1 00:00:03,950 --> 00:00:09,370 In this exercise, we will continue with the previous exercise where we 2 00:00:09,370 --> 00:00:14,650 developed the interaction between the node application and the MongoDB server. 3 00:00:14,650 --> 00:00:18,120 In this exercise, I am going to encapsulate a few of 4 00:00:18,120 --> 00:00:21,750 the database operations into a node module of its own, 5 00:00:21,750 --> 00:00:23,540 a file-based node module, 6 00:00:23,540 --> 00:00:29,345 and then make use of it within my node application in order to interact with the server. 7 00:00:29,345 --> 00:00:31,940 At the same time, we'll perform several operations on 8 00:00:31,940 --> 00:00:35,630 the server to demonstrate that we will be able 9 00:00:35,630 --> 00:00:43,040 to interact with the server using our node application and the node MongoDB driver. 10 00:00:43,040 --> 00:00:47,605 To get started, let's go to our project, 11 00:00:47,605 --> 00:00:53,975 and then create a new file named operations.js. 12 00:00:53,975 --> 00:00:57,720 This file will encapsulate all that database operations, 13 00:00:57,720 --> 00:01:00,705 the four operations that I'm going to perform insert, 14 00:01:00,705 --> 00:01:05,855 find, remove and update a document in my database. 15 00:01:05,855 --> 00:01:09,980 Now, this will be organized as a file-based node module, 16 00:01:09,980 --> 00:01:15,070 which then I will make use of it in my node application to access the server. 17 00:01:15,070 --> 00:01:16,330 So, to get started, let 18 00:01:16,330 --> 00:01:25,780 me first require assert, 19 00:01:25,780 --> 00:01:27,565 in this node module, 20 00:01:27,565 --> 00:01:30,225 and since this happens to be a node module, 21 00:01:30,225 --> 00:01:35,055 we'll be exporting several methods from the node module. 22 00:01:35,055 --> 00:01:41,705 The first method would be insert document obviously as you would expect, 23 00:01:41,705 --> 00:01:44,520 and this will take four parameters DB, 24 00:01:44,520 --> 00:01:49,555 the MongoDB, database connection within my node application, 25 00:01:49,555 --> 00:01:54,240 that I will obtain within the node application. 26 00:01:54,240 --> 00:01:57,785 Then the second one is the document which I want to insert. 27 00:01:57,785 --> 00:02:02,800 The third parameter is the collection into which I want to insert the document. 28 00:02:02,800 --> 00:02:05,675 The last one is a callback function, 29 00:02:05,675 --> 00:02:10,425 which will be called back once that operation is completed. 30 00:02:10,425 --> 00:02:14,800 Then let's close the function here, 31 00:02:14,800 --> 00:02:20,100 and this essentially encapsulates the insert document method here. 32 00:02:20,100 --> 00:02:27,415 So, this is a function which is exported by this node module here. 33 00:02:27,415 --> 00:02:34,250 Now, I'm going to also incorporate a few more methods here. 34 00:02:34,250 --> 00:02:42,870 The second one would be finddocuments. 35 00:02:42,870 --> 00:02:46,025 Not just one but several documents. 36 00:02:46,025 --> 00:02:54,390 This I would search the collection and find all the documents that are in the collection. 37 00:02:54,390 --> 00:02:58,130 So, that's why I'm only taking the database 38 00:02:58,130 --> 00:03:02,090 and the collection as the two parameters along with the callback. 39 00:03:02,090 --> 00:03:11,550 The third function that I'm going to implement an export from here is the removedocument. 40 00:03:12,290 --> 00:03:15,590 This supports the delete operation, 41 00:03:15,590 --> 00:03:19,855 and so the name of document will take the database, the document, 42 00:03:19,855 --> 00:03:23,775 the collection and the callback as the four parameters, 43 00:03:23,775 --> 00:03:30,595 and we'll call the callback when the operation is completed. 44 00:03:30,595 --> 00:03:34,445 The final one of course is to update the document. 