Missing Object Member Default Filler
Fill only absent own JSON members from defaults; existing null, false, zero and empty strings are preserved.
Description
Fill only absent own JSON members from defaults; existing null, false, zero and empty strings are preserved.
Default filling supplies values only for absent object members. An explicit null or zero can be a deliberate value that should survive the merge.
When to use this tool
Fill only absent own JSON members from defaults; existing null, false, zero and empty strings are preserved.
- Prepare the supplied objectJson, defaultsJson fields for this operation.
- Compare the complete example with the representation used by your own input before carrying the result into another step.
How to use the tool and how it works
- Enter objectJson, defaultsJson. Use the exact text syntax, units and index conventions explained below.
- Run the tool. If input validation fails, correct the supplied fields before interpreting any result.
- Read result.object, result.filledKeys. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.
Decode the object and defaults as objects. Keep every original entry, append default entries whose keys are not own properties of the original, and return filledKeys.1
| Input field | Meaning and representation | Accepted input |
|---|---|---|
| objectJson | JSON text, entered as one text field. The decoded structure is illustrated below; it is not a separate file. | Text |
| defaultsJson | JSON text, entered as one text field. The decoded structure is illustrated below; it is not a separate file. | Text |
For the JSON text fields, the following decoded structures show the example records before they are serialized into input strings. Keep field names, list nesting and value types as shown.
[
{
"field": "objectJson",
"decoded": {
"a": null
}
},
{
"field": "defaultsJson",
"decoded": {
"a": 1,
"b": 2
}
}
]| Output field | Interpretation |
|---|---|
| result | Object containing the named outputs below. |
| result.object | The object value under the stated formula or text convention. |
| result.filledKeys | The filled keys list in the ordering and representation described above. |
{
"input": {
"objectJson": "{\"a\":null}",
"defaultsJson": "{\"a\":1,\"b\":2}"
},
"output": {
"result": {
"object": {
"a": null,
"b": 2
},
"filledKeys": [
"b"
]
}
}
}Limitations and assumptions
- The merge is shallow and does not replace existing null values or recursively fill nested objects. Defaults are supplied data rather than validated application settings.
- Decoded JSON is bounded to 20,000 nodes and 32 nesting levels; record arrays have at most 128 records. Parsed number values use JavaScript floating point rather than arbitrary-precision decimal arithmetic.
- Every declared top-level field is required and unexpected fields are rejected. Numeric inputs must be finite; ordinary text fields are bounded to 8,192 UTF-16 code units, with tighter operation-specific limits where stated.
- Ordinary string lists have at most 128 entries of at most 128 code units each; numeric lists and matrices have separate bounded size checks. Nonfinite results and excessively large serialized outputs are rejected.
- Indexes are zero-based and spans have an exclusive end unless explicitly stated otherwise. A valid false, null or empty-list result is distinct from malformed input.
Alternative or Complementary methods
For document-wide requirements, combine these structural inventories with an explicit JSON Schema. Preserve the distinction between missing properties and null values, and between numbers and numeric-looking strings when building joins or indexes.
References
Similar or alternative tools
- Object Key Prefix Partitioner
Partition own JSON object members by exact literal key prefix; does not strip prefixes or interpret patterns.
- Object Key Rename Map
Simultaneously rename own JSON object keys from an explicit map; reject collisions with renamed or untouched keys.