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Now in the last lesson we looked at how you might read and query your Mongo database for particular
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documents in particular collections.
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In this lesson I want to cover how you would update data in your database.
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We're now further along in this CRUD documentation and we're now on the update operations.
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You might remember previously from our SQL explorations we created the products table with a stock
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value as well.
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So the pen we have 32 of those and the pencil we had 12 of those.
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So now we can learn about how to update our data inside the database by adding a stock value to each
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of our documents.
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At the moment, we have two products pen and pencil and they only have an id, a name and a price field.
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If I wanted to update one of the records with a stock value as well then I might say something like
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db.product.updateOne and inside my parentheses I will insert the query criteria.
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So which document do I want to update.
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Well I actually want to update the one that has an id of 1.
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So that's going to be this document right here.
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And this is my first input to this method
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updateOne and the second input is going to be, well what do you want to update it to
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right?
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And so let me open up another set of curly braces and I'm going to use something called a set,
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so $set
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and this allows me to set a new field and value into my document.
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Well I'm going to add a new field called stock and it's going to be 32.
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And now I close off my method updateOne and I hit enter.
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And you can see that my operation was acknowledged and the query matched one document and therefore
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one document was modified or rather updated as specified here.
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Now if I use that product.find again you can see that my pen now has a stock value associated with
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it as well.
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So now it's time for a challenge.
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I want you to update our second document that has an id of 2 to have a stock field which has a value
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of 12.
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So we know that at the moment we have two records and we've managed to update our first record to have
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a stock value of 32 but we now want this second record to also have a stock value and that's going to
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be equal to 12.
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So pause the video now and try to complete the challenge.
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All right.
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So we're going to use the same method that we saw in the documentation which is db.products.
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updateOne.
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And then we're going to specify the search or filter criteria for the record or the document that we
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want to update.
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And in this case it's going to be the one that has an id of 2.
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And then the second parameter we put in here is going to be what we want to update about that record.
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So we're going to use the set operator to set a new value for a new field and the field is going to
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be called stock and the value is going to be 12 and then we close off our parentheses.
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And now we have the updateOne method passing in two parameter
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one is which record to update and the second is what to update about it.
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So now if I hit enter, you can see that we've matched 1 record using our filter and we've modified one.
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So that means if I now try and find all the products in my products collection, I now have pencil which
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has a stock of 12 and pen with a stock of 32.