Add Date aggregation #1585

Stefan-Stojanovic · 2019-10-25T14:31:07Z

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enki-hq · 2019-10-25T14:31:25Z

Insight previews:

enki-hq · 2019-11-01T14:34:09Z

Rule workout:insights failed for files:

mongodb/intro/date-aggregation/README.md

mongodb/intro/date-aggregation/README.md

mongodb/intro/date-aggregation/aggregation-with-date-expression-operators.md

mongodb/intro/date-aggregation/aggregation-with-date-expression-operators-ii.md

mongodb/intro/date-aggregation/aggregation-with-date-expression-operators-v.md

Co-Authored-By: Andrei Calabangiu <andrei@enki.com>

…n-operators.md Co-Authored-By: Andrei Calabangiu <andrei@enki.com>

kapnobatai137 · 2020-01-08T08:36:55Z

test in spider
merge

kapnobatai137 · 2020-10-13T09:02:58Z

mongodb/intro/date-aggregation/aggregation-with-date-expression-operators-ii.md

+
+Now that we know how to extract the date into an ISODate format, we can use some aggregation operators to find the exact time that the document was made as precise as in milliseconds.
+
+**Note:** For easier readability and comprehension of date operators, we will be using the date from the `name:"Bulbasaur"` document shown in the previous insight. **(The document will also be in the footnotes of every insight of this workout under Previous Document[1])**


Suggested change

**Note:** For easier readability and comprehension of date operators, we will be using the date from the `name:"Bulbasaur"` document shown in the previous insight. **(The document will also be in the footnotes of every insight of this workout under Previous Document[1])**

> 💡 For easier readability and comprehension of date operators, we will be using the date from the `name: "Bulbasaur"` document shown in the previous insight. **(The document will also be in the footnotes of every insight of this workout under Previous Document[1])**

kapnobatai137 · 2020-10-13T09:03:28Z

mongodb/intro/date-aggregation/aggregation-with-date-expression-operators-ii.md

+
+**Note:** For easier readability and comprehension of date operators, we will be using the date from the `name:"Bulbasaur"` document shown in the previous insight. **(The document will also be in the footnotes of every insight of this workout under Previous Document[1])**
+
+**Note:** All 10 date operators have the same syntax:


Suggested change

**Note:** All 10 date operators have the same syntax:

All date operators have the same syntax:

kapnobatai137 · 2020-10-13T09:04:41Z

mongodb/intro/date-aggregation/aggregation-with-date-expression-operators-ii.md

+
+The `$year` operator is used to find the year the document was created.
+
+Since we are only looking for the date of a specific document, we will use the `$match` stage to only match the document we want. Also, we will use the `$project` stage to only aggregate the parts of the date we want.


I'm not sure "aggregate" is the right word here. how does this sound?

Suggested change

Since we are only looking for the date of a specific document, we will use the `$match` stage to only match the document we want. Also, we will use the `$project` stage to only aggregate the parts of the date we want.

Since we are only looking for the date of a specific document, we will use the `$match` stage to only match the document we want. We'll use the `$project` stage to display only the parts of the date we want.

kapnobatai137 · 2020-10-13T09:07:15Z

mongodb/intro/date-aggregation/aggregation-with-date-expression-operators-ii.md

+}
+```
+
+As you can see in the example above, the `$match` stage was used to match the pokémon document named `"Bulbasaur"` and get the year it was created.


how does this sound?

Suggested change

As you can see in the example above, the `$match` stage was used to match the pokémon document named `"Bulbasaur"` and get the year it was created.

We use the `$match` to find the pokémon document named `"Bulbasaur"`. Then, we extract the creation year in the `project` stage.

kapnobatai137 · 2020-10-13T09:07:30Z

mongodb/intro/date-aggregation/aggregation-with-date-expression-operators-ii.md

+
+The "createdAt" in `createdAtYear: { $year: "$createdAt" }` is just how we named our date field after we extracted the date with the `.getTimestamp()` method.
+
+**Note:** Just like with any aggregation, if we don't exclude the `_id` with the project stage, it will be displayed by default.


