从Datomic实体获取所有字段 [英] Get all fields from a Datomic entity
问题描述
Datomic查询和规则文档的嵌入部分说明：
像SQL这样的查询语言是围绕客户机 - 服务器模型
定位的，在单个会话中，您必须同时具有：
- 回答你的基本问题，例如
- 恢复报告和处理所需的任何其他信息，例如：他们的姓名和电子邮件地址是什么。
后者不是真正的查询，它只是一个机械导航
相关信息。
虽然我明白两个不同方面的正交性如何，我认为我经常需要检索
据我所知，查询通常具有以下格式：
<$> p $ p>
（datomic.api / q'[：find？name？age？email
：where
[？e：myapp / name？name]
[？e：myapp / age？age]
[？e：myapp / email？email]]
（db conn））
如果我想检索具有N个属性的实体，我会让他们在每个查询中列出它们，这看起来很乏味，容易出错。
如何告诉Datomic检索带有它们持久化的所有字段的实体，而无需明确指定它们？
$ b $.api / entity 提供了这样的功能。
它只是有getcha的返回地图有一个自定义的表示， code>：db / id 。可以访问这些字段，但打印它们需要将地图合并到常规Clojure地图中。
The 'Embedded' section of the Datomic Queries and Rules document says:
Query languages like SQL are oriented around a client-server model where, in a single conversaton, you are going to have to both:
- Answer your fundamental question, e.g. who bought socks this month.
- Recover any additional information required for reporting and processing, e.g. what are their names and email addresses.
The latter is not really a query, it is just a mechanical navigation to related information.
While I appreciate how the orthogonality of the two different mentioned aspects is honored, I think I'll often need to retrieve a whole entity, whichever its attributes are.
As far as I know, queries typically have this form:
(datomic.api/q '[:find ?name ?age ?email
:where
[?e :myapp/name ?name]
[?e :myapp/age ?age]
[?e :myapp/email ?email]]
(db conn))
If I wanted to retrieve entities that have N attributes, I'd have them to list them all in each query, which seems tedious and error-prone to me.
How to tell Datomic to retrieve the entities with all the fields they were persisted with, without having to specify them explicitly?
datomic.api/entity provides such functionality.
It just has the gotcha that the returned map has a custom representation which hides all fields but :db/id. One can access those fields, but printing them requires merging the map into a regular Clojure map.
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