> For the complete documentation index, see [llms.txt](https://docs.umbraco.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.umbraco.com/umbraco-cms/13.latest/implementation/data-persistence.md).

# Data Persistence (CRUD)

*The Umbraco Services layer is used to query and manipulate Umbraco stored in the database*.

## Dependency injection

All services are available using their interfaces in the dependency injection container. ASP.NET Core supports dependency injection in almost every scenario.

### Constructors in classes

```csharp
    public class MyClass
    {
        private readonly IContentService _contentService;

        public MyClass(IContentService contentService)
        {
            _contentService = contentService;
        }
    }
```

### Constructors in views

```cshtml
    @inject IContentService ContentService
```

## Services

There is a service for each type of data in Umbraco.

[See here For a full list of services available](/umbraco-cms/13.latest/reference/management/services.md)


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## 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, and the optional `goal` query parameter:

```
GET https://docs.umbraco.com/umbraco-cms/13.latest/implementation/data-persistence.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

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.