0
# Error Handling
1

2
Comprehensive exception hierarchy for handling all types of errors that can occur during GRIB/BUFR processing, from file access issues to data validation failures.
3

4
## Exception Hierarchy
5

6
### Base Exceptions
7

8
```python { .api }
9
class EcCodesError(Exception):
10
    """Base exception for all ecCodes errors."""
11

12
class GribInternalError(EcCodesError):
13
    """Internal error in GRIB processing."""
14

15
class BufferTooSmallError(EcCodesError):
16
    """Buffer size insufficient for operation."""
17
```
18

19
### File and I/O Errors
20

21
```python { .api }
22
class FileNotFoundError(EcCodesError):
23
    """File not found or cannot be opened."""
24

25
class IOProblemError(EcCodesError):
26
    """Input/output operation failed."""
27

28
class InvalidFileError(EcCodesError):
29
    """File format is invalid or corrupted."""
30

31
class PrematureEndOfFileError(EcCodesError):
32
    """Unexpected end of file encountered."""
33
```
34

35
### Data Access Errors
36

37
```python { .api }
38
class KeyValueNotFoundError(EcCodesError):
39
    """Requested key not found in message."""
40

41
class InvalidKeyValueError(EcCodesError):
42
    """Key value is invalid or out of range."""
43

44
class ReadOnlyError(EcCodesError):
45
    """Attempted to modify read-only key."""
46

47
class WrongArraySizeError(EcCodesError):
48
    """Array size mismatch in operation."""
49
```
50

51
### Message Processing Errors
52

53
```python { .api }
54
class InvalidMessageError(EcCodesError):
55
    """Message format is invalid."""
56

57
class DecodingError(EcCodesError):
58
    """Error decoding message data."""
59

60
class EncodingError(EcCodesError):
61
    """Error encoding message data."""
62

63
class UnsupportedEditionError(EcCodesError):
64
    """Unsupported GRIB/BUFR edition."""
65
```
66

67
### Memory and Resource Errors
68

69
```python { .api }
70
class OutOfMemoryError(EcCodesError):
71
    """Insufficient memory for operation."""
72

73
class NullHandleError(EcCodesError):
74
    """Invalid or null message handle."""
75

76
class InvalidArgumentError(EcCodesError):
77
    """Invalid argument passed to function."""
78
```
79

80
## Usage Examples
81

82
### Robust File Processing
83

84
```python
85
import eccodes
86
from eccodes import EcCodesError, FileNotFoundError, KeyValueNotFoundError
87

88
def safe_read_grib(filename):
89
    try:
90
        with open(filename, 'rb') as f:
91
            msg = eccodes.codes_grib_new_from_file(f)
92
            if msg is None:
93
                print("No messages found in file")
94
                return None
95
            
96
            # Safe key access
97
            try:
98
                param_id = eccodes.codes_get(msg, 'paramId')
99
                level = eccodes.codes_get(msg, 'level')
100
                print(f"Parameter {param_id} at level {level}")
101
            except KeyValueNotFoundError as e:
102
                print(f"Key not found: {e}")
103
            
104
            eccodes.codes_release(msg)
105
            
106
    except FileNotFoundError:
107
        print(f"File not found: {filename}")
108
    except InvalidFileError:
109
        print(f"Invalid file format: {filename}")
110
    except EcCodesError as e:
111
        print(f"ecCodes error: {e}")
112

113
# Usage
114
safe_read_grib('forecast.grib')
115
```