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Does anyone know how to get individual styles that have have been associated with layers in specific layer groups in GeoServer?

(Layers can have more then one style, and after you add a Layer to a Layer Group, you can choose a style for that Layer (by clicking on the style name in the list of sub-layers in the layer group). So the same Layer can use use different styles in different layer group. "A layer group also provides a consistent, fixed ordering of the layers it contains, and can specify alternate (non-default) styles for layers."- GeoServer Docs)

I am able to get nested Layer Groups via WMS GetCapabilities, but each Layer Group only contains the Layers (and their associated styles) that they contain, not which Styles are associated with which Layers in those Layer Groups.

As an example, let's say I have the following layer group structure:

- Root Layer Group
  - Layer Group A
    - layer1 using Style A
    - layer1 using Style B
  - Layer Group B
    - layer1 using Style C

So that layer1 has been added to Layer Group A twice and Layer Group B once. In Layer Group A, layer1 will be rendered once with Style A and then once with Style B. In Layer Group B, layer1 will be rendered once with Style C.

Part of the resulting GetCapabilities would look roughly like (omitting most irrelevant tags and attributes):

<Layer>
    <Title>Root Layer Group</Title>
    <Layer>
        <Title>Layer Group A</Title>
        <Layer>
            <Name>layer1</Name>
            <Style>
                <Title>Style A</Title>
            </Style>
            <Style>
                <Title>Style B</Title>
            </Style>
            <Style>
                <Title>Style C</Title>
            </Style>
        </Layer>
        <Layer>
            <Name>layer1</Name>
            <Style>
                <Title>Style A</Title>
            </Style>
            <Style>
                <Title>Style B</Title>
            </Style>
            <Style>
                <Title>Style C</Title>
            </Style>
        </Layer>
    </Layer>
    <Layer>
        <Title>Layer Group B</Title>
        <Layer>
            <Name>layer1</Name>
            <Style>
                <Title>Style A</Title>
            </Style>
            <Style>
                <Title>Style B</Title>
            </Style>
            <Style>
                <Title>Style C</Title>
            </Style>
        </Layer>
    </Layer>
</Layer>

So, I need some way to know (via an API) what alternate layer Styles are being used in each Layer Group. I am replicating the (named tree) layer group structure on the client side in javascript so that I can toggle on/off individual layers and layer groups (and display the tree structure of all layers and layer groups), but based on how I am parsing the GetCapabilities, in the example above, Style's A, B, and C all appear in both Layer Group A's publishable elements and Layer Group B's publishable elements (since I am looking at both which layers and layer group contains, and which styles are associated with each layer).

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  • I think layergroups don't have the possibility to have more than one style and they can't be changed so there is no need for the client to know what they are. Can you explain what you are trying to achieve
    – Ian Turton
    Commented Feb 8, 2023 at 9:12
  • @IanTurton layers can have more then one style, and after you add a layer to a layergroup, you can choose a style for that layer (by clicking on the style name in the list of sub-layers in the layergroup). So the same layer can use use different styles in different layergroups.
    – John
    Commented Feb 8, 2023 at 16:43
  • I've edited the question to hopefully make it clearer.
    – John
    Commented Feb 8, 2023 at 16:56

1 Answer 1

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The information I needed (which styles are associated with which published elements within a specific layer group) is provided by the GET /layergroups/{layergroupName} (or GET /workspaces/{workspace}/layergroups/{layergroup}) Geoserver REST endpoint for layers groups.

See:

The REST response for a layer group includes an array (or object in the case that there is only one published element in a layer group) of published element objects (which include a name property) in the layerGroup.publishables.published property of the response json, and includes an array (or object as noted above) of style objects (or an empty string in case the published element of the layer group uses it's default style) in the layerGroup.styles.style property. With that information you can simply zip the published and style arrays together (using their respective name properties) to get an array of associated styles and published element within a given layer group.

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