What causes ""{prefix}": namespace prefix already bound to "{uri}"" in dianping/cat?

Pick a different prefix for the new namespace binding.

dianping/cat · error · StaticError

XQST0033

XQST0033

Error message

"{prefix}": namespace prefix already bound to "{uri}"

What it means

XQST0033 is the standard XQuery error for a namespace prefix already bound to a different URI. addNamespace() resolves the requested prefix via getPrefixByPrefix lookup; if a prior binding exists and is not marked override, the new binding is rejected because re-binding a prefix to a different namespace within overlapping scope is illegal (predeclared prefixes like xml/xmlns can never be rebound).

Source

Thrown at cat-home/src/main/webapp/assets/js/editor/worker-xquery.js:1812

            return this.root.availableModuleNamespaces;
        },
        getPrefixByNamespace: function(uri){
            return this.root.namespaces[uri].prefix;
        },
        addNamespace: function (uri, prefix, pos, type) {
            if(prefix === '' && type === 'module') {
                throw new StaticWarning('W01', 'Avoid this type of import. Use import module namespace instead', pos);
            }
            if (uri === '') {
                throw new StaticError('XQST0088', 'empty target namespace in module import or module declaration', pos);
            }
            var namespace = this.getNamespace(uri);
            if (namespace && namespace.type === type && type !== 'declare' && !namespace.override) {
                throw new StaticError('XQST0047', '"' + uri + '": duplicate target namespace', pos);
            }
            namespace = this.getNamespaceByPrefix(prefix);
            if (namespace && !namespace.override) {
                throw new StaticError('XQST0033', '"' + prefix + '": namespace prefix already bound to "' + namespace.uri + '"', pos);
            }

            namespace = this.namespaces[uri];
            this.namespaces[uri] = {
                prefix: prefix,
                pos: pos,
                type: type
            };

            if (namespace) {
                throw new StaticWarning('W02', '"' + uri + '" already bound to the "' + namespace.prefix + '" prefix', pos);
            }

        },

        getNamespaces: function(){
            return this.root.namespaces;
        },

View on GitHub (pinned to e815e74d4c)

Solutions

Pick a different prefix for the new namespace binding.
Or remove/merge the earlier declaration that already claimed the prefix.
Avoid reusing well-known prefixes (fn, local, xml, xs) for your own namespaces.

Example fix

// before
declare namespace foo = "http://a.com";
import module namespace foo = "http://b.com";

// after
declare namespace foo = "http://a.com";
import module namespace bmod = "http://b.com";

Defensive patterns

Strategy: validation

Validate before calling

// Check prefix uniqueness across declarations/imports before analysis
var byPrefix = {};
bindings.forEach(function(b) {
  if (byPrefix[b.prefix] && byPrefix[b.prefix] !== b.uri) {
    warn('Prefix ' + b.prefix + ' rebound from ' + byPrefix[b.prefix] + ' to ' + b.uri);
  }
  byPrefix[b.prefix] = b.uri;
});

Try / catch

if (e.code === 'XQST0033') {
  highlight(e.pos, 'Pick a different prefix or remove the earlier binding');
}

Prevention

Use one prefix per namespace across the whole project (project-level prefix convention).
Never rebind reserved prefixes (xml, xmlns, fn, xs, local).
When merging files, dedupe the combined prolog before saving.

When it happens

Trigger: 'declare namespace foo = "U1";' followed later by 'import module namespace foo = "U2";', or two declare namespace statements using the same prefix with different URIs in the same scope chain.

Common situations: Concatenating query prologs from multiple sources; a module's internal prefix colliding with the main query's prefix; renaming refactors that leave stale declarations.

Related errors

AI-assisted analysis of dianping/cat@e815e74d4c (2026-08-14). Data as JSON: /api/errors/c73070bd2cd1ce14. Report an issue: GitHub.