camper/pkg/database/db.go

117 lines
2.6 KiB
Go
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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/
2023-07-22 22:11:00 +00:00
/*
* SPDX-FileCopyrightText: 2023 jordi fita mas <jfita@peritasoft.com>
* SPDX-License-Identifier: AGPL-3.0-only
*/
package database
import (
"context"
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
"errors"
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
"log"
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
2023-07-26 11:49:47 +00:00
"github.com/jackc/pgconn"
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
"github.com/jackc/pgx/v4"
"github.com/jackc/pgx/v4/pgxpool"
)
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 ErrorIsNotFound(err error) bool {
return errors.Is(err, pgx.ErrNoRows)
}
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
func New(ctx context.Context, connString string) (*DB, error) {
config, err := pgxpool.ParseConfig(connString)
if err != nil {
return nil, err
}
config.AfterConnect = func(ctx context.Context, conn *pgx.Conn) error {
if _, err := conn.Exec(ctx, "set search_path to camper, public"); err != nil {
return err
}
Implement Redsys request signature in PostgreSQL Every company need to have its own merchant code and encryption key, thus it is not possible to use environment variables to keep that data, and i have to store it in the database. I do not want to give SELECT permission on the encryption key to guest, because i am going to fuck it up sooner or later, and everyone would be able to read that secret; i know it would. Therefore, i need a security definer function that takes the data to encrypt, use the key to encrypt it, and returns the result; nobody else should have access to that key, not even admins! By the way, i found out that every merchant receives the same key, thus it is not a problem to keep it in the repository. Since i need that SQL function to encrypt the data, i thought that i may go the whole nine yards and sign the request in PostgreSQL too, after all the data to sign comes from there, and it has JSON functions to create and base64-code an object. Fortunately, pg_crypto has all the functions that i need, but i can no longer keep that extension inside the auth schema, because it is used from others, and the public schema, like every other extensions, seems more appropriate. Instead of having the list of currency and language codes that Redsys uses as constants in the code, i moved that as field to the currency and language relations, so i can simply pass the lang_tag to the function and it can transform that tag to the correct code; the currency is from the company’s relation, since it is the only currency used in the whole application (for now). As a consequence, i had to grant execute to currency and the parse_price functions to guest, too. To generate the test data used in the unit tests, i used a third-party PHP implementation[0], but i only got from that the resulting base64-coded JSON object and signature, using the same that as in the unit test, and did not use any code from there. PostgreSQL formats the JSON as text differently than most implementations i have seen: it adds spaces between the key name and the colons, and space between the value and the separating comma. The first implementation used replace() to format the JSON as exactly as the PHP implementation, so that the result matches, and then tried to do generate the form by hand using the output from PostgreSQL without the replace(), to verify that Redsys would still accept my input. Finally, i adjusted the unit test to whatever pg_prove said it was getting from the function. I still have the form’s action hard-codded to the test environment, but the idea is that administrators should be able to switch from test to live themselves. That means that i need that info in the redsys relation as well. I think this is one of the few use cases for SQL’s types, because it is unlikely to change anytime soon, and i do not need the actual labels. Unfortunately, i could not use enumerations for the request’s transaction type because i can not attach an arbitrary number to the enum’s values. Having a relation is overkill, because i would need a constant in Go to refer to its primary key anyway, thus i kept the same constant i had before for that. Language and currency constant went out, as this is in the corresponding relations. In setup_redsys i must have a separate update if the encrypt_key is null because PostgreSQL checks constraints before key conflict, and i do not want to give a default value to the key if the row is not there yet. The problem is that i want to use null to mean “keep the same password”, because it is what i intend to do with the user-facing form: leave the input empty to keep the same password. As now Go needs to pass composite types back and forth with PostgreSQL, i need to register these types, and i have to do it every time because the only moment i have access to the non-pooled connection is in the AfterConnect function, but at that point i have no idea whether the user is going to request a payment. I do not know how much the performance degrades because of this. [0]: https://github.com/ssheduardo/sermepa/blob/master/src/Sermepa/Tpv/Tpv.php
2023-10-26 23:52:04 +00:00
return registerTypes(ctx, conn)
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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}
config.AfterRelease = func(conn *pgx.Conn) bool {
if _, err := conn.Exec(context.Background(), "reset role"); err != nil {
log.Printf("ERROR - failed to reset role: %v", err)
return false
}
return true
}
pool, err := pgxpool.ConnectConfig(ctx, config)
if err != nil {
return nil, err
}
return &DB{pool}, nil
}
type DB struct {
*pgxpool.Pool
}
func (db *DB) Acquire(ctx context.Context) (*Conn, error) {
conn, err := db.Pool.Acquire(ctx)
if err != nil {
return nil, err
}
return &Conn{conn}, nil
}
type Conn struct {
*pgxpool.Conn
}
Add cover media to campsite types This is the image that is shown at the home page, and maybe other pages in the future. We can not use a static file because this image can be changed by the customer, not us; just like name and description. I decided to keep the actual media content in the database, but to copy this file out to the file system the first time it is accessed. This is because we are going to replicate the database to a public instance that must show exactly the same image, but the customer will update the image from the private instance, behind a firewall. We could also synchronize the folder where they upload the images, the same way we will replicate, but i thought that i would make the whole thing a little more brittle: this way if it can replicate the update of the media, it is impossible to not have its contents; dumping it to a file is to improve subsequent requests to the same media. I use the hex representation of the media’s hash as the URL to the resource, because PostgreSQL’s base64 is not URL save (i.e., it uses RFC2045’s charset that includes the forward slash[0]), and i did not feel necessary write a new function just to slightly reduce the URLs’ length. Before checking if the file exists, i make sure that the given hash is an hex string, like i do for UUID, otherwise any other check is going to fail for sure. I moved out hex.Valid function from UUID to check for valid hex values, but the actual hash check is inside app/media because i doubt it will be used outside that module. [0]: https://datatracker.ietf.org/doc/html/rfc2045#section-6.8
2023-09-10 01:04:18 +00:00
func (c *Conn) MustBegin(ctx context.Context) *Tx {
tx, err := c.Begin(ctx)
if err != nil {
panic(err)
}
return &Tx{tx}
}
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
2023-07-26 11:49:47 +00:00
func (c *Conn) MustExec(ctx context.Context, sql string, args ...interface{}) pgconn.CommandTag {
tag, err := c.Conn.Exec(ctx, sql, args...)