45 00:03:34,445 --> 00:03:38,120 Now of course, you don't necessarily have to do it this way. 46 00:03:38,120 --> 00:03:42,830 I just felt that this would be another way of illustrating how you can 47 00:03:42,830 --> 00:03:49,110 encapsulate that functions into its own node module. 48 00:03:49,110 --> 00:03:55,395 This is just reorganizing the code in a way that is more easier to use. 49 00:03:55,395 --> 00:03:57,205 So, for the exports, 50 00:03:57,205 --> 00:04:00,070 for the update document it takes the DB, 51 00:04:00,070 --> 00:04:03,750 some way of identifying the document as a second parameter. 52 00:04:03,750 --> 00:04:06,205 The third parameter is the update, 53 00:04:06,205 --> 00:04:08,750 and the fourth parameter is the collection in which 54 00:04:08,750 --> 00:04:11,505 this document exists, and the callback. 55 00:04:11,505 --> 00:04:18,160 So, four functions to be exported by the operations.js file. 56 00:04:18,160 --> 00:04:20,380 Now, within this functions, 57 00:04:20,380 --> 00:04:21,735 let's implement one by one. 58 00:04:21,735 --> 00:04:23,420 In the insert document, 59 00:04:23,420 --> 00:04:27,680 the first thing that I'm going to do is say 60 00:04:27,680 --> 00:04:36,000 const collection and it'll say DB collection, 61 00:04:38,930 --> 00:04:44,710 and the parameter is the collection. 62 00:04:45,350 --> 00:04:50,190 So, we'll look for the collection there. 63 00:04:50,190 --> 00:04:54,640 Now, this has to be performed in all the four methods. 64 00:04:54,640 --> 00:04:59,990 So, I'm going to go and paste this code into all the four methods here, 65 00:05:01,140 --> 00:05:05,390 because that's a function that I need in all of them. 66 00:05:05,390 --> 00:05:07,820 So, once I get hold of the collection, 67 00:05:07,820 --> 00:05:11,680 then as you recall from the previous exercise, 68 00:05:11,680 --> 00:05:13,895 I can perform operations on the collection. 69 00:05:13,895 --> 00:05:19,160 So, I'll say collection, insert, 70 00:05:21,300 --> 00:05:27,610 and this takes as the first parameter the document to be inserted, 71 00:05:27,610 --> 00:05:35,695 and the second parameter is the callback with the error and that result. 72 00:05:35,695 --> 00:05:40,990 So, now when this document 73 00:05:40,990 --> 00:05:46,780 is inserted by calling the insert method on the database collection, 74 00:05:46,780 --> 00:05:49,180 the insert method let me remind you, 75 00:05:49,180 --> 00:05:52,090 is supported by the MongoDB driver. 76 00:05:52,090 --> 00:05:53,980 So, that's the method that we're using here, 77 00:05:53,980 --> 00:05:56,420 or that's the function that we're using here. 78 00:05:56,420 --> 00:06:05,060 Now, the first thing that I'm going to check for this, assertequal err, null. 79 00:06:05,060 --> 00:06:09,185 So, I want to make sure that I don't have an error. 80 00:06:09,185 --> 00:06:11,225 So I want to make sure that the error is null. 81 00:06:11,225 --> 00:06:12,470 If it is not null, 82 00:06:12,470 --> 00:06:15,930 then this will print out the information and then quit the application. 83 00:06:15,930 --> 00:06:19,760 At this moment, I feel that this is okay to handle it that later on, 84 00:06:19,760 --> 00:06:24,680 we'll see how we can have a global way of handling all the errors when we 85 00:06:24,680 --> 00:06:34,390 implement in the next lesson another way of accessing the MongoDB database. 86 00:06:34,390 --> 00:06:36,640 Now, after I do this, 87 00:06:36,640 --> 00:06:38,050 I'm going to implement, 88 00:06:38,050 --> 00:06:40,075 I'm going to simply log this information. 89 00:06:40,075 --> 00:06:48,570 So I'll say, console log and insert it. 90 00:06:48,570 --> 00:06:55,375 So, this information will be printed out to the screen here, inserted. 91 00:06:55,375 --> 00:07:00,440 Now again, remember the semicolons and all that are 92 00:07:00,440 --> 00:07:05,120 important don't forget them when you are typing in your code. 93 00:07:05,120 --> 00:07:07,930 So, I'll say inserted result. 94 00:07:07,930 --> 00:07:12,165 This result object that is returned, 95 00:07:12,165 --> 00:07:15,785 will have on it a property called the result property, 96 00:07:15,785 --> 00:07:20,270 and this property will contain a value. 