has no field marked as `pk` |
| `ErrInvalidRelation` | Relation definition is incomplete or incorrect |

## Usage

```go
import "github.com/xraph/grove"

var users []User
err := db.NewSelect(&users).
    Where("active = $1", true).
    Scan(ctx)

if errors.Is(err, grove.ErrNoRows) {
    // No matching users found
}

if errors.Is(err, grove.ErrModelNotRegistered) {
    // Forgot to call db.RegisterModel((*User)(nil))
}
```

## Wrapping

All errors returned by Grove wrap the underlying driver error when available:

```go
err := db.NewSelect(&users).Scan(ctx)
if err != nil {
    // Unwrap to get the original pgx/mysql error
    var pgErr *pgconn.PgError
    if errors.As(err, &pgErr) {
        fmt.Println(pgErr.Code) // e.g., "23505" for unique violation
    }
}
```