Eve: Building RESTful APIs with MongoDB and Flask Transcripts
Chapter: Schema definitions and validation
Lecture: Built-in validation rules
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All right, as you can see, while you weren't watching, I went back to our basic app and expanded the schema definition a little bit.
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I added new rules for the fields we already know, and also added new fields like born, age, role etc. First name is still a string,
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but now it has min and max length rules, which, of course, means that when a value comes in with this field, it must be between 1 and 30 in length.
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Last name is more interesting, again, it's still a string, but now we also have a max length and the field is also required and must be unique.
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Now by default, fields are not required. So first name here you don't have to provide it with every single document.
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If you don't have a first name with your document, it's fine, the document will be saved anyway,
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but last name you have to provide it because it is required. And not only that, it is also unique, which means that the value coming with the document
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must be the only one in the endpoint for this field. So if we already have a John Doe and we try to save a Mike Doe,
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we get an error because the value for last name is not unique. So pretty powerful, it works really well with Mongo.
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There is one small caveat you want to know about and that is that if you have bulk inserts enabled at your endpoint,
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because the unique rule is only checked against the document already stored on the data set.
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If you have five documents coming into your system with the same request and they have duplicated value for the last name,
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as long as this last name does not exist in the database, they will be accepted. If this is a risk you don't want to run
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you might disable bulk inserts for the endpoint, so the clients are forced only save one document at a time,
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or you might want to build a custom validator which will also check the values within the document.
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Next, we have the born field which is new, and it is of type datetime. Speaking of types, we only saw the string and now the datetime type
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If we go to the documentation site, we see that we have a number of options there Of course, the basic ones like boolean, integer, float, number
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which is basically integer and float values allowed, datetime, dictionaries, lists, media, which is very interesting,
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it allows us to store images, pictures and movies, and if we're using the Mongo data layer which is the default,
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the one we're using in this course, we also have the Mongo types like object id, db reference, and all the GeoJson types
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like point, multi point, etc, and also the decimal tag type which only recently has been added to the Mongo features set.
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Age is read only, which means that clients can't write or overwrite it. So documents coming into the API cannot have the age field
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otherwise they will be rejected. So why would you want to add this field to the schema?
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Well, the reason is that by default, Eve will only return fields it knows about. So you still want to add age if you want
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this field to be returned from the database to your clients. Next up is role, role is a list, and it comes with two new rules,
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one is allowed, which supports a list of allowed values for the field and the second one is very interesting, and it is default
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which means that whenever a document comes in with no value for this field, a default will be set by the framework and stored with the document.
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So in this case, every time a document with no role comes in, a default role of author will be set for this field.
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The last field I added to the schema definition for the people endpoint is location. As you can see, this is of type dict
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and because it is a dictionary, we can define a schema for the dictionary itself. In Mongo DB terms, this is going to be a subdocument
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and when we define a sub document, we can also define its schema, so again, all the validation rules we've been setting for the main document
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can also be set for the subdocument. Here we only have two fields for the location which are address and city.
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City is a string as address, but it is also required. Now, because location itself is not required.
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We aren't requested to provide this feed with every document, but if we provide field, then the city field is required and should be added,
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otherwise, the document will be rejected. If we wanted a location to be required, we need to do this, so in this case location is required,
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and when we provide it, we also have to provide city while we can avoid providing address.
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All right, I already saved these new settings and also relaunched let me know about the postman and try to make a post of a new document
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like the ones we have been storing so far. So only a first name field set to Bill. If we send this request over, what we get back is
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as expected, an unprocessable entity error, with two issues, one for the location field
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which is missing and it is required, and the same for last name, both of them are indeed required as per our settings.
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So, let's go back to our request and add values, let's pretend I forget to add the city
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okay, let's try to send these over, new errors, as you can see, last name now, we provided the last name value
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but it is not unique because on the people endpoint we already have a John Doe so since last name is unique, this value is not accepted,
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and then the location, we provided that location field but the city field within the location subdocument is still missing, so let's fix this.
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All right, now we should be good to go, let's try that, great, so this time we get a created status code,
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we can go and do a get request to our document endpoint we get the unique id of the document and hit the endpoint there,
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and yes, we have the unique id of course, first name, last name, location
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as we provided it, but we also have a role field with the default value of author. Of course, the age field is still missing
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it was read only so we didn't provide it, but there is no age field in the document on the data set,
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so it is not being returned by the API, but that's fine.