如何编写jq表达式将嵌套数组JSON转为JSON Schema并修复类型错误

原始JSON结构：

{"objectSchema": {"fields": [{"name": "OBJECTID","type": "esriFieldTypeOID","alias": "OBJECTID","domain": null,"editable": false,"nullable": false,"defaultValue": null,"modelName": "OBJECTID"},{"name": "ENABLED","type": "esriFieldTypeSmallInteger","alias": "ENABLED","domain": {"type": "codedValue","name": "EnabledDomain","description": "Geometric Network Enabled domain","codedValues": [{"name": "False","code": 0},{"name": "True","code": 1}],"mergePolicy": "esriMPTDefaultValue","splitPolicy": "esriSPTDefaultValue"},"editable": true,"nullable": true,"defaultValue": 1,"modelName": "ENABLED"},{"name": "GLOBALID","type": "esriFieldTypeGlobalID","alias": "GLOBALID","domain": null,"editable": false,"nullable": false,"length": 38,"defaultValue": null,"modelName": "GLOBALID"}]}}

原使用的jq表达式：

def convertToSchema: if type == "array" then if length == 0 then {"type": "array", "items": {"type": "string"}} else {"type": "array", "items": (reduce map(convertToSchema)[] as $i ({}; . *= $i))} end elif type == "object" then {"type": "object", "properties": map_values(convertToSchema)} elif type == "boolean" then {"type": "boolean"} elif type == "number" then {"type": "number"} elif type == "string" then {"type": "string"} elif type == "null" then {"type": "string"} else {"type": (type | tostring)} end; .objectSchema | convertToSchema

当前问题：转换后的JSON Schema中，domain字段的类型被错误识别为string，但实际上该字段既可以是null也可以是object，需要修正表达式以正确处理嵌套对象、null值，并合并数组所有项的唯一属性生成正确的Schema。

def mergeSchemas($a; $b):
  if $a == {} then $b
  elif $b == {} then $a
  else
    .type = (
      if ($a.type | type) == "array" and ($b.type | type) == "array" then ($a.type + $b.type | unique)
      elif ($a.type | type) == "array" then ($a.type + [$b.type] | unique)
      elif ($b.type | type) == "array" then ($b.type + [$a.type] | unique)
      elif $a.type != $b.type then [$a.type, $b.type]
      else $a.type
    )
    | if ($a | has("properties")) and ($b | has("properties")) then
        .properties = ($a.properties + $b.properties | with_entries(.value = mergeSchemas($a.properties[.key]; $b.properties[.key])))
      elif ($a | has("properties")) then .properties = $a.properties
      elif ($b | has("properties")) then .properties = $b.properties
      else . end
    | if ($a | has("items")) and ($b | has("items")) then
        .items = mergeSchemas($a.items; $b.items)
      elif ($a | has("items")) then .items = $a.items
      elif ($b | has("items")) then .items = $b.items
      else . end
  end;

def convertToSchema:
  if type == "array" then
    if length == 0 then {"type": "array", "items": {"type": "string"}}
    else
      {"type": "array", "items": (reduce map(convertToSchema)[] as $item ({}; mergeSchemas(.; $item)))}
    end
  elif type == "object" then
    {"type": "object", "properties": map_values(convertToSchema)}
  elif type == "boolean" then {"type": "boolean"}
  elif type == "number" then {"type": "number"}
  elif type == "string" then {"type": "string"}
  elif type == "null" then {"type": "null"}
  else {"type": (type | tostring)}
  end;

.objectSchema | convertToSchema

1. 修正null值处理：将原表达式中elif type == "null" then {"type": "string"}改为{"type": "null"}，保留null类型的正确标识。
2. 新增Schema合并逻辑：定义mergeSchemas函数，用于合并数组中多个项的Schema：
   • 处理类型合并：当两个Schema类型不同时，将类型合并为数组形式（如["object", "null"]）
   • 递归合并嵌套属性：对于object类型的properties和array类型的items，递归调用合并逻辑，确保嵌套结构正确合并
3. 数组项合并优化：使用自定义的mergeSchemas替代原有的.*= $i，确保数组中所有项的属性被正确合并为包含所有可能类型的Schema

{
  "type": "object",
  "properties": {
    "fields": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "name": {
            "type": "string"
          },
          "type": {
            "type": "string"
          },
          "alias": {
            "type": "string"
          },
          "domain": {
            "type": [
              "null",
              "object"
            ],
            "properties": {
              "type": {
                "type": "string"
              },
              "name": {
                "type": "string"
              },
              "description": {
                "type": "string"
              },
              "codedValues": {
                "type": "array",
                "items": {
                  "type": "object",
                  "properties": {
                    "name": {
                      "type": "string"
                    },
                    "code": {
                      "type": "number"
                    }
                  }
                }
              },
              "mergePolicy": {
                "type": "string"
              },
              "splitPolicy": {
                "type": "string"
              }
            }
          },
          "editable": {
            "type": "boolean"
          },
          "nullable": {
            "type": "boolean"
          },
          "defaultValue": {
            "type": [
              "null",
              "number"
            ]
          },
          "modelName": {
            "type": "string"
          },
          "length": {
            "type": [
              "null",
              "number"
            ]
          }
        }
      }
    }
  }
}

内容的提问来源于stack exchange，提问作者sujay777