42 lines
1.4 KiB
Plaintext
42 lines
1.4 KiB
Plaintext
:sig
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s64 DValue::to_s64(s64 default_value = 0) const
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:params
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default_value : returned when the value is missing or cannot be parsed as a number
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return value : the value as a signed 64-bit integer, or `default_value`
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:see
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>types
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0_DValue
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to_u64
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to_f64
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to_bool
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to_string
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:content
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Reads a `DValue` value as a signed integer. This is a read accessor: it is `const`, never creates or modifies nodes, and dereferences internal references automatically.
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String values are trimmed and parsed permissively: plain integers, floating-point forms (truncated toward zero), and the boolean words understood by `to_bool()` (`yes` reads as `1`) all convert. Results outside the `s64` range clamp to the range boundaries. Boolean values become `1` or `0`.
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`default_value` is returned when:
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- the node is unset or holds an empty string
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- the string does not parse as a number (`"not-a-number"`)
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- the node is map-shaped with more than one entry, or an unresolvable reference
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A map-shaped node with exactly one entry unwraps to that entry's value before converting — this matches how single-value rows from query results read.
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## Example
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```cpp
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s64 page = context.get["page"].to_s64(1);
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s64 limit = context.cfg.get_by_path("app/page_size").to_s64(25);
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```
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`json_decode()` stores JSON numbers as string-valued nodes, so this is the normal way to consume decoded numeric fields.
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## Related Concepts
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- PHP: `intval()` with a fallback
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- JavaScript: `parseInt(x) || fallback`
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