# 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)


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# 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.umbraco.com/umbraco-cms/13.latest/implementation/data-persistence.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.