> For the complete documentation index, see [llms.txt](https://appmaster.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://appmaster.gitbook.io/docs/data-design/relation-types.md).

# Relation types

Working with the data model designer.

Relationships can be established between two data models - to determine how objects created from them will relate to each other and interact. There are three types of such links:

* **has\_one** - 1 object created from data model A, can be associated with only 1 object created from data model B; 
* **has\_many** - 1 object created from data model A, can be associated with several objects created from data model B; 
* **many\_to\_many** - a set of objects created from data model A can be associated with many objects created from data model B. 

Linked Data Models gain additional capabilities for collaborative processing in your application. One data model can be associated with an infinite number of others - the main thing is not to complicate the logic of connections so much that you cannot figure it out.