---
title: "The import"
manual: "TYPO3 EXT:thuecat"
version: "main"
permalink: "https://docs.typo3.org/permalink/werkraummedia/thuecat:developers-import@main"
source: "Developers/Import/Index.rst"
rendered: "2026-10-09T11:47:03+00:00"
---

# The import {#developers-import}

This chapter is for developers who extend the import: a new record kind, a new property, a new
relation, or a new way to select what gets imported. It explains the concepts the import is built on
and the rules a change has to keep. For which class does what, read the code; the pages here explain
why it is shaped the way it is.

How to configure and run an import is described for integrators in [Import Data from ThueCat](https://docs.typo3.org/permalink/werkraummedia/thuecat:import@main).

## Terms used throughout {#terms-used-throughout}

-   **Run**

    One execution of one import configuration record, from the first request to the import log.

-   **Root**

    An upstream object the import configuration asks for directly, by URL. A run has one or more
    roots.

-   **Entity**

    A parser for one kind of upstream object. It turns one JSON-LD node into one database row of one
    table.

-   **Reference**

    A relation the upstream data expresses by `@id` only, such as the town an attraction lies in.
    The entity cannot resolve it on its own and leaves it for the resolver.

-   **Payload**

    Everything a run has parsed and is about to write: rows, translations, open references, commands.
    It is handed to the TYPO3 DataHandler at the end.

-   **Round**

    One pass of the DataHandler over the payload. A run needs several, see
    [Why persisting takes several rounds](https://docs.typo3.org/permalink/werkraummedia/thuecat:developers-import-run-rounds@main).

-   [How a run works](https://docs.typo3.org/permalink/werkraummedia/thuecat:how-a-run-works@main)
-   [Records, identity and languages](https://docs.typo3.org/permalink/werkraummedia/thuecat:records-identity-and-languages@main)
-   [Adding a record kind](https://docs.typo3.org/permalink/werkraummedia/thuecat:adding-a-record-kind@main)
-   [Relations](https://docs.typo3.org/permalink/werkraummedia/thuecat:relations@main)
-   [Values stored as category trees](https://docs.typo3.org/permalink/werkraummedia/thuecat:values-stored-as-category-trees@main)
-   [Media files](https://docs.typo3.org/permalink/werkraummedia/thuecat:media-files@main)
-   [The import log](https://docs.typo3.org/permalink/werkraummedia/thuecat:the-import-log@main)
-   [What a run imports](https://docs.typo3.org/permalink/werkraummedia/thuecat:what-a-run-imports@main)
-   [Import tuning](https://docs.typo3.org/permalink/werkraummedia/thuecat:import-tuning-1@main)
-   [Testing an import](https://docs.typo3.org/permalink/werkraummedia/thuecat:testing-an-import@main)