camper/pkg/template/render.go

58 lines
1.6 KiB
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Add the skeleton of the web application It does nothing more than to server a single page that does nothing interesting. This time i do not use a router. Instead, i am trying out a technique i have seen in an article[0] that i have tried in other, smaller, projects and seems to work surprisingly well: it just “cuts off” the URI path by path, passing the request from handler to handler until it finds its way to a handler that actually serves the request. That helps to loosen the coupling between the application and lower handlers, and makes dependencies explicit, because i need to pass the locale, company, etc. down instead of storing them in contexts. Let’s see if i do not regret it on a later date. I also made a lot more packages that in Numerus. In Numerus i actually only have the single pkg package, and it works, kind of, but i notice how i name my methods to avoid clashing instead of using packages for that. That is, instead of pkg.NewApp i now have app.New. Initially i thought that Locale should be inside app, but then there was a circular dependency between app and template. That is why i created a separate package, but now i am wondering if template should be inside app too, but then i would have app.MustRenderTemplate instead of template.MustRender. The CSS is the most bare-bones file i could write because i am focusing in markup right now; Oriol will fill in the file once the application is working. [0]: https://blog.merovius.de/posts/2017-06-18-how-not-to-use-an-http-router/
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/*
* SPDX-FileCopyrightText: 2023 jordi fita mas <jfita@peritasoft.com>
* SPDX-License-Identifier: AGPL-3.0-only
*/
package template
import (
Add the logout button Conceptually, to logout we have to “delete the session”, thus the best HTTP verb would be `DELETE`. However, there is no way to send a `DELETE` request with a regular HTML form, and it seems that never will be[0]. I could use a POST, optionally with a “method override” technique, but i was planing to use HTMx anyway, so this was as good an opportunity to include it as any. In this application i am not concerned with people not having JavaScript enabled, because it is for a customer that has a known environment, and we do not have much time anyway. Therefore, i opted to forgo progressive enhancement in cases like this: if `DELETE` is needed, use `hx-delete`. Unfortunately, i can not use a <form> with a hidden <input> for the CSRF token, because `DELETE` requests do not have body and the value should be added as query parameters, like a form with GET method, but HTMx does the incorrect thing here: sends the values in the request’s body. That’s why i have to use a custom header and the `hx-header` directive to include the CSRF token. Then, by default HTMx targets the triggered element for swap with the response from the server, but after a logout i want to redirect the user to the login form again. I could set the hx-target to button to replace the whole body, or tell the client to redirect to the new location. I actually do not know which one is “better”. Maybe the hx-target is best because then everything is handled by the client, but in the case of logout, since it is possible that i might want to load scripts only for logged-in users in the future, i opted for the full page reload. However, HTMx does not want to reload a page that return HTTP 401, hence i had to include the GET method to /login in order to return the login form with a response of HTTP 200, which also helps when reloading in the browser after a failed login attempt. I am not worried with the HTTP 401 when attempting to load a page as guest, because this request most probably comes from the browser, not HTMx, and it will show the login form as intended—even though it is not compliant, since it does not return the WWW-Authenticate header, but this is the best i can do given that no cookie-based authentication method has been accepted[1]. [0]: https://www.w3.org/Bugs/Public/show_bug.cgi?id=10671#c16 [1]: https://datatracker.ietf.org/doc/id/draft-broyer-http-cookie-auth-00.html
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"fmt"
Add the skeleton of the web application It does nothing more than to server a single page that does nothing interesting. This time i do not use a router. Instead, i am trying out a technique i have seen in an article[0] that i have tried in other, smaller, projects and seems to work surprisingly well: it just “cuts off” the URI path by path, passing the request from handler to handler until it finds its way to a handler that actually serves the request. That helps to loosen the coupling between the application and lower handlers, and makes dependencies explicit, because i need to pass the locale, company, etc. down instead of storing them in contexts. Let’s see if i do not regret it on a later date. I also made a lot more packages that in Numerus. In Numerus i actually only have the single pkg package, and it works, kind of, but i notice how i name my methods to avoid clashing instead of using packages for that. That is, instead of pkg.NewApp i now have app.New. Initially i thought that Locale should be inside app, but then there was a circular dependency between app and template. That is why i created a separate package, but now i am wondering if template should be inside app too, but then i would have app.MustRenderTemplate instead of template.MustRender. The CSS is the most bare-bones file i could write because i am focusing in markup right now; Oriol will fill in the file once the application is working. [0]: https://blog.merovius.de/posts/2017-06-18-how-not-to-use-an-http-router/