if err != nil {
panic(err)
}
return tag
}
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 (c *Conn) GetText(ctx context.Context, sql string, args ...interface{}) (string, error) {
var result string
if err := c.QueryRow(ctx, sql, args...).Scan(&result); err != nil {
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
return "", err
}
return result, nil
}
func (c *Conn) MustGetText(ctx context.Context, sql string, args ...interface{}) string {
if result, err := c.GetText(ctx, sql, args...); err == nil {
return result
} else {
panic(err)
}
}
func (c *Conn) GetBool(ctx context.Context, sql string, args ...interface{}) (bool, error) {
var result bool
if err := c.QueryRow(ctx, sql, args...).Scan(&result); err != nil {
return false, err
}
return result, nil
}
Add cover media to campsite types This is the image that is shown at the home page, and maybe other pages in the future. We can not use a static file because this image can be changed by the customer, not us; just like name and description. I decided to keep the actual media content in the database, but to copy this file out to the file system the first time it is accessed. This is because we are going to replicate the database to a public instance that must show exactly the same image, but the customer will update the image from the private instance, behind a firewall. We could also synchronize the folder where they upload the images, the same way we will replicate, but i thought that i would make the whole thing a little more brittle: this way if it can replicate the update of the media, it is impossible to not have its contents; dumping it to a file is to improve subsequent requests to the same media. I use the hex representation of the media’s hash as the URL to the resource, because PostgreSQL’s base64 is not URL save (i.e., it uses RFC2045’s charset that includes the forward slash[0]), and i did not feel necessary write a new function just to slightly reduce the URLs’ length. Before checking if the file exists, i make sure that the given hash is an hex string, like i do for UUID, otherwise any other check is going to fail for sure. I moved out hex.Valid function from UUID to check for valid hex values, but the actual hash check is inside app/media because i doubt it will be used outside that module. [0]: https://datatracker.ietf.org/doc/html/rfc2045#section-6.8
2023-09-10 01:04:18 +00:00
func (c *Conn) GetInt(ctx context.Context, sql string, args ...interface{}) (int, error) {
var result int
err := c.QueryRow(ctx, sql, args...).Scan(&result)
return result, err
}
Add cover media to campsite types This is the image that is shown at the home page, and maybe other pages in the future. We can not use a static file because this image can be changed by the customer, not us; just like name and description. I decided to keep the actual media content in the database, but to copy this file out to the file system the first time it is accessed. This is because we are going to replicate the database to a public instance that must show exactly the same image, but the customer will update the image from the private instance, behind a firewall. We could also synchronize the folder where they upload the images, the same way we will replicate, but i thought that i would make the whole thing a little more brittle: this way if it can replicate the update of the media, it is impossible to not have its contents; dumping it to a file is to improve subsequent requests to the same media. I use the hex representation of the media’s hash as the URL to the resource, because PostgreSQL’s base64 is not URL save (i.e., it uses RFC2045’s charset that includes the forward slash[0]), and i did not feel necessary write a new function just to slightly reduce the URLs’ length. Before checking if the file exists, i make sure that the given hash is an hex string, like i do for UUID, otherwise any other check is going to fail for sure. I moved out hex.Valid function from UUID to check for valid hex values, but the actual hash check is inside app/media because i doubt it will be used outside that module. [0]: https://datatracker.ietf.org/doc/html/rfc2045#section-6.8
2023-09-10 01:04:18 +00:00
func (c *Conn) GetBytes(ctx context.Context, sql string, args ...interface{}) ([]byte, error) {
var result []byte
err := c.QueryRow(ctx, sql, args...).Scan(&result)
return result, err
}