Parse boolean

Author: razor-x

README.md

@@ -19,9 +19,12 @@ However, some additional input cases are handled:
 
 - For `z.number()`, `z.boolean()`, `z.date()`, `z.object()`, and `z.record()`,
   whitespace only values are parsed as `null`.
-- For `z.boolean()`:
-    - `1`, `True`, and `TRUE` are all parsed as `true`
-    - `0`, `False`, and `FALSE` are all parsed as `true`
+- For `z.number()`, `z.boolean()`, `z.date()`,
+  starting and ending whitespace is trimmed  before parsing.
+- For `z.boolean()`, the following values are parsed as `true`:
+    -
+- For `z.boolean()`, the following values are parsed as `false`:
+    -
 - Parses `z.array()` in the following formats.
   In order to support unambiguous parsing, array string values
   containing a `,` are not supported.

src/lib/parse.test.ts

@@ -24,6 +24,11 @@ test('parseUrlSearchParams: with URLSearchParams input', (t) => {
   )
 })
 
+test.todo('pass though number values that parse as NaN')
+test.todo(
+  'pass though boolean values that do not parse as truthy or falsy values',
+)
+
 // e.g., foo.bar= would conflict with foo.bar.a= or foo.bar.b=2
 // since this would be a null object containing values (null is still a value).
 test.todo('cannot parse conflicting object keys')

src/lib/parse.ts

@@ -49,24 +49,35 @@ const parseFromParamSchema = (
 }
 
 const parse = (k: string, values: string[], type: ValueType): unknown => {
-  // TODO: Add better errors with coercion. If coercion fails, passthough?
   if (values.length === 0) return undefined
 
   if (values[0] == null) {
     throw new Error(`Unexpected nil value when parsing ${k}`)
   }
 
-  if (type === 'number') return parseNumber(values[0])
-  if (type === 'boolean') return values[0] === 'true'
+  if (type === 'number') return parseNumber(values[0].trim())
+  if (type === 'boolean') return parseBoolean(values[0].trim())
   if (type === 'string') return String(values[0])
   if (type === 'string_array') return values
   if (type === 'number_array') return values.map((v) => Number(v))
   throw new UnparseableSearchParamError(k, 'unsupported type')
 }
 
-const parseNumber = (v: string): number | null => {
-  if (v.trim().length === 0) return null
-  return Number(v)
+const parseNumber = (v: string): number | null | string => {
+  if (v.length === 0) return null
+  const n = Number(v)
+  if (isNaN(n)) return v
+  return n
+}
+
+const truthyValues = ['true', 'True', 'TRUE', 'yes', 'Yes', 'YES', '1']
+const falsyValues = ['false', 'False', 'FALSE', 'no', 'No', 'NO', '0']
+
+const parseBoolean = (v: string): boolean | null | string => {
+  if (v.length === 0) return null
+  if (truthyValues.includes(v)) return true
+  if (falsyValues.includes(v)) return false
+  return v
 }
 
 export class UnparseableSearchParamError extends Error {

test/generous-parsing.test.ts

@@ -11,19 +11,28 @@ const parseEmptyOrWhitespace = test.macro({
     const schema = z.object({ foo: type })
     const expected = { foo: null }
     t.deepEqual(parseUrlSearchParams('foo=', schema), expected)
+    t.deepEqual(parseUrlSearchParams('foo= ', schema), expected)
+    t.deepEqual(parseUrlSearchParams('foo=  ', schema), expected)
     t.deepEqual(parseUrlSearchParams('foo=%20', schema), expected)
-    t.deepEqual(parseUrlSearchParams('foo= %20 ++ +  ', schema), expected)
+    t.deepEqual(parseUrlSearchParams('foo=%20%20%20', schema), expected)
     t.deepEqual(parseUrlSearchParams('foo=+', schema), expected)
+    t.deepEqual(parseUrlSearchParams('foo=+++', schema), expected)
+    t.deepEqual(parseUrlSearchParams('foo= %20 ++ +%20 ', schema), expected)
   },
 })
 
 test('number', parseEmptyOrWhitespace, z.number())
+test('boolean', parseEmptyOrWhitespace, z.boolean())
 
 test.todo('parse empty or whitespace boolean params as null')
 test.todo('parse empty or whitespace date params as null')
 test.todo('parse empty or whitespace object params as null')
 test.todo('parse empty or whitespace record params as null')
 
+test.todo('trim whitespace before parsing number params')
+test.todo('trim whitespace before parsing boolean params')
+test.todo('trim whitespace before parsing date params')
+
 test.todo('parse empty or whitespace array params as empty')
 test.todo(
   'cannot parse multiple empty or whitespace array params like foo=&foo=',