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"html/template"
"io"
"net/http"
"dev.tandem.ws/tandem/camper/pkg/auth"
httplib "dev.tandem.ws/tandem/camper/pkg/http"
Add the skeleton of the web application It does nothing more than to server a single page that does nothing interesting. This time i do not use a router. Instead, i am trying out a technique i have seen in an article[0] that i have tried in other, smaller, projects and seems to work surprisingly well: it just “cuts off” the URI path by path, passing the request from handler to handler until it finds its way to a handler that actually serves the request. That helps to loosen the coupling between the application and lower handlers, and makes dependencies explicit, because i need to pass the locale, company, etc. down instead of storing them in contexts. Let’s see if i do not regret it on a later date. I also made a lot more packages that in Numerus. In Numerus i actually only have the single pkg package, and it works, kind of, but i notice how i name my methods to avoid clashing instead of using packages for that. That is, instead of pkg.NewApp i now have app.New. Initially i thought that Locale should be inside app, but then there was a circular dependency between app and template. That is why i created a separate package, but now i am wondering if template should be inside app too, but then i would have app.MustRenderTemplate instead of template.MustRender. The CSS is the most bare-bones file i could write because i am focusing in markup right now; Oriol will fill in the file once the application is working. [0]: https://blog.merovius.de/posts/2017-06-18-how-not-to-use-an-http-router/
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)
func templateFile(name string) string {
return "web/templates/" + name
}
Add the company’s slug in the URL before company-dependent handlers I really doubt that they are going to use more than a single company, but the application is based on Numerus, that **does** have multiple company, and followed the same architecture and philosophy: use the URL to choose the company to manage, even if the user has a single company. The reason i use the slug instead of the ID is because i do not want to make the ID public in case the application is really used by employees of many unrelated companies: they need not need to guess how many companies there are based on the ID. I validate this slug to be a valid UUID instead of relaying on the query’s empty result because casting a string with a malformed value to UUID results in an error other than data not found. Not with that select, but it would fail with a function parameter, and i want to add that UUID check to all functions that do use slugs. I based uuid.Valid function on Parse() from Google’s uuid package[0] instead of using regular expression, as it was my first idea, because that function is an order of magnitude faster in benchmarks: goos: linux goarch: amd64 pkg: dev.tandem.ws/tandem/numerus/pkg cpu: Intel(R) Core(TM) i5-6200U CPU @ 2.30GHz BenchmarkValidUuid-4 36946050 29.37 ns/op BenchmarkValidUuid_Re-4 3633169 306.70 ns/op The regular expression used for the benchmark was: var re = regexp.MustCompile("^[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-4[a-fA-F0-9]{3}-[8|9|aA|bB][a-fA-F0-9]{3}-[a-fA-F0-9]{12}$") And the input parameter for both functions was the following valid UUID, because most of the time the passed UUID will be valid: "f47ac10b-58cc-0372-8567-0e02b2c3d479" I did not use the uuid package as is, even though it is in Debian’s repository, because i only need to check whether the value is valid, not convert it to a byte array. As far as i know, that package can not do that. Adding the Company struct into auth was not my intention, as it makes little sense name-wise, but i need to have the Company when rendering templates and the company package has templates to render, thus using the company package for the Company struct would create a dependency loop between template and company. I’ve chosen the auth package only because User is also there; User and Company are very much related in this application, but not enough to include the company inside the user, or vice versa, as the User comes from the cookie while the company from the URL. Finally, had to move methodNotAllowed to the http package, as an exported function, because it is used now from other packages, namely campsite. [0]: https://github.com/google/uuid