Suggested change

**Note:** Just like with any aggregation, if we don't exclude the `_id` with the project stage, it will be displayed by default.

> 💡 Just like with any aggregation, if we don't exclude the `_id` with the project stage, it will be displayed by default.

kapnobatai137 · 2020-10-13T09:37:50Z

mongodb/intro/date-aggregation/aggregation-with-date-expression-operators-v.md

+
+Now that we've seen all the date operators and know how to use them, let's take a look at an example of all operators being used in the same aggregation.
+
+**Note:** We are using the same document[1] as in the previous insights.


Suggested change

**Note:** We are using the same document[1] as in the previous insights.

> 💡 We are using the same document[1] as in the previous insights.

kapnobatai137 · 2020-10-13T09:40:38Z

mongodb/intro/date-aggregation/aggregation-with-date-expression-operators-v.md

+Example with all operators:
+```js
+db.pokemon.aggregate([
+  { $match: { name: "Bulbasaur" } },
+  {
+    $project: {
+      dayOfTheYear: { $dayOfYear: "$createdAt" },
+      createdAtYear: { $year: "$createdAt" },
+      createdAtMonth: { $month: "$createdAt" },
+      dayOfTheMonth: { $dayOfMonth: "$createdAt" },
+      createdAtHour: { $hour: "$createdAt" },
+      createdAtMinute: { $minute: "$createdAt" },
+      createdAtSecond: { $second: "$createdAt" },
+      createdAtMillisecond: { $millisecond: "$createdAt" },
+      weekOfTheYear: { $week: "$createdAt" },
+      dayOfTheWeek: { $dayOfWeek: "$createdAt" },
+      _id: 0
+    }
+  }
+]);
+```
+
+Output:
+```js
+{ 
+  "dayOfTheYear": 282, 
+  "createdAtYear": 2019, 
+  "createdAtMonth": 10, 
+  "dayOfTheMonth": 9, 
+  "createdAtHour": 7, 
+  "createdAtMinute": 21, 
+  "createdAtSecond": 14, 
+  "createdAtMillisecond": 0, 
+  "weekOfTheYear": 40, 
+  "dayOfTheWeek": 4 
+}
+```


can we use a more creative example? imo there is no benefit in this example because we've already shown this in all the previous insights. all that it does is add all the operators in the project stage

we could do something like finding the remaining time until one's birthday, the number of days remaining untill a contract renewal or something else. also, we don't have to include all the operators as long as we use an example that shows how a user could use these operators in a real-life application

edit: I notice that you give some examples in the first insight. why not make use of those? "These operators can be used to extract the specific time at which a document was made, they can be used to find a group of documents created on a specific date or to find all documents between 2 dates."

kapnobatai137 · 2020-10-13T09:41:08Z

mongodb/intro/date-aggregation/aggregation-with-date-expression-operators-v.md

+```
+
+---
+## Practice


we should add a revision question for this as well

kapnobatai137 · 2020-10-13T09:41:59Z

mongodb/intro/date-aggregation/aggregation-with-date-expression-operators.md

+---
+## Content
+
+In MongoDB, it is possible to aggregate a collection using date expression operators. These operators can be used to extract the specific time at which a document was made, they can be used to find a group of documents created on a specific date or to find all documents between 2 dates.


Suggested change

In MongoDB, it is possible to aggregate a collection using date expression operators. These operators can be used to extract the specific time at which a document was made, they can be used to find a group of documents created on a specific date or to find all documents between 2 dates.

In MongoDB, it is possible to aggregate a collection using date expression operators.

These operators can be used to extract the specific time at which a document was made, find a group of documents created on a specific date, or to find all documents between two dates.

kapnobatai137 · 2020-10-13T09:43:05Z

mongodb/intro/date-aggregation/aggregation-with-date-expression-operators.md

+There are a total of 10 operators that can be used to aggregate a collection by date.
+
+These are:
+- `$year`
+- `$month`
+- `$dayOfMonth`
+- `$week`
+- `$hour`
+- `$minute`
+- `$second`
+- `$milisecond`
+- `$dayOfYear`
+- `$dayOfWeek`


Suggested change

There are a total of 10 operators that can be used to aggregate a collection by date.

