[GIS] Openlayers bbox strategy

bboxopenlayers

I have bbox strategy for one source of data. Code looks like this:

bbox: function newBboxFeatureSource(url, typename) {
    return new ol.source.Vector({
        loader: function (extent) {
            let u = `${url}&TYPENAME=${typename}&bbox=${extent.join(",")}`;

            $.ajax(u).then((response) => {
                this.addFeatures(
                    geoJsonFormat.readFeatures(response)
                );
            });
        },
        strategy: ol.loadingstrategy.bbox
    });
},

I works fine but… When I pan/move the map then this loader is calling again and add another features which fit to new box. But there is a lot of duplicates then because some of new features are just the same as old.
So I wanted first clear all features using this.clear() before add new features but when I add this command then loader is running all the time and I have "infinitive loop". Do you know why? How can I disable loading new features after calling this.clear()?

Best Answer

To summarize the discussion in the linked question and answer the initial question:

The features sent by the server need an attribute called id, which must be unique and the same for the feature on every request.

{type: "Feature", id: "some-wfs.1234", properties: { "ogc_fid": 2, ...

See this GitHub Issue for the original comment of ahocevar.

In GeoServer this can be achieved if you set an identifier in your layer. I guess there is something similar to set in MapServer.

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