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func MustRender(w io.Writer, r *http.Request, user *auth.User, company *auth.Company, filename string, data interface{}) {
Add the skeleton of the web application It does nothing more than to server a single page that does nothing interesting. This time i do not use a router. Instead, i am trying out a technique i have seen in an article[0] that i have tried in other, smaller, projects and seems to work surprisingly well: it just “cuts off” the URI path by path, passing the request from handler to handler until it finds its way to a handler that actually serves the request. That helps to loosen the coupling between the application and lower handlers, and makes dependencies explicit, because i need to pass the locale, company, etc. down instead of storing them in contexts. Let’s see if i do not regret it on a later date. I also made a lot more packages that in Numerus. In Numerus i actually only have the single pkg package, and it works, kind of, but i notice how i name my methods to avoid clashing instead of using packages for that. That is, instead of pkg.NewApp i now have app.New. Initially i thought that Locale should be inside app, but then there was a circular dependency between app and template. That is why i created a separate package, but now i am wondering if template should be inside app too, but then i would have app.MustRenderTemplate instead of template.MustRender. The CSS is the most bare-bones file i could write because i am focusing in markup right now; Oriol will fill in the file once the application is working. [0]: https://blog.merovius.de/posts/2017-06-18-how-not-to-use-an-http-router/
2023-07-22 22:11:00 +00:00
layout := "layout.gohtml"
if httplib.IsHTMxRequest(r) {
layout = "htmx.gohtml"
}
Add the company’s slug in the URL before company-dependent handlers I really doubt that they are going to use more than a single company, but the application is based on Numerus, that **does** have multiple company, and followed the same architecture and philosophy: use the URL to choose the company to manage, even if the user has a single company. The reason i use the slug instead of the ID is because i do not want to make the ID public in case the application is really used by employees of many unrelated companies: they need not need to guess how many companies there are based on the ID. I validate this slug to be a valid UUID instead of relaying on the query’s empty result because casting a string with a malformed value to UUID results in an error other than data not found. Not with that select, but it would fail with a function parameter, and i want to add that UUID check to all functions that do use slugs. I based uuid.Valid function on Parse() from Google’s uuid package[0] instead of using regular expression, as it was my first idea, because that function is an order of magnitude faster in benchmarks: goos: linux goarch: amd64 pkg: dev.tandem.ws/tandem/numerus/pkg cpu: Intel(R) Core(TM) i5-6200U CPU @ 2.30GHz BenchmarkValidUuid-4 36946050 29.37 ns/op BenchmarkValidUuid_Re-4 3633169 306.70 ns/op The regular expression used for the benchmark was: var re = regexp.MustCompile("^[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-4[a-fA-F0-9]{3}-[8|9|aA|bB][a-fA-F0-9]{3}-[a-fA-F0-9]{12}$") And the input parameter for both functions was the following valid UUID, because most of the time the passed UUID will be valid: "f47ac10b-58cc-0372-8567-0e02b2c3d479" I did not use the uuid package as is, even though it is in Debian’s repository, because i only need to check whether the value is valid, not convert it to a byte array. As far as i know, that package can not do that. Adding the Company struct into auth was not my intention, as it makes little sense name-wise, but i need to have the Company when rendering templates and the company package has templates to render, thus using the company package for the Company struct would create a dependency loop between template and company. I’ve chosen the auth package only because User is also there; User and Company are very much related in this application, but not enough to include the company inside the user, or vice versa, as the User comes from the cookie while the company from the URL. Finally, had to move methodNotAllowed to the http package, as an exported function, because it is used now from other packages, namely campsite. [0]: https://github.com/google/uuid
2023-07-31 16:51:50 +00:00
mustRenderLayout(w, user, company, layout, filename, data)
