How to Fix PostgreSQL Error: Invalid Input Syntax for Type

The "Invalid input syntax for type" error occurs when attempting to insert or cast a value that cannot be converted to the target data type. This indicates data format doesn't match expected type.

Impact

Prevents data insertion or queries from executing, commonly occurring during data imports, user input processing, or type conversions.

Common Causes

1. Non-numeric string for numeric types
2. Invalid date/time format
3. Malformed JSON
4. Boolean values not recognized
5. Empty strings for numeric types
6. Wrong delimiter in arrays

Troubleshooting and Resolution Steps

1. Validate numeric input:

   -- ERROR: invalid input syntax for type integer: "abc"
   INSERT INTO products (quantity) VALUES ('abc');
   
   -- FIX: Validate before insert
   INSERT INTO products (quantity) VALUES (CASE
       WHEN 'abc' ~ '^[0-9]+$' THEN 'abc'::INTEGER
       ELSE NULL
   END);
   
   -- Or use NULLIF for empty strings
   INSERT INTO products (quantity) VALUES (NULLIF('', '')::INTEGER);
   

2. Handle date/time formats:

   -- ERROR: invalid input syntax for type date: "2024-13-01"
   INSERT INTO events (event_date) VALUES ('2024-13-01');
   
   -- FIX: Use correct format or validate
   INSERT INTO events (event_date) VALUES ('2024-01-13');
   
   -- Try to cast, return NULL if invalid
   SELECT
       CASE
           WHEN value ~ '^\d{4}-\d{2}-\d{2}$'
           THEN value::DATE
           ELSE NULL
       END
   FROM source_table;
   

3. Validate in application before insert:

   # Python validation
   def safe_int_convert(value):
       try:
           return int(value) if value else None
       except ValueError:
           return None
   
   quantity = safe_int_convert(user_input)
   cursor.execute(
       "INSERT INTO products (quantity) VALUES (%s)",
       (quantity,)
   )
   

4. Handle boolean values:

   -- ERROR: invalid input syntax for type boolean: "yes"
   UPDATE settings SET enabled = 'yes';
   
   -- FIX: Use proper boolean values
   UPDATE settings SET enabled = TRUE;
   
   -- Or convert strings
   UPDATE settings SET enabled = CASE
       WHEN value IN ('yes', 'true', '1', 't') THEN TRUE
       WHEN value IN ('no', 'false', '0', 'f') THEN FALSE
       ELSE NULL
   END;
   

5. Use try-catch in functions:

   CREATE OR REPLACE FUNCTION safe_cast_int(text_val TEXT)
   RETURNS INTEGER AS $$
   BEGIN
       RETURN text_val::INTEGER;
   EXCEPTION WHEN OTHERS THEN
       RETURN NULL;
   END;
   $$ LANGUAGE plpgsql;
   
   SELECT safe_cast_int('123');  -- Returns 123
   SELECT safe_cast_int('abc');  -- Returns NULL
   

Additional Information

• Always validate data before insertion
• Use application-level validation as first defense
• Consider CHECK constraints for validation
• Empty strings often cause this error
• Use proper date format: YYYY-MM-DD
• Test with edge cases and invalid data

Frequently Asked Questions

Q: How do I handle empty strings for numeric fields?
A: Use NULLIF: NULLIF('', '')::INTEGER or validate in application to convert empty strings to NULL.

Q: What's the correct date format for PostgreSQL?
A: ISO format YYYY-MM-DD is standard. Use TO_DATE() or cast with proper format for other formats.

Q: Can I make PostgreSQL more lenient with type conversion?
A: No, PostgreSQL is intentionally strict. Implement validation logic in your application or use exception handling in functions.