Add postgreSql character length functions (#4121)

* Add Integration test for PostgreSql Dialect length function

Test for length function can be executed standalone.

Test for Nullable type support is generated

* Add Character length functions for PostgreSql Dialect

Returns number of characters in the string or will return NULL if expression is NULL.
In PostgreSql the following are synonymous and are Ansi Sql supported.
length ( In MySql the length function is in bytes )
char_length
character_length

char_length is ANSI SQL Standard and the explicitly named character_length,
as multibyte character counts as a single character not as bytes.

Examples

char_length ( text ) -> integer
char_length('jose') -> 4
char_length('海豚') -> 2
char_length(NULL) -> NULL

* Add Integration test fixture

* Add test fixture for PostgreSql length function

Support for all character length functions can be used in check constraint.

* Remove repetitive declaratiion

* Fix failing test

lowercase to compile - not sure if this should matter

* Length Function test

Shows the error

Type mismatch: inferred type is String but Int? was expected

* Revert "Length Function test"

This reverts commit 04ad12f.

dialects/postgresql/src/main/kotlin/app/cash/sqldelight/dialects/postgresql/PostgreSqlTypeResolver.kt

@@ -89,6 +89,7 @@ class PostgreSqlTypeResolver(private val parentResolver: TypeResolver) : TypeRes
     "date_trunc" -> encapsulatingType(exprList, TIMESTAMP_TIMEZONE, TIMESTAMP)
     "now" -> IntermediateType(TIMESTAMP_TIMEZONE)
     "gen_random_uuid" -> IntermediateType(PostgreSqlType.UUID)
+    "length", "character_length", "char_length" -> IntermediateType(PostgreSqlType.INTEGER).nullableIf(resolvedType(exprList[0]).javaType.isNullable)
     else -> null
   }
 

dialects/postgresql/src/test/fixtures_postgresql/alter-table-add-constraint-check/1.s

@@ -1,6 +1,12 @@
 CREATE TABLE t1 (
-  c1 INTEGER
+  c1 INTEGER,
+  t1 TEXT,
+  t2 VARCHAR(255),
+  t3 CHAR(10)
 );
 
 ALTER TABLE t1
- ADD CONSTRAINT chk_c1 CHECK (c1 > 0);
+  ADD CONSTRAINT chk_c1 CHECK (c1 > 0),
+  ADD CONSTRAINT chk_t1 CHECK (LENGTH(t1) > 0),
+  ADD CONSTRAINT chk_t2 CHECK (CHAR_LENGTH(t2) > 0),
+  ADD CONSTRAINT chk_t3 CHECK (CHARACTER_LENGTH(t3) > 0);

sqldelight-gradle-plugin/src/test/integration-postgresql/src/main/sqldelight/app/cash/sqldelight/postgresql/integration/Characters.sq

@@ -0,0 +1,13 @@
+CREATE TABLE characters(
+  name TEXT NOT NULL,
+  description TEXT
+);
+
+insertCharacter:
+  INSERT INTO characters (name, description) VALUES (:name, :description);
+
+selectNameLength:
+  SELECT length(name) FROM characters;
+
+selectDescriptionLength:
+  SELECT length(description) FROM characters;

sqldelight-gradle-plugin/src/test/integration-postgresql/src/test/kotlin/app/cash/sqldelight/postgresql/integration/PostgreSqlTest.kt

@@ -271,4 +271,12 @@ class PostgreSqlTest {
     val uuid: UUID = database.uuidsQueries.randomUuid().executeAsOne()
     assertThat(uuid).isNotNull()
   }
+
+  @Test fun lengthFunction() {
+    database.charactersQueries.insertCharacter("abcdef", null)
+    val name = database.charactersQueries.selectNameLength().executeAsOne()
+    assertThat(name).isEqualTo(6)
+    val desc = database.charactersQueries.selectDescriptionLength().executeAsOne()
+    assertThat(desc.length).isNull()
+  }
 }