Random Nested JSON Document Generator

Description

Generate exact-count nested object/contiguous-array JSON documents from bounded dot-path primitive templates and delegate unflattening/pretty printing; reject leaf conflicts, sparse arrays and inherited-property segments before calling the existing core.

A parser corpus pairs literal input spellings or structured documents with observable parser results or explicitly constructed expectations. Successful parsing, semantic validity, and exact round-trip preservation are separate properties, so test records retain the relevant evidence.

When to use this tool

Use this generator to create reproducible nested json document cases from the supplied model or bank. Inspect the returned evidence before using cases in a test or exercise.

How to use the tool and how it works

Supply documentCount, fields, indent in the field shapes below. Set seed when you need an explicit replay.
Run the tool and correct any input error. For generated controls, distinguish a successful fixture containing an invalid case from failure to generate the fixture.
Read documents. Use the conventions below and keep answer-bearing fields separate when presenting an exercise.

Validate the supplied document field specifications, generate each structured document from those fields, and serialize with the requested indentation. Enforce aggregate field-work and serialized-output budgets.^[1]

Input field	Meaning and units	Accepted input
documentCount	Document Count	Required. Safe integer; minimum 1; maximum 64.
fields	Fields	Required. Array of Object; no unknown keys. or Object; no unknown keys. or Object; no unknown keys. or Object; no unknown keys.; minimum items 1; maximum items 64.
indent	Indent	Required. Safe integer; minimum 1; maximum 8.
seed	Optional numeric seed; takes precedence over context randomness. Without either, use the fixed tool.io default seed.	Optional. Safe integer.

Output field	Interpretation	Returned shape
documents	Documents	Required. Array of Object; no unknown keys.; minimum items 1; maximum items 64.
documents[].flatFields	Flat Fields	Required. Object.
documents[].document	Document	Required. Object.
documents[].pretty	Pretty	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 1000000.
randomness	Replay metadata: source is seed or context; seed is the normalized 32-bit seed or null for a context source.	Required. Object; no unknown keys.
randomness.seed	Optional numeric replay seed; normalization and precedence are explained below.	Required. Safe integer. or Null.
randomness.source	Source	Required. Text; one of "context", "seed".

An explicit safe-integer seed takes precedence over injected context randomness and is normalized to an unsigned 32-bit integer. With no seed and no context source, replay uses the fixed tool.io default seed. A context source must return finite values from zero inclusive to one exclusive; its advancing state must be retained separately. randomness records the source and normalized seed, or null for context. These generators are not cryptographic random sources.

json

{
  "input": {
    "documentCount": 2,
    "fields": [
      {
        "key": "profile.name",
        "kind": "text",
        "choices": [
          "Ada",
          "Grace"
        ]
      },
      {
        "key": "scores.0",
        "kind": "integer",
        "minimum": 1,
        "maximum": 5
      },
      {
        "key": "scores.1",
        "kind": "integer",
        "minimum": 1,
        "maximum": 5
      }
    ],
    "indent": 2,
    "seed": 42
  },
  "output": {
    "documents": [
      {
        "flatFields": {
          "profile.name": "Grace",
          "scores.0": 3,
          "scores.1": 5
        },
        "document": {
          "profile": {
            "name": "Grace"
          },
          "scores": [
            3,
            5
          ]
        },
        "pretty": "{\n  \"profile\": {\n    \"name\": \"Grace\"\n  },\n  \"scores\": [\n    3,\n    5\n  ]\n}\n"
      },
      {
        "flatFields": {
          "profile.name": "Grace",
          "scores.0": 1,
          "scores.1": 3
        },
        "document": {
          "profile": {
            "name": "Grace"
          },
          "scores": [
            1,
            3
          ]
        },
        "pretty": "{\n  \"profile\": {\n    \"name\": \"Grace\"\n  },\n  \"scores\": [\n    1,\n    3\n  ]\n}\n"
      }
    ],
    "randomness": {
      "seed": 42,
      "source": "seed"
    }
  }
}

Limitations and assumptions

The structure follows the supplied field grammar rather than an arbitrary executable JSON Schema. Generated data is synthetic; consumers should use returned serialized and decoded forms under their respective contracts.
A replay requires the same complete input and implementation. Randomized construction does not guarantee uniform coverage of every feasible output; finite samples can repeat unless a distinct-selection rule is explicitly stated.
The field tables state structural bounds; cross-field constraints and bounded search or output budgets also apply. Unknown keys are rejected where the object contract disallows them. Input errors are distinct from null fields and deliberate invalid controls in a successful output.

Alternative or Complementary methods

For a supplied example, inspect the returned construction or delegated check directly. To evaluate a consumer, also test cases chosen for its own boundaries; a generated finite corpus does not establish exhaustive coverage.

References

Tool behavior and example: Random Nested JSON Document Generator — tool.io

Similar or alternative tools

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Random JSON Flattening Round-Trip Corpus Generator
Reuse the random nested-document generator for its safe dot-path/contiguous-array subset, then actually flatten and rebuild every generated document with both existing cores; retain intermediate leaves and original/rebuilt forms, excluding sparse/mixed containers, reserved segments, literal-dot keys and empty-container loss cases rather than claiming arbitrary JSON round trips.