String 如何将列表（从Collect）转换为字符串

使用CYPHER，我可以使用collect（）函数获得事物的有序列表。是否可以将这样一个列表转换为一个简单的字符串，使其作为单个字符串对象

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如果这不可能，是否可以以某种方式将两个（或多个）collect语句的内容顺序连接起来，以便在一行中生成诸如“a，B，ca，B，C”之类的输出，其中a，B，C是第一个collect语句的有序积，a，B，C是第二个collect语句的有序积，您需要合并集合，然后使用

REDUCE（）

将每个项附加到字符串中。像这样：

WITH COLLECT(first_group) AS a, COLLECT(second_group) AS b
WITH a + b AS c
WITH REDUCE(s = HEAD(c), n IN TAIL(c) | s + ', ' + n) AS result
RETURN result

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查看

REDUCE

，更好地了解它在Cypher中的工作原理。

一个更通用的解决方案也适用于对象集合（不仅仅是字符串集合），即使用以下过程将串联的集合转换为字符串化JSON

此示例使用字符串集合：

WITH ['A','B','C'] AS x, ['a','b','c'] AS y, ['do','re','mi'] AS z
WITH x + y + z AS data
CALL apoc.convert.toJson(data) YIELD value
RETURN value

WITH [{a:1},{b:2},{c:3}] AS x, [{a:10},{b:20},{c:30}] AS y, [{a:100},{b:200},{c:300}] AS z
WITH x + y + z AS data
CALL apoc.convert.toJson(data) YIELD value
RETURN value

将返回此文件：

"[\"A\",\"B\",\"C\",\"a\",\"b\",\"c\",\"do\",\"re\",\"mi\"]"

"[{\"a\":1},{\"b\":2},{\"c\":3},{\"a\":10},{\"b\":20},{\"c\":30},{\"a\":100},{\"b\":200},{\"c\":300}]"

此示例使用对象集合：

WITH ['A','B','C'] AS x, ['a','b','c'] AS y, ['do','re','mi'] AS z
WITH x + y + z AS data
CALL apoc.convert.toJson(data) YIELD value
RETURN value

WITH [{a:1},{b:2},{c:3}] AS x, [{a:10},{b:20},{c:30}] AS y, [{a:100},{b:200},{c:300}] AS z
WITH x + y + z AS data
CALL apoc.convert.toJson(data) YIELD value
RETURN value

将返回此文件：

"[\"A\",\"B\",\"C\",\"a\",\"b\",\"c\",\"do\",\"re\",\"mi\"]"

"[{\"a\":1},{\"b\":2},{\"c\":3},{\"a\":10},{\"b\":20},{\"c\":30},{\"a\":100},{\"b\":200},{\"c\":300}]"

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我认为您应该检查cypher中的reduce（）函数。