DOCSP-41135: Specify Fields #8
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source/read/project.txt
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| You can use a projection to specify which fields to include in a return | ||
| document, or to specify which fields to exclude. You cannot combine inclusion and |
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Q: I'm unclear on whether "You cannot combine inclusion and exclusion statements..." means that I can combine both only if I am excluding the _id field and nothing else (in my exclusion statement), or if I can combine both if I have an exclusion statement that excludes the _id field as well as excluding other fields.
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C: Ok, reading further I now understand that the exclusion statement only applies to _id. You could potentially make that clearer earlier in the document.
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C: This also confuses me because it seems like, based on my understanding, the only time you'd combine includes and excludes statements is to exclude the _id field, as all other fields are implicitly excluded when you use a includes statement? Could you clarify when someone would want to use both an includes and excludes that didn't just exclude _id?
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The idea is that a standard query will pull all the document's fields, and once you apply a projection to specify the inclusion of a single field, all other fields automatically get excluded (except "_id").
Someone shouldn't want to use both an includes and excludes. I can try addressing this confusion by pulling up the clarifying text from below the page into this mention up here.
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yeah, I think moving the clarifying text up would be good.
source/read/project.txt
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| .. code-block:: kotlin | ||
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| val projection = Projection.fields( | ||
| Projections.include(<fieldName1>, <fieldName2>, ...), |
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Q: is there supposed to be a comma at the end of this line?
| Projections.include(<fieldName1>, <fieldName2>, ...), | |
| Projections.include(<fieldName1>, <fieldName2>, ...) |
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Good catch, can remove
source/read/project.txt
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| When specifying fields to include, you can also exclude the ``_id`` field from | ||
| the returned document. | ||
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| The following example performs the same query as the preceding example, but |
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| The following example performs the same query as the preceding example, but | |
| The following example runs the same query as the preceding example, but |
| Exclude the ``_id`` Field | ||
| ~~~~~~~~~~~~~~~~~~~~~~~~~ | ||
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| When specifying fields to include, you can also exclude the ``_id`` field from |
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Q: Can you only exclude the _id field when specifying fields to include, or can you exclude just the _id field without using any includes statements?
mcmorisi
requested review from
a team and
vbabanin
and removed request for
a team
(cherry picked from commit 53751bb)
(cherry picked from commit 53751bb)
Pull Request Info
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JIRA - https://jira.mongodb.org/browse/DOCSP-41135
Staging - https://preview-mongodbmcmorisi.gatsbyjs.io/kotlin-sync/DOCSP-41135-specify-fields/read/project
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