97 00:07:20,270 --> 00:07:23,600 This result property is also a JavaScript object, 98 00:07:23,600 --> 00:07:31,395 and this will contain a property n which tells us how many documents have been inserted. 99 00:07:31,395 --> 00:07:36,875 So that's the information that I'm going to print out here, 100 00:07:36,875 --> 00:07:39,540 and then we'll go to the next line and 101 00:07:39,540 --> 00:07:50,750 say "documents into the collection." 102 00:07:53,070 --> 00:08:02,040 Now, this is just a way of informing the user that this operation took place correctly, 103 00:08:02,040 --> 00:08:10,135 and then they will pass that result back to our calling function. 104 00:08:10,135 --> 00:08:15,330 So, we'll call the callback and then the result will be the parameter to the callback. 105 00:08:15,330 --> 00:08:21,595 So, when we implement the usage of this function in our index.js file, 106 00:08:21,595 --> 00:08:23,930 we will be providing the callback there which will 107 00:08:23,930 --> 00:08:26,880 receive the result as the incoming parameter. 108 00:08:26,880 --> 00:08:30,670 So, this is for the "insertDocument." 109 00:08:30,670 --> 00:08:33,010 Now, for the "findDocument, 110 00:08:33,010 --> 00:08:36,750 " what I am going to do is to say, 111 00:08:37,010 --> 00:08:41,640 "coll.find" and I'm going to find all the documents. 112 00:08:41,640 --> 00:08:44,810 So, that's why I will give an empty JavaScript object in here, 113 00:08:44,810 --> 00:08:51,040 which will match with all the documents in the collection and then I'll say, 114 00:08:51,040 --> 00:09:01,820 "toArray" and this will take as a parameter a callback function, 115 00:09:02,220 --> 00:09:06,505 and inside this callback function, of course, 116 00:09:06,505 --> 00:09:11,710 I will assert that this is not null, 117 00:09:11,710 --> 00:09:20,590 and then we will say, "callback docs." 118 00:09:20,590 --> 00:09:27,440 We'll simply pass back the retrieved documents back to the calling function. 119 00:09:28,200 --> 00:09:37,750 Now, for the "removeDocument," I'm going to say, "collection deleteOne." 120 00:09:37,750 --> 00:09:40,270 So, I'll try to find the first document that 121 00:09:40,270 --> 00:09:45,130 matches what we have specified and then delete it. 122 00:09:45,130 --> 00:09:47,070 And then this will take, again, 123 00:09:47,070 --> 00:09:50,380 a callback function as a second parameter, 124 00:09:50,380 --> 00:09:52,685 and inside this callback function, 125 00:09:52,685 --> 00:09:58,160 the first thing that I check is to make sure that the error is not null. 126 00:09:58,160 --> 00:10:01,820 And then after that, we will say, 127 00:10:02,130 --> 00:10:20,890 "console log removed the document comma document." 128 00:10:20,890 --> 00:10:24,840 We used the comma here because this is a JavaScript object so, 129 00:10:24,840 --> 00:10:26,890 if you specify console log like this, 130 00:10:26,890 --> 00:10:30,360 the document will be printed out and then we'll pass 131 00:10:30,360 --> 00:10:36,705 that result back through the callback function. 132 00:10:36,705 --> 00:10:47,550 And then finally, for the update we'll coll.updateOne. 133 00:10:47,670 --> 00:10:52,255 This is a method the MongoDB driver supports. 134 00:10:52,255 --> 00:10:56,560 So, I'll say, "update.One document, 135 00:10:56,560 --> 00:11:01,480 " and the second parameter is where we 136 00:11:01,480 --> 00:11:06,960 will pass in the fields that need to be updated. 137 00:11:06,960 --> 00:11:08,915 And the way it is done, 138 00:11:08,915 --> 00:11:12,810 we'll say, "dollar set colon update." 139 00:11:12,810 --> 00:11:16,100 So, this will take the update information that 140 00:11:16,100 --> 00:11:19,120 I'm sending in and then pass it into the update.One. 141 00:11:19,120 --> 00:11:21,620 The first one is the document that needs to be updated. 