feat: config options for fuzzy search

hana/lib/cql-functions.js

@@ -24,10 +24,39 @@ const StandardFunctions = {
   contains: (...args) => args.length > 2 ? `CONTAINS(${args})` : `(CASE WHEN coalesce(locate(${args}),0)>0 THEN TRUE ELSE FALSE END)`,
   concat: (...args) => `(${args.map(a => (a.xpr ? `(${a})` : a)).join(' || ')})`,
   search: function (ref, arg) {
+    const csnElements = ref.element ? [ref] : [...ref.list]
+    let fuzzyString
+
+    // default config
+    const fuzzyIndex = cds.env.hana?.fuzzy || 0.7
+
+    // if column specific value is provided, the configuration has to be defined on column level
+    if (csnElements.some(e => e.element?.['@Search.ranking'] || e.element?.['@Search.fuzzinessThreshold'])) {
+      const cols = csnElements.map(e => {
+        // REVISIT: How to do quoting?
+        let col = `${e.ref.join('.')} FUZZY`
+
+        const rank = e.element?.['@Search.ranking']?.['=']
+        if(rank === 'HIGH') col += ' WEIGHT 0.8'
+        else if(rank === 'LOW') col += ' WEIGHT 0.3'
+        else col += ' WEIGHT 0.5' // MEDIUM
+
+        col+= ` MINIMAL TOKEN SCORE ${e.element?.['@Search.fuzzinessThreshold'] || fuzzyIndex}`
+        col+= " SIMILARITY CALCULATION MODE 'search'"
+        return col
+      }).join(',')
+
+      fuzzyString = `(${cols})`
+    } else {
+      fuzzyString = `${ref} FUZZY MINIMAL TOKEN SCORE ${fuzzyIndex} SIMILARITY CALCULATION MODE 'search'`
+    }
+
+
+
     // REVISIT: remove once the protocol adapter only creates vals
     if (Array.isArray(arg.xpr)) arg = { val: arg.xpr.filter(a => a.val).map(a => a.val).join(' ') }
-    // REVISIT: make this more configurable
-    return (`(CASE WHEN SCORE(${arg} IN ${ref} FUZZY MINIMAL TOKEN SCORE 0.7 SIMILARITY CALCULATION MODE 'search') > 0 THEN TRUE ELSE FALSE END)`)
+
+    return (`(CASE WHEN SCORE(${arg} IN ${fuzzyString}) > 0 THEN TRUE ELSE FALSE END)`)
   },
 
   // Date and Time Functions