0
# Schema and Field Types
1

2
Schema definition and validation system for specifying the structure of geospatial data, including field types, geometry types, and validation rules.
3

4
## Capabilities
5

6
### Schema Utility Functions
7

8
```python { .api }
9
def prop_type(text):
10
    """
11
    Returns a schema property's proper Python type.
12
    
13
    Parameters:
14
    - text: str, type name with or without width
15
    
16
    Returns:
17
    type: Python class (int, str, float, etc.)
18
    """
19

20
def prop_width(val):
21
    """
22
    Returns the width of a str type property.
23
    
24
    Parameters:
25
    - val: str, type:width string from schema
26
    
27
    Returns:
28
    int or None: Width for string types, None for others
29
    """
30
```
31

32
### Field Type Classes
33

34
Fiona supports various field types for representing different kinds of attribute data:
35

36
- **FionaIntegerType**: 32-bit integers
37
- **FionaInt16Type**: 16-bit integers  
38
- **FionaBooleanType**: Boolean values
39
- **FionaInteger64Type**: 64-bit integers
40
- **FionaRealType**: Floating point numbers
41
- **FionaStringType**: String values
42
- **FionaBinaryType**: Binary data
43
- **FionaStringListType**: Lists of strings
44
- **FionaJSONType**: JSON data
45
- **FionaDateType**: Date values
46
- **FionaTimeType**: Time values
47
- **FionaDateTimeType**: DateTime values
48

49
#### Usage Examples
50

51
```python
52
from fiona import prop_type, prop_width
53

54
# Get Python type from schema string
55
int_type = prop_type('int')        # <class 'int'>
56
str_type = prop_type('str:50')     # <class 'str'>
57
float_type = prop_type('float')    # <class 'float'>
58

59
# Get string field width
60
width = prop_width('str:25')       # 25
61
default_width = prop_width('str')  # 80
62
non_str_width = prop_width('int')  # None
63

64
# Schema definition example
65
schema = {
66
    'geometry': 'Point',
67
    'properties': {
68
        'name': 'str:50',      # String with max 50 characters
69
        'population': 'int',    # Integer
70
        'area': 'float',       # Float
71
        'active': 'bool',      # Boolean
72
        'founded': 'date',     # Date
73
        'metadata': 'json'     # JSON data
74
    }
75
}
76
```