142 00:11:21,620 --> 00:11:25,425 The second one is which fields of the document needs to be updated here. 143 00:11:25,425 --> 00:11:28,660 And the third parameter is null, 144 00:11:28,770 --> 00:11:36,305 and that last parameter is a callback function, 145 00:11:36,305 --> 00:11:45,660 which obviously will give us the result of the operation. 146 00:11:45,660 --> 00:11:51,125 So, first thing I'm going to check to make sure that the error is not null. 147 00:11:51,125 --> 00:11:59,535 Then, I'll do a "console log updated the document with." 148 00:11:59,535 --> 00:12:03,195 Now again, the console logs are purely for us to 149 00:12:03,195 --> 00:12:07,920 ensure that the code is doing what it is doing. 150 00:12:07,920 --> 00:12:09,690 It doesn't help in any way. 151 00:12:09,690 --> 00:12:11,995 This is just for our own information. 152 00:12:11,995 --> 00:12:15,070 In a production server, 153 00:12:15,070 --> 00:12:18,570 you would not be having this console logs, maybe. 154 00:12:18,570 --> 00:12:24,220 You can disable them. So, that's it. 155 00:12:24,220 --> 00:12:32,370 So four methods being supported in this particular file-based node module insert, 156 00:12:32,370 --> 00:12:35,040 find, remove and update. 157 00:12:35,040 --> 00:12:38,490 So, now that we have implemented this file-based node module, 158 00:12:38,490 --> 00:12:41,185 let's go to the index.js file, 159 00:12:41,185 --> 00:12:45,985 and then to make use of that file-based node module, 160 00:12:45,985 --> 00:12:48,010 I need to require this here. 161 00:12:48,010 --> 00:12:53,969 So, I'll say, "const dboper require." 162 00:12:53,969 --> 00:13:00,155 Since this is a file-based node module you get the full path to the node module, 163 00:13:00,155 --> 00:13:03,865 and which in this case happens to be./operations 164 00:13:03,865 --> 00:13:09,760 because it is in the same folder as my index.js file. 165 00:13:09,760 --> 00:13:12,400 Now, once we have done this, 166 00:13:12,400 --> 00:13:19,570 then right here, this function, 167 00:13:19,570 --> 00:13:24,355 this code that we were doing to access the database now insert, 168 00:13:24,355 --> 00:13:32,430 we will be using the dboper that we have just implemented to access that database. 169 00:13:32,430 --> 00:13:36,280 So, we'll say, "dboper insert document, 170 00:13:36,280 --> 00:13:40,345 " and this "insert document" takes the db as the first parameter. 171 00:13:40,345 --> 00:13:45,015 The db here, is this db that came in when we call MongoClient connect. 172 00:13:45,015 --> 00:13:48,010 So that db will be passed in, so that way, 173 00:13:48,010 --> 00:13:53,805 my operations node module knows where to access the database. 174 00:13:53,805 --> 00:13:59,325 Then the second parameter is the, 175 00:13:59,325 --> 00:14:03,950 so if you look at the "insert document" you will see 176 00:14:03,950 --> 00:14:08,055 that the second parameter is the document to be inserted. 177 00:14:08,055 --> 00:14:10,850 So, I will say, "name. " 178 00:14:11,640 --> 00:14:21,680 I'm just going to construct a JSON object or JavaScript object here, 179 00:14:21,680 --> 00:14:27,315 which will automatically be mapped into adjacent object when it is being inserted. 180 00:14:27,315 --> 00:14:30,135 And the third parameter, as you see, 181 00:14:30,135 --> 00:14:32,790 "db document collection and callback." 182 00:14:32,790 --> 00:14:36,690 So the third parameter is the collection and the collection is 183 00:14:36,690 --> 00:14:42,855 the dishes collection and the final one is the callback. 184 00:14:42,855 --> 00:14:48,605 The call back again as you recall receives the result. 185 00:14:48,605 --> 00:14:52,710 If you look back at the baby implemented the insert document, 186 00:14:52,710 --> 00:14:55,245 the callback received the result as the parameter. 