UML class diagrams

Last modified: 01 September 2023

Right-click a class file or a package and select Diagrams | Show Diagram or Diagrams | Show Diagram Popup.

Enable the Diagrams plugin

This functionality relies on the Diagrams plugin, which is bundled and enabled in PyCharm by default. If the relevant features aren't available, make sure that you didn't disable the plugin.

  1. Press to open the IDE settings and then select Plugins.

  2. Open the Installed tab, find the Diagrams plugin, and select the checkbox next to the plugin name.

PyCharm lets you generate a diagram on a package in your project. Such diagrams always reflect the structure of actual classes and methods in your application.

View UML class diagram

  1. In the Project tool window, right-click an item for which you want to create a diagram and select Diagrams | Show Diagram ).

  2. In the list that opens, select Python Class Diagram. PyCharm generates a UML diagram for classes and their dependencies.

Analyze class diagram

tip

You can press on the element to view a list of diagram elements and navigate between them.

To see the list of methods, fields, and other code elements, select the appropriate icon on the diagram toolbar located on top of the diagram editor.

Py class dependencies

When you click through classes in the graph, PyCharm greys out classes that do not reside in the same package. This might be helpful, when you generate a diagram on a package that contains inner packages.

To save the diagram as a file, right-click the diagram editor and from the context menu, select Export Diagram | Export to File and then the file extension in which you want to save the diagram.

Manage class diagram

When working with diagrams, use the context menu in the diagram editor to perform different tasks. You can view members of the class, add new, delete the existing ones, see implementations, check parent classes, perform basic refactoring, add notes, and so on.

You can navigate to the underlying source code by selecting a diagram element and pressing ).

Add an existing class to a diagram

  1. Press .

  2. In the search field that opens, start typing a name of the class you want to add. Then, select the desired class from the suggestion list.

    https://resources.jetbrains.com.cn/help/img/idea/2023.2/py_umlPopup.png
    Gif

    If you want to add a class that is out of the project scope, select the Include non-project items checkbox.

Delete a node element from the diagram

  1. In the diagram editor, select a node element you want to delete.

  2. Right-click the element and from the context menu, select Delete .

    Alternatively, select Refactor | Safe Delete . In this case, PyCharm checks for usages before applying the changes.

tip

You can quickly search for usages by pressing on a code element.

Add new members to a class

You can perform some forward engineering while in the diagram editor.

  1. In the diagram editor, select a class to which you want to add a new member and from the context menu, select New or press . Then select a code element (a field or a method) you want to create.

  2. Depending on your selection, PyCharm opens the appropriate dialog where you specify the necessary information for creating the new element.

PyCharm adds the item to your diagram and updates the source code accordingly.

View implementations and parent classes

You can view implementations and parent classes in your diagram. If PyCharm finds more than one parent class or implementation, it displays a list of appropriate items. Select the one you need to see the connections between the parent and its children.

  1. In the diagram editor, select an item for which you want to see implementations or parent classes.

  2. Right-click the items and from the context menu, select the Show Implementations or Show Parents respectively.

  3. In the popup that opens, select items you need and press . To extend your selection up or down while in the popup, press Shift+Up or Shift+Down respectively.

Configure diagram settings

You can configure the diagram settings so that you have certain options available by default when you create a diagram.

  1. Press to open the IDE settings and then select Tools | Diagrams.

  2. In the right-hand pane, select the options that you want to see by default and click OK to apply your changes.

Analyze graph

The Analyze Graph action group lets you analyze the graph in various ways such as perform auto clusterization, measure the node centrality, search cycles, filter path between two nodes, and so on.

Filter paths between two nodes

Most of the time, generated diagrams are big and complicated. Typically, you want to concentrate only on the specific part of the diagram. PyCharm lets you filter paths between two diagram elements.

  1. In the diagram editor, select two nodes on which you want to focus and right-click one of them to open the context menu.

  2. From the context menu, select Analyze Graph | Focus On Paths Between Two Nodes.

    note

    If you want to focus not only on just two nodes, but on how the selected node is connected with its neighbors, select the Focus on Node Neighborhood option from the context menu.

  3. In the dialog that opens, select additional options if needed and click Find.

    PyCharm displays connections associated only with the selected nodes.

Measure diagram centrality

You can use this action to identify the important nodes in the graph.

  1. In the diagram editor, right-click anywhere in the editor to open the context menu.

  2. From the context menu, select Analyze Graph | Measure Centrality.

  3. In the dialog that opens, select additional options if needed and click Measure.

    The node "importance" is expressed via fractional value from 0.0 to 1.0 measurement, and the brightest node selection should be explored first.

tip

Press to cancel the actions.

Productivity tips

Enable the diagram preview

Open the Structure tool window and drag the shadow area to obtain the desired view. Select one or more nodes in the diagram to highlight the corresponding nodes in the preview area.

Manage diagram layout

Right-click the diagram background, and choose Layout from the context menu. Then select the desired layout from the submenu. To apply the selected layout, click the Apply Current Layout button on the diagram toolbar.

Alternatively, drag entities in the diagram manually to achieve the desired layout.

Zoom in and out

Use any of the following techniques:

  • Click the Zoom In button and the Zoom Out button on the diagram editor toolbar.

  • Keeping pressed, rotate your mouse wheel.

  • Press or .

Use the magnifier tool

Keeping pressed, hover over diagram areas.

View the structure of a database or table as a diagram

In the Database tool window, right-click a schema or a table and select Diagrams | Show Visualization or Diagrams | Show Visualization Popup from the context menu.

View SQL query plan as a diagram

In the editor, right-click an SQL statement and select Explain Plan. Then, in the Output pane, switch to the Plan tab. By default, the query is displayed as a tree. To see it as a diagram, click Show Visualization (the Show Visualization button) or press .