Add the skeleton of the web application It does nothing more than to server a single page that does nothing interesting. This time i do not use a router. Instead, i am trying out a technique i have seen in an article[0] that i have tried in other, smaller, projects and seems to work surprisingly well: it just “cuts off” the URI path by path, passing the request from handler to handler until it finds its way to a handler that actually serves the request. That helps to loosen the coupling between the application and lower handlers, and makes dependencies explicit, because i need to pass the locale, company, etc. down instead of storing them in contexts. Let’s see if i do not regret it on a later date. I also made a lot more packages that in Numerus. In Numerus i actually only have the single pkg package, and it works, kind of, but i notice how i name my methods to avoid clashing instead of using packages for that. That is, instead of pkg.NewApp i now have app.New. Initially i thought that Locale should be inside app, but then there was a circular dependency between app and template. That is why i created a separate package, but now i am wondering if template should be inside app too, but then i would have app.MustRenderTemplate instead of template.MustRender. The CSS is the most bare-bones file i could write because i am focusing in markup right now; Oriol will fill in the file once the application is working. [0]: https://blog.merovius.de/posts/2017-06-18-how-not-to-use-an-http-router/
2023-07-22 22:11:00 +00:00
}
Add the company’s slug in the URL before company-dependent handlers I really doubt that they are going to use more than a single company, but the application is based on Numerus, that **does** have multiple company, and followed the same architecture and philosophy: use the URL to choose the company to manage, even if the user has a single company. The reason i use the slug instead of the ID is because i do not want to make the ID public in case the application is really used by employees of many unrelated companies: they need not need to guess how many companies there are based on the ID. I validate this slug to be a valid UUID instead of relaying on the query’s empty result because casting a string with a malformed value to UUID results in an error other than data not found. Not with that select, but it would fail with a function parameter, and i want to add that UUID check to all functions that do use slugs. I based uuid.Valid function on Parse() from Google’s uuid package[0] instead of using regular expression, as it was my first idea, because that function is an order of magnitude faster in benchmarks: goos: linux goarch: amd64 pkg: dev.tandem.ws/tandem/numerus/pkg cpu: Intel(R) Core(TM) i5-6200U CPU @ 2.30GHz BenchmarkValidUuid-4 36946050 29.37 ns/op BenchmarkValidUuid_Re-4 3633169 306.70 ns/op The regular expression used for the benchmark was: var re = regexp.MustCompile("^[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-4[a-fA-F0-9]{3}-[8|9|aA|bB][a-fA-F0-9]{3}-[a-fA-F0-9]{12}$") And the input parameter for both functions was the following valid UUID, because most of the time the passed UUID will be valid: "f47ac10b-58cc-0372-8567-0e02b2c3d479" I did not use the uuid package as is, even though it is in Debian’s repository, because i only need to check whether the value is valid, not convert it to a byte array. As far as i know, that package can not do that. Adding the Company struct into auth was not my intention, as it makes little sense name-wise, but i need to have the Company when rendering templates and the company package has templates to render, thus using the company package for the Company struct would create a dependency loop between template and company. I’ve chosen the auth package only because User is also there; User and Company are very much related in this application, but not enough to include the company inside the user, or vice versa, as the User comes from the cookie while the company from the URL. Finally, had to move methodNotAllowed to the http package, as an exported function, because it is used now from other packages, namely campsite. [0]: https://github.com/google/uuid
2023-07-31 16:51:50 +00:00
func mustRenderLayout(w io.Writer, user *auth.User, company *auth.Company, layout string, filename string, data interface{}) {
Add the skeleton of the web application It does nothing more than to server a single page that does nothing interesting. This time i do not use a router. Instead, i am trying out a technique i have seen in an article[0] that i have tried in other, smaller, projects and seems to work surprisingly well: it just “cuts off” the URI path by path, passing the request from handler to handler until it finds its way to a handler that actually serves the request. That helps to loosen the coupling between the application and lower handlers, and makes dependencies explicit, because i need to pass the locale, company, etc. down instead of storing them in contexts. Let’s see if i do not regret it on a later date. I also made a lot more packages that in Numerus. In Numerus i actually only have the single pkg package, and it works, kind of, but i notice how i name my methods to avoid clashing instead of using packages for that. That is, instead of pkg.NewApp i now have app.New. Initially i thought that Locale should be inside app, but then there was a circular dependency between app and template. That is why i created a separate package, but now i am wondering if template should be inside app too, but then i would have app.MustRenderTemplate instead of template.MustRender. The CSS is the most bare-bones file i could write because i am focusing in markup right now; Oriol will fill in the file once the application is working. [0]: https://blog.merovius.de/posts/2017-06-18-how-not-to-use-an-http-router/
