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In this lesson we're going to talk about using location blocks in the engine configuration.

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This is the most used context in any engineered configuration and it's how will define and configure

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the behaviour of specific you are our eyes or requests.

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Think of location blocks as intercepting a request based on its value and then doing something other

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than just trying to serve a matching file relative to the root directory as we saw in the previous lesson.

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This standard behaviour is great for static resources such as our style sheet to this image etc..

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But if we request for example slash greet or any other you are my engine x cannot match a file and instead

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serves this default foro for page.

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So let's see how to use a custom location context and intercept that greet request and give it some

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hypothetical purpose back to the engine X configuration file.

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I'll add a location context inside the server context.

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But this time the context takes a parameter before opening the context braces.

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This parameter being the you are right to match.

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So in our case slash greet meaning we can now respond worth redirect or do whatever else we need to

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do with this request and essentially manipulate the response.

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Let's just return a text string for now say return which takes two arguments.

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The response code and the response data to return to the client 200.

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So okay with a response body of hello from Engine X greet location.

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Save and reload the configuration.

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Refresh.

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Greet.

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And as expected.

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We get that string return to us now.

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There are several ways of matching you our eyes on location blocks and the one we just used is called

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the prefix match.

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Meaning that it matches a request.

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You are I starting with Slash greet.

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So in other words slash greeting is also matched or even another path.

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Literally anything starting with Slash greet.

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Should we however not want this behaviour.

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We can also do an exact match.

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By adding the equal sign or modifier before the pattern.

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Change that response to show us the update.

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Reload the configuration.

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Refresh.

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And now we get a 4 0 4 as only slash greet is matched.

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And this one no longer exists but if we simply navigate to slash greet we get that new message from

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the exact match location.

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Okay so prefix and exact matches are great but we can go one step further and matsue our eyes with a

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regular expression.

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This being the reason for installing the PCR library when we installed engine X this time we'll use

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a told the character as the match modifier to indicate that this is a regular expression match.

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I'll again do a match for Slash greet and let's say any number from 0 to 9.

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After that used this same return statement with a new message safe reload the configuration.

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Still at slash greet We now get a foro for as of course that matches.

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Also looking for a number from 0 to 9 after slash greet add a number to the you are I however.

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And again it works very importantly.

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Note that this told a modifier is case sensitive.

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So if we change one of these characters to an upper case like so.

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We're back to a foro for.

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To match case insensitive then so disregard that you are right case all together we can simply add an

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asterisk after that older like so.

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With a new message.

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Save reload dry slash greet with the uppercase character Ghen and now it works.

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Engine exercise is a priority to each of these.

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Location match modifiers with a regular expression being more important than a prefix match.

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We can test this by uncomment ing the original prefix.

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Make their capital G too.

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Exactly as we have it in the browser whilst also leaving the case insensitive regular expression match

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safe.

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Reload and the regular expression matched all ones regardless even if the order in which these location

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blocks are configured the final modifier is what's called preferential prefix which we write as carit

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told her.

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This is essentially the same as the basic prefix modifier only more important than a regular expression

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match save and reload.

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The prefix wins over the regular expression.

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It's important to understand the order of priority in which engine X matches requests.

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So to sum up they are as follows.

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Number one is the exact match.

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Should an exact match exist for a you are right that will always be the location block used regardless

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of any other matching location block.

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Second is the preferential prefix.

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Again this is the same as the basic prefix match but have priority over regular expression matches.

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Third in equal order is the regular expression.

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Matches should however both a case sensitive and case in sensitive location match your request.

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Not that this should ever really happen.

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The first block will be used as engineers has no other way of prioritizing one over the other.

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And finally the lowest of the lot is the very basic prefix matched that we looked at first.

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Any other match from the variations above will be prioritized over this one.

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That covers the basics of creating location context and matching you are rice in the next list and will

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cover the basics of Engineers variables.