# Utilising CirclesQuery Class

The previously shown `CirclesData` class returns `CirclesQuery<T>` objects for all paged query results. You can execute custom queries against all tables in the Circles index and filter with them.

### Write a query

First you'll need to define a query. The basic structure of a query is the same as for a basic SQL select. It has the following fields:

* `namespace`: Used to distinguish between tables and views as well and to tell the tables of the two Circles version apart from each other.
* `table`: The name of the table you want to query.
* `columns`: A list of column names you want to select.
* `filter`: A list of filter conditions that must be met.
* `sortOrder`: Can be 'asc' or 'desc'.
* `limit`: How many rows to return (max: 1000).

{% hint style="info" %}
Check out the documentation of the [`circles_query`rpc method](https://github.com/aboutcircles/circles-nethermind-plugin/tree/dev?tab=readme-ov-file#circles-nethermind-plug-in) for a list of tables.
{% endhint %}

Here is a query that reads all avatars with type `group`. Other avatar types you can try are `human` and `organization`.

```typescript
const queryDefinition: PagedQueryParams = {
  namespace: 'V_Crc',
  table: 'Avatars',
  columns: [
    'blockNumber',
    'transactionIndex',
    'logIndex',
    'avatar',
    'name',
    'cidV0Digest'
  ],
  filter: [
    {
      Type: 'FilterPredicate',
      FilterType: 'Equals',
      Column: 'type',
      Value: 'group'
    }
  ],
  sortOrder: 'ASC',
  limit: 100
};
```

{% hint style="warning" %}
If you want to be able to load the next page (`queryNextPage()`) you must always include the following fields in your query:`blockNumber`, `transactionIndex, logIndex.`
{% endhint %}

### Define a row type

You can define a type for the rows of your query, or just go with `any` if the type doesn't matter.

If you want to specify a custom type, it must extend the `EventRow` type. The `EventRow` type contains the `blockNumber`, `transactionIndex` and `logIndex` fields which are required for pagination.

```typescript
interface MyGroupType extends EventRow {
  avatar: string;
  name: string;
  cidV0Digest?: string;
}
```

### Execute the query

To execute the query definition, you'll need a `CirclesRpc` instance. Create one and pass the Circles rpc url to the constructor.

```typescript
const circlesRpc = new CirclesRpc('https://rpc.aboutcircles.com/');
```

Then create a `CirclesQuery<MyGroupType>` instance.

```typescript
const query = new CirclesQuery<MyGroupType>(circlesRpc, queryDefinition);
```

Call `getNextPage()` to retrieve the first page of the result set. You can then access the results through the `currentPage` property. This property includes the `results` themselves, along with `firstCursor`, `lastCursor`, `limit`, `size`, and `sortOrder`.

```typescript
const hasResults = await query.queryNextPage();
if (!hasResults) {
  console.log("The query yielded no results.");
} else {
  const rows = query.currentPage.results;
  rows.forEach(row => console.log(row));
}
```

### Add computed columns

You can extend the CirclesQuery with computed columns. Computed columns are defined by a callback that takes in the row and returns a new value. Here we convert the value of the previously queried `cidV0Digest` field (which is originally a hex-string) to a CID in `Qm..` format.

```typescript
const calculatedColumns = [{
  name: 'cidV0',
  generator: async (row: MyGroupType) => {
    if (!row.cidV0Digest) {
      return undefined;
    }

    const dataFromHexString = hexStringToUint8Array(row.cidV0Digest.substring(2));
    return uint8ArrayToCidV0(dataFromHexString);
  }
}];
```

The new column should be added to the custom type.

```typescript
interface MyGroupType extends EventRow {
  avatar: string;
  name: string;
  cidV0Digest?: string;
  cidV0?: string
}
```

Then you can execute the query just like you did before. The calculated column function will be executed for each row in a page.

```typescript
const query = new CirclesQuery<MyGroupType>(circlesRpc, queryDefinition, calculatedColumns);

const hasResults = await query.queryNextPage();
if (!hasResults) {
  console.log("The query yielded no results.");
} else {
  const rows = query.currentPage.results;
  rows.forEach(row => console.log(row));
}
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.aboutcircles.com/querying-circles-profiles-and-data/utilising-circlesquery-class.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.