187 00:14:55,245 --> 00:15:00,305 So inside this callback we will handle that result value here. 188 00:15:00,305 --> 00:15:07,000 So, when the result value comes in we'll do a console.log. 189 00:15:07,390 --> 00:15:12,750 We'll say insert document 190 00:15:13,240 --> 00:15:20,565 backslash N and we'll say result OPS. 191 00:15:20,565 --> 00:15:24,760 The OPS tells you the number of insert operations that were carried out. 192 00:15:24,760 --> 00:15:28,680 So this is another object that is going to be on the result 193 00:15:28,680 --> 00:15:31,790 JavaScript object that is passed back in as 194 00:15:31,790 --> 00:15:34,650 the parameter and so I'm just going to print out that value. 195 00:15:34,650 --> 00:15:38,260 So that'll give us some information about what has happened. 196 00:15:38,260 --> 00:15:40,610 Now once this is completed, 197 00:15:40,610 --> 00:15:45,880 inside this callback function I'm going to call the next database operation. 198 00:15:45,880 --> 00:15:50,730 So I'll say dboper and then find the documents. 199 00:15:50,730 --> 00:16:00,260 Then I'll say dbdishes and the third parameter is docs, 200 00:16:00,260 --> 00:16:03,090 which is the callback function. 201 00:16:03,090 --> 00:16:06,100 When I receive the docs I'm going to do a 202 00:16:06,100 --> 00:16:15,170 console.log saying found documents, 203 00:16:16,170 --> 00:16:22,140 and we'll simply lock the documents to the screen. 204 00:16:22,140 --> 00:16:25,075 So, this will print out the found documents. 205 00:16:25,075 --> 00:16:28,470 Notice that this call is inside 206 00:16:28,470 --> 00:16:37,480 the callback function that is applied for the earlier function call, 207 00:16:37,480 --> 00:16:41,225 so that is something that I want you to notice specifically. 208 00:16:41,225 --> 00:16:46,290 Now, again inside this function call they need to do it this way because until 209 00:16:46,290 --> 00:16:52,185 this callback is called we cannot do the next operation. 210 00:16:52,185 --> 00:16:58,855 So, in that next operation I'm going to update the document that I have just inserted. 211 00:16:58,855 --> 00:17:03,990 So I will say update the document and I'll say Update Document DB, 212 00:17:03,990 --> 00:17:07,880 and then the next parameter is the document 213 00:17:07,880 --> 00:17:11,800 and I don't need to specify the entire document I can only specify one field and 214 00:17:11,800 --> 00:17:20,740 then that'll find the document that matches this particular field. 215 00:17:21,960 --> 00:17:27,690 What I'm going to do is the next parameter is the update that needs to be supplied. 216 00:17:27,690 --> 00:17:30,770 So, the update is which field I want to update, 217 00:17:30,770 --> 00:17:35,350 so I'm going to update 218 00:17:35,350 --> 00:17:42,050 the description field by saying Updated Test, 219 00:17:43,030 --> 00:17:48,475 and then the fourth one is the collection which is Dishes, 220 00:17:48,475 --> 00:17:53,820 and the final one is the callback function which obtains 221 00:17:53,820 --> 00:18:01,110 the docs as the return value or 222 00:18:01,110 --> 00:18:08,705 rather result of the update operation that we just carried out. 223 00:18:08,705 --> 00:18:11,890 Then inside this callback function, 224 00:18:11,890 --> 00:18:20,845 I'm going to again do a console.log saying 225 00:18:20,845 --> 00:18:31,050 updated document backslash N. The updated document will be passed 226 00:18:31,050 --> 00:18:38,125 back in result.result on 227 00:18:38,125 --> 00:18:43,115 this property of the result object that is passed tracking. 228 00:18:43,115 --> 00:18:49,044 Again notice how the calls are getting nested 229 00:18:49,044 --> 00:18:54,585 inside the callback functions here. 230 00:18:54,585 --> 00:18:57,880 I want you to notice this structure of the code 231 00:18:57,880 --> 00:19:03,130 specifically because that is what I'm going to come back to in the next exercise. 232 00:19:03,130 --> 00:19:05,760 Now after I do that, 233 00:19:05,760 --> 00:19:07,529 I'm going to find the documents, 234 00:19:07,529 --> 00:19:12,930 so let me just copy that and then I'm going to use the same code here. 235 00:19:13,840 --> 00:19:19,530 So I will say, find documents. 