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There we can do something similar.

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We can create separate functions

3
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for connecting and inserting

4
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and since we would be reusing the same logic,

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we might wanna go for some helper functions instead.

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We got that helpers folder anyways

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with some API utilities

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and there we can add a db-util.js file

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to set up our database utility functions.

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And I'll then go to the newsletter.js file

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and grab the connectDatabase and insertDocument functions,

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cut them from newsletter.js

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and instead add them in db-util

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and just change the insertDocument function

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such that it also takes the collection as a parameter

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so that we don't always talk

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to the newsletter collection here

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but to any collection we get as a parameter.

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Now we wanna export both functions

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so that we can import them into our files

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and then we can use them here in newsletter.js.

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There we can now import from our db-util file

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by going up to the helpers/db-util

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and here I'll import connectDatabase and insertDocument

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and for insertDocument, we now just also need

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to pass in that collection name

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as a second argument so that the email is inserted

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into the correct collection.

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And with that, we can go to the eventId file here

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and also import these two functions here.

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So from the helpers folder.

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We wanna import from the db-util file

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and here we also wanna import connectDatabase

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and insertDocument and then use that.

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Here, for example, we connect to the database,

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so here we wanna await connectDatabase like this

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00:02:04,000 --> 00:02:07,000
to get access to the client.

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Now, this could be failing,

39
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so just as before,

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I will wrap it in a try catch block.

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Catch any error we might be getting like that

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and create client as a variable,

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which we then set in here.

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And then in here, we wanna send back a response

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with a status code of 500

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and some message in the JSON body

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that could be connecting to the database failed.

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Like this, and then still return

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to avoid that the rest of this function executes.

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If we do connect successfully down here,

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we're inserting the comment,

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we don't wanna run this code here.

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Instead we wanna execute insertDocument,

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pass the client to insertDocument,

55
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use the comments collection

56
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and pass the newComment as a document

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that should be inserted.

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And await to get access to the result.

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And for that, we wanna make sure that in db-util,

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we actually do return that result

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so that here we also grab that result

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and return it like that.

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With that, we can insert the document

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and still use the result to then update the ID.

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Here we, by the way, also might wanna use _id

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to be in line with the automatically generated field

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because there the field name is also _id

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as you saw in the last lectures.

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Now, the main goal was to add error handling though

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and hence, I'll wrap this into a try catch block as well.

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Catch any potential errors,

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return to not execute any other code if that did fail

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and then send back a status code of 500

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and some response data

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where we again could add a message

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of Inserting comment failed.

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And now I just want to create result as a variable,

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which I actually set here to get scoping right.

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Now the only remaining part is where we get our data.

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We can also create a helper function for that

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even though we only use it here

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but still to have a uniform approach

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when it comes to working with the database.

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I will go to the db-util file

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and export another async function.

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getAllDocuments sounds like a fitting name.

87
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And here I also need the client

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and the collection from which I wanna get all documents.

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And then we can take this code

90
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where we get access to the database

91
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and then fetch all entries and comments

92
00:04:58,000 --> 00:05:02,000
and paste that into getAllDocuments.

93
00:05:03,000 --> 00:05:07,000
Now actually we might wanna accept sort,

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this sort object as a argument as well

95
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to make this function more flexible

96
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and let the caller of the function specify how documents

97
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should be sorted.

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Then we wanna use collection here

99
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and use the sort parameter here

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and ultimately, of course, return our documents.

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Like this.

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00:05:31,000 --> 00:05:34,000
Now in the eventId file,

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00:05:34,000 --> 00:05:38,000
we can import this newly added getAllDocuments function

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00:05:38,000 --> 00:05:43,000
from the db-util file and use it down there.

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00:05:43,000 --> 00:05:48,000
Here in the GET case, I wanna call getAllDocuments,

106
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pass in my client, pass in my collection name,

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which is comments

108
00:05:54,000 --> 00:05:56,000
and pass in my sort object,

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which defines that I wanna sort by id in descending order.

110
00:06:02,000 --> 00:06:04,000
Then we can remove this

111
00:06:04,000 --> 00:06:06,000
and await getAllDocuments

112
00:06:06,000 --> 00:06:10,000
to get all our documents here like this

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and return our response.

114
00:06:13,000 --> 00:06:15,000
But again, we wanna add error handling

115
00:06:15,000 --> 00:06:18,000
so we can try this and catch any errors

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00:06:18,000 --> 00:06:20,000
if something goes wrong here.

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In which case, we stop function execution with return

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and then return a different response

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where the status code is set to 500

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and we pass on some message.

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For example, here we could say Getting comments failed.

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Now, you will be able to refactor more.

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00:06:41,000 --> 00:06:44,000
For example, sending back that error response

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is always pretty much the same.

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You could also create a separate function for that,

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just as a side note.

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Now, with that, we get our documents here

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and I wanna send back a response here if that all works,

129
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otherwise we send back that error response.

130
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And we then close the client

131
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and actually now that I move to this success response

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00:07:08,000 --> 00:07:11,000
into the try block, we can remove this return statement

133
00:07:11,000 --> 00:07:14,000
to make sure that we do close the client

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00:07:14,000 --> 00:07:17,000
if we make it past try catch here.

