# mgps

A module containing utility functions for general purpose tasks.

| Trait               | Value      |
| ------------------- | ---------- |
| **Module type**     | util       |
| **Implementation**  | Python     |
| **Parallelism**     | sequential |

## Functions

### `validate_predicate()`

Raises an exception if the given predicate yields `true`; otherwise returns
`true`. This is useful when checking assertions in `WHERE` clauses, because it
means you can filter out data that doesn't meet your validation criteria, and
provide an error if the validation fails for a specific reason you want to
highlight.

> **Info**
>
> This function is equivalent to **apoc.util.validatePredicate**.

#### Input:

- `predicate: boolean` ➡ Predicate condition to evaluate.
- `message: string` ➡ The text of the error message raised if the predicate
yields `true`. This can contain placeholder, such as `%s`, which are
interpolated from the `params` argument.
- `params: list` ➡ The list of parameters to substitute into placeholders in `message`.

#### Output:

- `true: boolean` ➡ This function either returns `true`, or aborts the query by
raising an exception.

#### Usage:

Use the following query to validate that `age` is never negative, and to raise
an exception if the predicate is `true`.

```cypher
MATCH (n:User)
WHERE mgps.validate_predicate(n.age < 0, "Invalid age: %i", [n.age])
RETURN n;
```

### `await_indexes()`

A no-op compatibility shim for Neo4j's `db.awaitIndexes`. Some clients
(notably the Neo4j Spark / PySpark connector) call `db.awaitIndexes`
during initialization to block until pending indexes are online. Memgraph
builds indexes synchronously, so there is nothing to wait for — this
procedure exists purely so those clients can connect without changes.

> **Info**
>
> This procedure is equivalent to **db.awaitIndexes**.

#### Input:

- `seconds: integer` ➡ Accepted for parity with the Neo4j signature.
  The value is ignored.
  
```Cypher
CALL mgps.await_indexes(300);
```

### `version()`

Returns the Memgraph server version as a string. Provided as the Memgraph
equivalent of `apoc.version` for compatibility with Neo4j-style clients.

> **Info**
>
> This function is equivalent to **apoc.version**.

#### Output:

- `version: string` ➡ The Memgraph server version.

#### Usage:

```cypher
RETURN mgps.version();
```