236 00:19:20,000 --> 00:19:27,695 Inside here I am again going to say, found updated document. 237 00:19:27,695 --> 00:19:30,375 Then finally when I'm done with this, 238 00:19:30,375 --> 00:19:35,855 I will simply call db drop collection. 239 00:19:35,855 --> 00:19:38,760 So I'm going to delete this dishes collection so that I 240 00:19:38,760 --> 00:19:41,630 will clean up my database so that I don't have 241 00:19:41,630 --> 00:19:44,350 anything more because for the next exercise I want to clean up 242 00:19:44,350 --> 00:19:47,230 the database and then start with a cleaner database. 243 00:19:47,230 --> 00:19:48,835 So, I'm going to clean out 244 00:19:48,835 --> 00:19:57,770 the dishes collection and then this would result in a callback. 245 00:19:59,110 --> 00:20:07,410 So inside here I'm going to do a console.log saying, 246 00:20:07,410 --> 00:20:17,000 dropped collection, and then I'll just print out the result that came in. 247 00:20:17,820 --> 00:20:25,250 Then finally, close the database. 248 00:20:25,650 --> 00:20:28,895 Note that structure of the code, 249 00:20:28,895 --> 00:20:34,580 DB insert document and inside the callback function I'm going to call 250 00:20:34,580 --> 00:20:37,690 the next function and inside 251 00:20:37,690 --> 00:20:39,660 the callback off that I'm going to call 252 00:20:39,660 --> 00:20:42,270 the next function and inside the callback next function and so on. 253 00:20:42,270 --> 00:20:46,990 So, you see a nested set of callbacks here and 254 00:20:46,990 --> 00:20:52,665 a tree structured nested set of call backs here. 255 00:20:52,665 --> 00:20:56,505 That is something that I want you to pay attention to. 256 00:20:56,505 --> 00:21:02,680 Let's save the changes and go and look at this version of our application. 257 00:21:02,680 --> 00:21:04,725 Getting back to the terminal, 258 00:21:04,725 --> 00:21:08,045 let me execute the application. 259 00:21:08,045 --> 00:21:13,035 So let me type NPM start and we'll see that result. 260 00:21:13,035 --> 00:21:19,060 Now, from this result you can see that the document is inserted 261 00:21:19,060 --> 00:21:25,330 into the collection and that is the document that has been found. 262 00:21:25,330 --> 00:21:26,990 In the second step, 263 00:21:26,990 --> 00:21:31,540 we are finding the document so when we call the DB find document, 264 00:21:31,540 --> 00:21:36,175 so this is the document that is retrieved from my collection. 265 00:21:36,175 --> 00:21:39,010 Then I ask it to update the document with 266 00:21:39,010 --> 00:21:42,915 this and then you'll notice that it says updated document and then 267 00:21:42,915 --> 00:21:46,850 here it prints the result or OPS and it says N is equal to 268 00:21:46,850 --> 00:21:51,775 one number modified as one and it was okay. 269 00:21:51,775 --> 00:21:57,010 Then it prints out the updated document, 270 00:21:57,010 --> 00:22:02,020 we find the updated document here and that is what is printed out here, 271 00:22:02,020 --> 00:22:05,770 and note in particular that the description has been updated. 272 00:22:05,770 --> 00:22:09,390 Then finally, it dropped the collection. 273 00:22:09,990 --> 00:22:16,690 So we see how this application runs and is able to make use of 274 00:22:16,690 --> 00:22:23,410 the node module that we implemented and then performed various database operations. 275 00:22:23,410 --> 00:22:26,560 With this we complete this exercise. 276 00:22:26,560 --> 00:22:31,520 In this exercise I have demonstrated to you how you would interact with 277 00:22:31,520 --> 00:22:37,085 your MongoDB server from your node application. 278 00:22:37,085 --> 00:22:43,455 We have implemented our own node module here and then used it 279 00:22:43,455 --> 00:22:46,810 within our node application by encapsulating 280 00:22:46,810 --> 00:22:50,965 certain of the database operations into that node module. 281 00:22:50,965 --> 00:22:54,020 This is a good time for you to do a Git commit with 282 00:22:54,020 --> 00:22:58,860 the message node MongoDB example part two.