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51 lines
1.3 KiB
Markdown
51 lines
1.3 KiB
Markdown
# Find All Objects In An Array Where Key Is Set
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Let's say we have a large array of objects. And the data in those objects,
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while generally having the same shape, does not always have certain values set.
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For instance, here is some data where the `token` is sometimes set, sometimes
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`null`, and sometimes missing altogether.
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```json
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[
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{
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"id": 1,
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"token": "abc"
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},
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{
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"id": 3,
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"token": null
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},
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{
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"id": 5
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},
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...
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]
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```
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We can find out how many objects in this collection have the `token` key set to
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an actual value with [a `jq` query](https://stedolan.github.io/jq/manual) like
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the following.
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```bash
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jq '. | map(select(has("token") and .token != null)) | length' data.json
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```
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This maps over each object selecting those where it has `token` and `token` is
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not `null`.
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We can instead produce the inverse count—those objects where `token` is not set
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to a value—with the `not` operator.
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```bash
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jq '. | map(select(has("token") and .token != null | not)) | length' data.json
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```
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If you want to inspect the array of objects that either of these queries filters down to, you can drop the `| length` part.
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```bash
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jq '. | map(select(has("token") and .token != null))' data.json
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```
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Here is [a live example](https://jqterm.com/?query=.%20%7C%20map%28select%28has%28%22token%22%29%20and%20.token%20!%3D%20null%20%7C%20not%29%29).
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