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Now there's one more command I want to show you, for that let's cycle through the past commands to the

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command where I pushed a single hobby to Maria

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and let me change this to hiking.

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Now here I push a single object, the command I'll show you will not work with each with that array

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but if you push one object which I can do with push of course, you can also use addToSet instead.

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If I hit enter, you see one document was modified

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and if I find them all, you see hiking is there.

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The question is what is the difference to push? That should become clearer once I try the exact same

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command again. Previously with push,

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we were able to push duplicate values.

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Now you see modified count is 0,

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we get no error but you see nothing was changed

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and indeed if we look into the data, there is still only one hiking hobby.

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The difference is that addToSet adds unique values only,

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so if you try to add a value that's already part of the array, it will not be added again

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and that can of course also be helpful in some situations.