Drupal 8 Module Development - Second Edition

The structure of a render array

Render arrays are rendered by the renderer service (RendererInterface), which traverses the array and recursively renders each level. Each level of the array can have one or more elements, which can be of two types: properties or children. The properties are the ones whose keys are preceded by a # sign, whereas children are the ones that are not. The children can themselves be an array with properties and children. However, each level needs to have at least one property in order to be considered a level because it is responsible for telling the render system how that level needs to be rendered. As such, property names are specific to the Render API and to the actual thing they need to render, while the names ...