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We get our flights in the database again

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and now let me dive a bit deeper into how we can find data. Thus far,

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we always used this way of finding data, find with no arguments.

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Now just as you can filter for specific records or documents when deleting or updating, you can also

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do so when finding.

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So I can access my flight data here,

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let me quickly clear this to make it a bit easier to read

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and instead of passing nothing, you can pass a document to it which will be interpreted as a filter for

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your collection and you can filter for anything that makes sense.

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You could filter for a name equal to Max but of course this returns nothing because in our collection,

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we get these two flights and there is no name field in there

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but what we can do of course is we can use flight data and find all flights that are let's say intercontinental,

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so we use that key here.

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We do so by adding a document, then the name and this can be wrapped by quotation marks but it doesn't

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have to

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and then let's say I want to find all flights where this is true, this would be a valid filter. If I now

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pretty print this which always is optional,

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just to make it easier to read, if I hit enter,

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now I get one flight and this is one flight which is an intercontinental flight.

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Of course, this is a very useful feature because in pretty much every application you're creating,

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you are not always interested in all your data but in a subset of the data which you need for that specific

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webpage you're showing to the user or that specific part of your mobile app. You're also not limited

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to simple queries like this,

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we could also find all flights with a distance greater than ten thousand kilometers and for this, we

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just need to modify the syntax a bit more.

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It's easy to look for equal values, distance 12000 like this,

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that would be simple and it gives us back this one flight here, just not pretty printed

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but if we want to have a greater than check, we can do that too.

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And there we just need to pass another document or object,

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I'll use these words interchangeably,

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we need to pass another object as a value for distance

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and here we again use one of these special operators provided by mongodb, $gt which

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stands for greater than and no worries,

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you don't need to learn them by heart right now. Gt does exist, $gt and that means greater than

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and then you enter the value which you want to have as a greater than value.

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So here we could enter 10000

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and let's also pretty print this to make

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it a bit easier to read and we get this one flight which has a distance greater than 10000.

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The other flight had a distance of 950 and therefore if I modify this to look for all flights with

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a distance greater than 900, we actually get back both flights,

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so this is of course another very useful feature.

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Now let me close this lecture or end this lecture by showing you findOne with this example.

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So I'm looking for flights with a distance greater than 900 kilometers, if I switch it from find to findOne

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and I remove pretty here because pretty is not supported on findOne, I get back only one flight, the

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first flight that matched my criteria and that makes sense because findOne only gives me back one

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element.

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So if I want to find all, I should use find, if I am only interested in the first matching element, findOne is the

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solution.

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Important is it will still respect that filter but then not look for all matching elements but only

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the first matching element.