Müller Equals Muller

Müller Equals Muller

A support agent types muller into the customer search and finds nothing — the customer is stored as Müller GmbH. Business Central compares what was typed against what is stored, and ü is simply not u; AL ships no diacritics-folding API, so a search that shrugs off accents, case and punctuation needs its own normalizer. You are building it.

Requirements

Create a codeunit named "Search Key Folding" with two public procedures:

procedure ToSearchKey(Input: Text): Text
procedure CountCustomersMatching(Query: Text): Integer

Pick object IDs in the 50100–50199 range, and reference other objects by name, never by ID.

ToSearchKey

Turns arbitrary text into a canonical search key. Every character of Input falls into exactly one of three classes:

• Plain letters a–z / A–Z and digits 0–9 are kept.
• A character in the fold map below is replaced by its mapped letters.
• Every other character — spaces, punctuation, dashes, symbols, and any character not covered above — is a separator.

The fold map (lowercase and uppercase fold the same):

Rules for the returned key:

1. Kept and mapped letters appear uppercased; digits appear unchanged.
2. A run of one or more separators between kept characters becomes exactly one space; separators at the start or end of the input are dropped entirely.
3. If nothing survives — the input is empty or consists only of separators — the key is the empty string.
4. A key is a fixed point: ToSearchKey(ToSearchKey(X)) equals ToSearchKey(X) for any input.

Examples: ToSearchKey('Müller GmbH') = MULLER GMBH; ToSearchKey('O''Brien & Sons, Ltd.') = O BRIEN SONS LTD; ToSearchKey('Straße 4711') = STRASSE 4711; ToSearchKey(' --Nordwind-- ') = NORDWIND.

CountCustomersMatching

1. Returns how many Customer records have a Name whose search key equals the search key of Query.
2. A Query whose search key is empty matches nothing and returns 0 — an empty key must never sweep up records.
3. The procedure never raises an error, whatever Query contains; a search that finds nothing returns 0.

What the tests check

The grading tests call ToSearchKey and compare the returned key character for character: the fold map applied to German, Nordic, French and Spanish names, every character of the fold map in both its lowercase and uppercase form, ß doubling to SS, the æ/œ ligatures, digits kept, punctuation runs collapsing to single spaces, trimmed ends, the empty and all-punctuation inputs yielding the empty string, and re-folding a key returning it unchanged. Several expected keys are built around randomly generated text, so hardcoding the examples will not pass — and plain UpperCase fails every accented case, because Ü is still not U. The lookup tests seed customers such as TRYAL-SKF1 Müller GmbH and TRYAL-SKF1 MULLER GMBH next to decoys like TRYAL-SKF1 Mueller GmbH, then assert exact counts for hits, misses, a separator-only query, and the empty query. The tests run in a real company where other customers exist — the seeded names carry unique markers, and your counts must be driven purely by the key equality described above.

Learn More

• Text data type — the toolbox for taking strings apart and putting them back together.
• Text.UpperCase(Text) method — uppercasing is the easy third of the job; notice what it does not do to accents.
• TextBuilder data type — assembling a result string piece by piece without churning memory.