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So to make sure that we do always get rid of that connection

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once we're done with our operations.

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And actually, I wanna do something similar here

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for inserting a comment.

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Move this success code into the try block

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and then don't return here

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so that we still do reach this part at the bottom eventually

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where we do close the connection.

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That's why I like this way of handling it better.

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I also wanna close the connection here

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if we have invalid input.

146
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So I'll copy client.close

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and add it in here

148
00:07:54,000 --> 00:07:56,000
because here I then wanna return.

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00:07:56,000 --> 00:07:58,000
I don't wanna continue with code execution.

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Hence here, I wanna close the client,

151
00:08:00,000 --> 00:08:02,000
so close the connection.

152
00:08:02,000 --> 00:08:05,000
And here we don't wanna close the connection

153
00:08:05,000 --> 00:08:08,000
because here establishing the connection failed already.

154
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So here we definitely wanna return.

155
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And with all of that,

156
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we can again test this.

157
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Again by breaking our credentials.

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Then go to a single event.

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And show the comments.

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And fetching them fails now.

161
00:08:26,000 --> 00:08:30,000
And this breaks the front end application actually

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because now we're trying to map through all comments,

163
00:08:33,000 --> 00:08:35,000
even though we got no comments.

164
00:08:35,000 --> 00:08:38,000
So we might wanna add better error handling

165
00:08:38,000 --> 00:08:39,000
on the front end as well.

166
00:08:39,000 --> 00:08:41,000
For the moment, I'll just fix it

167
00:08:41,000 --> 00:08:44,000
by bringing back my credentials and reloading.

168
00:08:45,000 --> 00:08:49,000
Now this still fails.

169
00:08:49,000 --> 00:08:52,000
So it seems like something is wrong.

170
00:08:53,000 --> 00:08:55,000
Now let's see what's wrong by reloading

171
00:08:55,000 --> 00:08:57,000
with the Network tab open

172
00:08:58,000 --> 00:09:00,000
and then if I click on Show Comments,

173
00:09:00,000 --> 00:09:02,000
this request still fails,

174
00:09:02,000 --> 00:09:05,000
connecting to the database failed here

175
00:09:05,000 --> 00:09:08,000
even though I've fixed my credentials again.

176
00:09:09,000 --> 00:09:10,000
Even though I did that,

177
00:09:10,000 --> 00:09:15,000
it looks like calling connectDatabase failed

178
00:09:15,000 --> 00:09:17,000
in my handler function here.

179
00:09:17,000 --> 00:09:20,000
And actually, I know what went wrong.

180
00:09:20,000 --> 00:09:23,000
I moved my function here,

181
00:09:23,000 --> 00:09:26,000
my helper functions here into the db-util file

182
00:09:26,000 --> 00:09:29,000
but there I'm referring MongoClient.

183
00:09:29,000 --> 00:09:30,000
We need to add that import.

184
00:09:30,000 --> 00:09:33,000
So we should grab that MongoClient import

185
00:09:33,000 --> 00:09:35,000
and remove it from the newsletter file.

186
00:09:35,000 --> 00:09:37,000
We don't need it there anymore.

187
00:09:37,000 --> 00:09:40,000
Same is true for the eventId file

188
00:09:40,000 --> 00:09:42,000
in the comments folder.

189
00:09:42,000 --> 00:09:43,000
We can get rid of it there

190
00:09:43,000 --> 00:09:47,000
but we should add this import in the db-util.js file

191
00:09:47,000 --> 00:09:51,000
because we are using MongoClient there.

192
00:09:51,000 --> 00:09:52,000
That's why connecting failed.

193
00:09:52,000 --> 00:09:55,000
I was referring to MongoClient

194
00:09:55,000 --> 00:09:57,000
without having it available.

195
00:09:58,000 --> 00:10:00,000
So now with that, if we now reload,

196
00:10:03,000 --> 00:10:05,000
loading the comments works

197
00:10:05,000 --> 00:10:09,000
and if I now break my credentials here and save this,

198
00:10:10,000 --> 00:10:12,000
if I now try to submit

199
00:10:15,000 --> 00:10:16,000
a new comment,

200
00:10:18,000 --> 00:10:21,000
this should fail and it does.

201
00:10:21,000 --> 00:10:22,000
So that works.

202
00:10:22,000 --> 00:10:24,000
Again, no feedback on the front end.

203
00:10:24,000 --> 00:10:26,000
We could add it, we don't have it here.

204
00:10:26,000 --> 00:10:29,000
If I bring back my correct credentials

205
00:10:29,000 --> 00:10:33,000
and I try the same data again, this now worked.

206
00:10:33,000 --> 00:10:36,000
If I now hide the comments and show them again,

207
00:10:36,000 --> 00:10:40,000
we see that both comments are loaded as well.

208
00:10:40,000 --> 00:10:42,000
So that is all working here

209
00:10:42,000 --> 00:10:46,000
and we now did also add error handling therefore.