Displaying Read-Only Maps in GeoDjango Admin

Based on the information available in Django 5.1 documentation, there isn't a built-in way to display an interactive map for GeoDjango fields when they're set as read-only in the admin interface. When you add a geometry field to readonly_fields, Django defaults to displaying the EWKT (Extended Well-Known Text) notation instead of the interactive map.

Possible Workaround

A common workaround for this issue is to create a custom method in your admin class that renders the map as read-only. Here's how you might implement it:

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from django.contrib.gis import admin
from django.utils.html import format_html

class TestAdmin(admin.GISModelAdmin):
    readonly_fields = ["point_map"]
    
    def point_map(self, obj):
        if obj.point:
            return format_html(
                '<div id="readonly_map" style="width: 800px; height: 400px;"></div>'
                '<script>'
                '  document.addEventListener("DOMContentLoaded", function() {{'
                '    var map = new OpenLayers.Map("readonly_map");'
                '    var osm = new OpenLayers.Layer.OSM();'
                '    map.addLayer(osm);'
                '    var vectorLayer = new OpenLayers.Layer.Vector("Features");'
                '    map.addLayer(vectorLayer);'
                '    var wkt = new OpenLayers.Format.WKT();'
                '    var feature = wkt.read("{}");'.format(obj.point.wkt) +
                '    vectorLayer.addFeatures([feature]);'
                '    map.zoomToExtent(vectorLayer.getDataExtent());'
                '  }});'
                '</script>'
            )
        return "No location data"
    
    point_map.short_description = "Location Map"

This approach:

1. Creates a custom method point_map that returns HTML and JavaScript
2. Uses OpenLayers (which GeoDjango uses by default) to render a map
3. Adds the geometry as a feature on the map
4. Sets this method as a read-only field instead of the actual geometry field

Alternative Approach

Another approach would be to override the get_readonly_fields method to conditionally include fields in the readonly list based on permissions or other criteria:

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class TestAdmin(admin.GISModelAdmin):
    def get_readonly_fields(self, request, obj=None):
        if not request.user.has_perm('app.change_model'):
            # Return all fields except geometry fields
            return [f.name for f in self.model._meta.fields if not isinstance(f, models.GeometryField)]
        return super().get_readonly_fields(request, obj)

Limitations

It's worth noting that these workarounds have limitations:

• The custom method approach requires JavaScript knowledge and may need adjustments based on your specific setup
• The map won't be as fully featured as the default GeoDjango editing map
• You'll need to ensure all necessary OpenLayers scripts are loaded

The GeoDjango form widgets are designed primarily for editing, and the read-only display functionality is limited in the current implementation.