> For the complete documentation index, see [llms.txt](https://aeudoc.gitbook.io/developer/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://aeudoc.gitbook.io/developer/backend/data-repository/check-exist.md).

# Check Exist

## Syntax

```
Exists(filter);
```

## Arguments

<table data-header-hidden><thead><tr><th width="136">Argument</th><th width="168">Data Type</th><th width="307">Description</th><th>Default Value</th></tr></thead><tbody><tr><td><em>filter</em></td><td>Expression&#x3C;Func&#x3C;T, bool>></td><td><p>Criteria by which the records of the repository should be filtered. </p><p>This parameter must not be empty.</p></td><td>null </td></tr></tbody></table>

## Description

Checks if repository contains any record that fulfills the criteria specified in the parameter *filter*. If there is at least one record that fulfills the criteria, it will return "true", else it will return "false".

## Example

### Example 1: Counting records by only one criterion

The following program illustrates the function call with only one criterion:

```
var isExist = repo.Exists(x => x.ProductID == "ADAM-800-BTO");
```

Function will check if repository contains any record that has "ADAM-567-BTO" as Production ID. If there is at least 1 record, then it will store the boolean value "true" into the variable isExist, else it will store the boolean value "false".

### Example 2: Filtering records by multiple criteria

The following program illustrates the function call with multiple criteria:

```
var isExist = repo.Exists(x => x.ProductID == "ADAM-800-BTO"
                            && x.Quantity > 10 
                            && x.IsUrgent == true);
```

Function will check if repository contains any record that has "ADAM-567-BTO" as Production ID, has a Quantity of more than 10 and is Urgent. If there is at least 1 record that fulfills all the criteria, then it will store the boolean value "true" into the variable isExist, else it will store the boolean value "false".