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t := template.New(filename)
t.Funcs(template.FuncMap{
"gettext": user.Locale.Get,
"pgettext": user.Locale.GetC,
Add the skeleton of the web application It does nothing more than to server a single page that does nothing interesting. This time i do not use a router. Instead, i am trying out a technique i have seen in an article[0] that i have tried in other, smaller, projects and seems to work surprisingly well: it just “cuts off” the URI path by path, passing the request from handler to handler until it finds its way to a handler that actually serves the request. That helps to loosen the coupling between the application and lower handlers, and makes dependencies explicit, because i need to pass the locale, company, etc. down instead of storing them in contexts. Let’s see if i do not regret it on a later date. I also made a lot more packages that in Numerus. In Numerus i actually only have the single pkg package, and it works, kind of, but i notice how i name my methods to avoid clashing instead of using packages for that. That is, instead of pkg.NewApp i now have app.New. Initially i thought that Locale should be inside app, but then there was a circular dependency between app and template. That is why i created a separate package, but now i am wondering if template should be inside app too, but then i would have app.MustRenderTemplate instead of template.MustRender. The CSS is the most bare-bones file i could write because i am focusing in markup right now; Oriol will fill in the file once the application is working. [0]: https://blog.merovius.de/posts/2017-06-18-how-not-to-use-an-http-router/
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"currentLocale": func() string {
return user.Locale.Language.String()
Add the skeleton of the web application It does nothing more than to server a single page that does nothing interesting. This time i do not use a router. Instead, i am trying out a technique i have seen in an article[0] that i have tried in other, smaller, projects and seems to work surprisingly well: it just “cuts off” the URI path by path, passing the request from handler to handler until it finds its way to a handler that actually serves the request. That helps to loosen the coupling between the application and lower handlers, and makes dependencies explicit, because i need to pass the locale, company, etc. down instead of storing them in contexts. Let’s see if i do not regret it on a later date. I also made a lot more packages that in Numerus. In Numerus i actually only have the single pkg package, and it works, kind of, but i notice how i name my methods to avoid clashing instead of using packages for that. That is, instead of pkg.NewApp i now have app.New. Initially i thought that Locale should be inside app, but then there was a circular dependency between app and template. That is why i created a separate package, but now i am wondering if template should be inside app too, but then i would have app.MustRenderTemplate instead of template.MustRender. The CSS is the most bare-bones file i could write because i am focusing in markup right now; Oriol will fill in the file once the application is working. [0]: https://blog.merovius.de/posts/2017-06-18-how-not-to-use-an-http-router/
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},
Add the logout button Conceptually, to logout we have to “delete the session”, thus the best HTTP verb would be `DELETE`. However, there is no way to send a `DELETE` request with a regular HTML form, and it seems that never will be[0]. I could use a POST, optionally with a “method override” technique, but i was planing to use HTMx anyway, so this was as good an opportunity to include it as any. In this application i am not concerned with people not having JavaScript enabled, because it is for a customer that has a known environment, and we do not have much time anyway. Therefore, i opted to forgo progressive enhancement in cases like this: if `DELETE` is needed, use `hx-delete`. Unfortunately, i can not use a <form> with a hidden <input> for the CSRF token, because `DELETE` requests do not have body and the value should be added as query parameters, like a form with GET method, but HTMx does the incorrect thing here: sends the values in the request’s body. That’s why i have to use a custom header and the `hx-header` directive to include the CSRF token. Then, by default HTMx targets the triggered element for swap with the response from the server, but