These are:

- `$year`

- `$month`

- `$dayOfMonth`

- `$week`

- `$hour`

- `$minute`

- `$second`

- `$milisecond`

- `$dayOfYear`

- `$dayOfWeek`

There are a total of 10 operators that can be used to aggregate a collection by date:

- `$year`

- `$month`

- `$dayOfMonth`

- `$week`

- `$hour`

- `$minute`

- `$second`

- `$milisecond`

- `$dayOfYear`

- `$dayOfWeek`

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Stefan-Stojanovic changed the title ~~Add Date aggregation {wip}~~ Add Date aggregation Nov 1, 2019

Stefan-Stojanovic added the awaiting review label Nov 1, 2019

kapnobatai137 reviewed Nov 7, 2019

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Co-Authored-By: Andrei Calabangiu <andrei@enki.com>

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…n-operators.md Co-Authored-By: Andrei Calabangiu <andrei@enki.com>

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Add Date aggregation #1585

Add Date aggregation #1585

Stefan-Stojanovic commented Oct 25, 2019

enki-hq commented Oct 25, 2019 •

edited

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kapnobatai137 Oct 13, 2020

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		Now that we know how to extract the date into an ISODate format, we can use some aggregation operators to find the exact time that the document was made as precise as in milliseconds.

		Note: For easier readability and comprehension of date operators, we will be using the date from the `name:"Bulbasaur"` document shown in the previous insight. (The document will also be in the footnotes of every insight of this workout under Previous Document[1])

	Note: For easier readability and comprehension of date operators, we will be using the date from the `name:"Bulbasaur"` document shown in the previous insight. (The document will also be in the footnotes of every insight of this workout under Previous Document[1])
	> 💡 For easier readability and comprehension of date operators, we will be using the date from the `name: "Bulbasaur"` document shown in the previous insight. (The document will also be in the footnotes of every insight of this workout under Previous Document[1])


		Note: For easier readability and comprehension of date operators, we will be using the date from the `name:"Bulbasaur"` document shown in the previous insight. (The document will also be in the footnotes of every insight of this workout under Previous Document[1])

		Note: All 10 date operators have the same syntax:

	Note: All 10 date operators have the same syntax:
	All date operators have the same syntax:


		The `$year` operator is used to find the year the document was created.

		Since we are only looking for the date of a specific document, we will use the `$match` stage to only match the document we want. Also, we will use the `$project` stage to only aggregate the parts of the date we want.

	As you can see in the example above, the `$match` stage was used to match the pokémon document named `"Bulbasaur"` and get the year it was created.
	We use the `$match` to find the pokémon document named `"Bulbasaur"`. Then, we extract the creation year in the `project` stage.


		The "createdAt" in `createdAtYear: { $year: "$createdAt" }` is just how we named our date field after we extracted the date with the `.getTimestamp()` method.

		Note: Just like with any aggregation, if we don't exclude the `_id` with the project stage, it will be displayed by default.

	Note: Just like with any aggregation, if we don't exclude the `_id` with the project stage, it will be displayed by default.
	> 💡 Just like with any aggregation, if we don't exclude the `_id` with the project stage, it will be displayed by default.


		Now that we've seen all the date operators and know how to use them, let's take a look at an example of all operators being used in the same aggregation.

		Note: We are using the same document[1] as in the previous insights.

	Note: We are using the same document[1] as in the previous insights.
	> 💡 We are using the same document[1] as in the previous insights.

Add Date aggregation #1585

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Stefan-Stojanovic commented Oct 25, 2019

enki-hq commented Oct 25, 2019 • edited

Insight previews:

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enki-hq commented Oct 25, 2019 •

edited