WEBVTT 00:04.500 --> 00:10.260 In this lesson we're going to talk about using location blocks in the engine configuration. 00:10.260 --> 00:15.630 This is the most used context in any engineered configuration and it's how will define and configure 00:15.660 --> 00:19.750 the behaviour of specific you are our eyes or requests. 00:19.770 --> 00:25.530 Think of location blocks as intercepting a request based on its value and then doing something other 00:25.530 --> 00:32.410 than just trying to serve a matching file relative to the root directory as we saw in the previous lesson. 00:32.550 --> 00:38.610 This standard behaviour is great for static resources such as our style sheet to this image etc.. 00:38.880 --> 00:46.290 But if we request for example slash greet or any other you are my engine x cannot match a file and instead 00:46.290 --> 00:49.050 serves this default foro for page. 00:49.170 --> 00:55.410 So let's see how to use a custom location context and intercept that greet request and give it some 00:55.410 --> 00:59.410 hypothetical purpose back to the engine X configuration file. 00:59.410 --> 01:03.300 I'll add a location context inside the server context. 01:03.540 --> 01:08.650 But this time the context takes a parameter before opening the context braces. 01:08.790 --> 01:11.700 This parameter being the you are right to match. 01:11.700 --> 01:18.660 So in our case slash greet meaning we can now respond worth redirect or do whatever else we need to 01:18.660 --> 01:22.920 do with this request and essentially manipulate the response. 01:22.920 --> 01:29.070 Let's just return a text string for now say return which takes two arguments. 01:29.130 --> 01:34.770 The response code and the response data to return to the client 200. 01:34.770 --> 01:40.780 So okay with a response body of hello from Engine X greet location. 01:42.590 --> 01:45.560 Save and reload the configuration. 01:47.850 --> 01:48.440 Refresh. 01:48.460 --> 01:49.660 Greet. 01:49.690 --> 01:50.640 And as expected. 01:50.640 --> 01:53.790 We get that string return to us now. 01:53.820 --> 01:58.920 There are several ways of matching you our eyes on location blocks and the one we just used is called 01:58.950 --> 02:00.390 the prefix match. 02:00.480 --> 02:02.010 Meaning that it matches a request. 02:02.010 --> 02:05.250 You are I starting with Slash greet. 02:05.370 --> 02:11.450 So in other words slash greeting is also matched or even another path. 02:11.580 --> 02:14.640 Literally anything starting with Slash greet. 02:15.590 --> 02:17.630 Should we however not want this behaviour. 02:17.630 --> 02:19.880 We can also do an exact match. 02:20.610 --> 02:24.660 By adding the equal sign or modifier before the pattern. 02:25.530 --> 02:28.410 Change that response to show us the update. 02:29.990 --> 02:32.030 Reload the configuration. 02:32.760 --> 02:34.360 Refresh. 02:34.500 --> 02:38.460 And now we get a 4 0 4 as only slash greet is matched. 02:38.490 --> 02:45.240 And this one no longer exists but if we simply navigate to slash greet we get that new message from 02:45.240 --> 02:47.160 the exact match location. 02:47.560 --> 02:53.280 Okay so prefix and exact matches are great but we can go one step further and matsue our eyes with a 02:53.280 --> 02:54.880 regular expression. 02:54.900 --> 03:00.570 This being the reason for installing the PCR library when we installed engine X this time we'll use 03:00.630 --> 03:06.990 a told the character as the match modifier to indicate that this is a regular expression match. 03:07.020 --> 03:12.810 I'll again do a match for Slash greet and let's say any number from 0 to 9. 03:12.840 --> 03:20.880 After that used this same return statement with a new message safe reload the configuration. 03:23.130 --> 03:27.290 Still at slash greet We now get a foro for as of course that matches. 03:27.300 --> 03:33.550 Also looking for a number from 0 to 9 after slash greet add a number to the you are I however. 03:33.570 --> 03:36.380 And again it works very importantly. 03:36.420 --> 03:40.110 Note that this told a modifier is case sensitive. 03:40.530 --> 03:45.100 So if we change one of these characters to an upper case like so. 03:45.970 --> 03:47.600 We're back to a foro for. 03:49.990 --> 03:56.350 To match case insensitive then so disregard that you are right case all together we can simply add an 03:56.440 --> 03:59.780 asterisk after that older like so. 04:01.050 --> 04:02.420 With a new message. 04:03.690 --> 04:11.360 Save reload dry slash greet with the uppercase character Ghen and now it works. 04:11.360 --> 04:13.830 Engine exercise is a priority to each of these. 04:13.830 --> 04:20.140 Location match modifiers with a regular expression being more important than a prefix match. 04:20.160 --> 04:23.730 We can test this by uncomment ing the original prefix. 04:23.730 --> 04:26.730 Make their capital G too. 04:26.790 --> 04:32.700 Exactly as we have it in the browser whilst also leaving the case insensitive regular expression match 04:33.360 --> 04:34.350 safe. 04:36.400 --> 04:43.090 Reload and the regular expression matched all ones regardless even if the order in which these location 04:43.090 --> 04:50.780 blocks are configured the final modifier is what's called preferential prefix which we write as carit 04:51.040 --> 04:52.440 told her. 04:52.540 --> 04:58.720 This is essentially the same as the basic prefix modifier only more important than a regular expression 04:58.720 --> 05:01.470 match save and reload. 05:03.530 --> 05:06.540 The prefix wins over the regular expression. 05:06.590 --> 05:11.420 It's important to understand the order of priority in which engine X matches requests. 05:11.420 --> 05:14.230 So to sum up they are as follows. 05:14.360 --> 05:16.600 Number one is the exact match. 05:16.760 --> 05:22.310 Should an exact match exist for a you are right that will always be the location block used regardless 05:22.310 --> 05:24.620 of any other matching location block. 05:24.620 --> 05:27.340 Second is the preferential prefix. 05:27.350 --> 05:33.520 Again this is the same as the basic prefix match but have priority over regular expression matches. 05:33.530 --> 05:36.510 Third in equal order is the regular expression. 05:36.510 --> 05:43.010 Matches should however both a case sensitive and case in sensitive location match your request. 05:43.040 --> 05:45.070 Not that this should ever really happen. 05:45.170 --> 05:51.220 The first block will be used as engineers has no other way of prioritizing one over the other. 05:51.470 --> 05:57.090 And finally the lowest of the lot is the very basic prefix matched that we looked at first. 05:57.230 --> 06:01.820 Any other match from the variations above will be prioritized over this one. 06:02.320 --> 06:07.990 That covers the basics of creating location context and matching you are rice in the next list and will 06:07.990 --> 06:10.700 cover the basics of Engineers variables.