after a logout i want to redirect the user to the login form again. I could set the hx-target to button to replace the whole body, or tell the client to redirect to the new location. I actually do not know which one is “better”. Maybe the hx-target is best because then everything is handled by the client, but in the case of logout, since it is possible that i might want to load scripts only for logged-in users in the future, i opted for the full page reload. However, HTMx does not want to reload a page that return HTTP 401, hence i had to include the GET method to /login in order to return the login form with a response of HTTP 200, which also helps when reloading in the browser after a failed login attempt. I am not worried with the HTTP 401 when attempting to load a page as guest, because this request most probably comes from the browser, not HTMx, and it will show the login form as intended—even though it is not compliant, since it does not return the WWW-Authenticate header, but this is the best i can do given that no cookie-based authentication method has been accepted[1]. [0]: https://www.w3.org/Bugs/Public/show_bug.cgi?id=10671#c16 [1]: https://datatracker.ietf.org/doc/id/draft-broyer-http-cookie-auth-00.html
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"isLoggedIn": func() bool {
return user.LoggedIn
},
"CSRFHeader": func() string {
return fmt.Sprintf(`"%s": "%s"`, auth.CSRFTokenHeader, user.CSRFToken)
},
"CSRFInput": func() template.HTML {
return template.HTML(fmt.Sprintf(`<input type="hidden" name="%s" value="%s">`, auth.CSRFTokenField, user.CSRFToken))
},
Add the skeleton of the web application It does nothing more than to server a single page that does nothing interesting. This time i do not use a router. Instead, i am trying out a technique i have seen in an article[0] that i have tried in other, smaller, projects and seems to work surprisingly well: it just “cuts off” the URI path by path, passing the request from handler to handler until it finds its way to a handler that actually serves the request. That helps to loosen the coupling between the application and lower handlers, and makes dependencies explicit, because i need to pass the locale, company, etc. down instead of storing them in contexts. Let’s see if i do not regret it on a later date. I also made a lot more packages that in Numerus. In Numerus i actually only have the single pkg package, and it works, kind of, but i notice how i name my methods to avoid clashing instead of using packages for that. That is, instead of pkg.NewApp i now have app.New. Initially i thought that Locale should be inside app, but then there was a circular dependency between app and template. That is why i created a separate package, but now i am wondering if template should be inside app too, but then i would have app.MustRenderTemplate instead of template.MustRender. The CSS is the most bare-bones file i could write because i am focusing in markup right now; Oriol will fill in the file once the application is working. [0]: https://blog.merovius.de/posts/2017-06-18-how-not-to-use-an-http-router/
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})
if _, err := t.ParseFiles(templateFile(layout), templateFile("form.gohtml"), templateFile(filename)); err != nil {
Add the skeleton of the web application It does nothing more than to server a single page that does nothing interesting. This time i do not use a router. Instead, i am trying out a technique i have seen in an article[0] that i have tried in other, smaller, projects and seems to work surprisingly well: it just “cuts off” the URI path by path, passing the request from handler to handler until it finds its way to a handler that actually serves the request. That helps to loosen the coupling between the application and lower handlers, and makes dependencies explicit, because i need to pass the locale, company, etc. down instead of storing them in contexts. Let’s see if i do not regret it on a later date. I also made a lot more packages that in Numerus. In Numerus i actually only have the single pkg package, and it works, kind of, but i notice how i name my methods to avoid clashing instead of using packages for that. That is, instead of pkg.NewApp i now have app.New. Initially i thought that Locale should be inside app, but then there was a circular dependency between app and template. That is why i created a separate package, but now i am wondering if template should be inside app too, but then i would have app.MustRenderTemplate instead of template.MustRender. The CSS is the most bare-bones file i could write because i am focusing in markup right now; Oriol will fill in the file once the application is working. [0]: https://blog.merovius.de/posts/2017-06-18-how-not-to-use-an-http-router/
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panic(err)
}
if rw, ok := w.(http.ResponseWriter); ok {
rw.Header().Set("Content-Type", "text/html; charset=utf-8")
}
if err := t.ExecuteTemplate(w, layout, data); err != nil {
panic(err)
}
}