---
last_review: "2026-05-06"
last_reviewer: "s.kaviani"
documented_code: [ ]
---

```{tags} advanced-user, tutorial, schema
```

% Issue: https://gitlab.indiscale.com/caosdb/src/linkahead-docs/-/issues/72

# Creating a Data Model

This tutorial covers creating a simple LinkAhead data model using PyLinkAhead, including Properties,
RecordTypes, and inheritance hierarchies.

| Concept                                 | PyLinkAhead                                |
|-----------------------------------------|--------------------------------------------|
| Create a Property                       | `db.Property(name=..., datatype=...)`      |
| Create a RecordType                     | `db.RecordType(name=...)`                  |
| Add a Property to a RecordType          | `.add_property()`                          |
| Insert a single entity into LinkAhead   | `.insert()`                                |
| Insert multiple entities into LinkAhead | `db.Container().extend([...]).insert()`    |
| Create a child RecordType               | `.add_parent(name=..., inheritance="all")` |
| Check inherited property importance     | `.get_importance()`                        |
| Declare a list-typed Property           | `db.LIST()`                                |

## Prerequisites

Make sure you have completed [First Steps with PyLinkAhead](first_steps.md) and have access to a
writable LinkAhead instance. Import the client and configure your connection as shown
in [First Steps](first_steps.md).

## Properties and RecordTypes

A {term}`Data Model` in LinkAhead is built from RecordTypes and Properties; for a conceptual
overview see [LinkAhead Data Model](/explanation/general/data-model.md).

Create a Property of datatype double:

```{literalinclude} /.assets/tests/tutorials/pylib/test_data_insertion.py
:start-after: "# ---- LINK-1 ----"
:end-before: "# ---- LINK-2 ----"
:language: python
:dedent:
```

To insert multiple entities at once, add them to a `Container` and call `.insert()` once. The
following example builds a RecordType with three properties:

```{literalinclude} /.assets/tests/tutorials/pylib/test_data_insertion.py
:start-after: "# ---- LINK-2 ----"
:end-before: "# ---- LINK-3 ----"
:language: python
:dedent:
```

```{code-block} text
:caption: Output:
:class: text-output

101
```

Objects are created locally in Python and become part of the LinkAhead instance only after
`.insert()` is called. The printed value is the server-assigned ID; the actual value depends on the
state of your instance.

### Inheritance of Properties

For a conceptual explanation, see
[Property Inheritance](/explanation/general/data-model.md#property-inheritance).

To create a child RecordType that inherits all properties from a parent, use `.add_parent()` with
`inheritance="all"`:

```{literalinclude} /.assets/tests/tutorials/pylib/test_data_insertion.py
:start-after: "# ---- LINK-3 ----"
:end-before: "# ---- LINK-4 ----"
:language: python
:dedent:
```

```{code-block} text
:caption: Output:
:class: text-output

RECOMMENDED
```

`.get_importance()` returns the importance level the server assigned to the inherited property.
`RECOMMENDED` is the default for properties inherited with `inheritance="all"`.

:::{note}
The inherited properties are only visible after insertion, since they are set by the LinkAhead
server, not by the Python client.
:::

## List Properties

To declare a Property that holds multiple values, use `db.LIST()` wrapping the element datatype:

```{literalinclude} /.assets/tests/tutorials/pylib/test_data_insertion.py
:start-after: "# ---- LINK-26 ----"
:end-before: "# ---- LINK-27 ----"
:language: python
:dedent:
```

The same `db.LIST()` syntax works in `.add_property()` when building a RecordType that uses the
property:

```{literalinclude} /.assets/tests/tutorials/pylib/test_data_insertion.py
:start-after: "# ---- LINK-27 ----"
:end-before: "# ---- LINK-28 ----"
:language: python
:dedent:
```

The element type can be any scalar datatype (`db.DOUBLE`, `db.INTEGER`, `db.TEXT`, etc.) or a
RecordType name for properties that hold references to multiple records of that type. For example, a
`Study` RecordType whose `experiments` property references multiple `Experiment` records:

```{literalinclude} /.assets/tests/tutorials/pylib/test_data_insertion.py
:start-after: "# ---- LINK-28 ----"
:end-before: "# ---- LINK-29 ----"
:language: python
:dedent:
```

## Summary

This tutorial covered creating Properties and RecordTypes, inserting them as a group, setting up
RecordType hierarchies using inheritance, and declaring list-typed Properties.

Continue with [Inserting Records](inserting_records.md) to insert, reference, and update records in
LinkAhead.