## html – Firebase error: the database is not defined

``````

// Your web app's Firebase configuration
var firebaseConfig = {
apiKey: "xxxxxxxxxxxxxxxxxxxx",
authDomain: "xxxxxxxxxxxxxxxxxxxx",
databaseURL: "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
projectId: "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
storageBucket: "xxxxxxxxxxxxxxxxxxxxxxxxxxxx",
messagingSenderId: "xxxxxxxxxxxxxxxx",
appId: "xxxxxxxxxxxxxxxxx"
};
// Initialize Firebase
firebase.initializeApp(firebaseConfig);

var citiesRef = db.collection("cities");

citiesRef.doc("SF").set({
name: "San Francisco", state: "CA", country: "USA",
capital: false, population: 860000 });

``````

## e-commerce – Are there e-commerce systems that support user defined interaction with the product database?

### Context

I work as a publisher for a small publishing house. As the only person with computer skills, I also play the role of a de facto computer scientist, including the server administrator for our website. There was a real computer scientist, but he left a few years ago and I took over. We have an online store on our website, but the online store and the website itself were coded about 15 years ago by the former computer scientist, from scratch, to Classic ASP (bweurk ), using absolutely no type of coding standard (except, apparently, "Make this code as spaghetti as possible and as unreadable as possible" – a strategy that frequently involves named variables in Farsi that unfortunately I do not do not speak). As a result, it is difficult to maintain and make changes.

I'm now starting to look for ways to modernize the site and migrate it to a content management system. The site itself is not really a problem – there are a lot of things that I will have to redo and delete, but the static parts are just static pages and should be fairly easily implemented in any good CMS. The real problem is the online store.

### The problem

The current online store draws its data from an already extensive MSSQL database, containing several thousand products available, their various data spread over fifteen different tables. Existing customers and orders are stored in the same database (in different tables, of course).

I had never set up a website with an ecommerce solution, but from what I read about WooCommerce, Magento and similar solutions, a common thread for migrating existing sites towards them seems to be that the underlying product data needs to migrate to a new e-commerce system-oriented database.

Ideally, I would like to avoid doing this for several reasons:

• The existing database is quite large (about 3.5 GB) and there are many parts of it for which I do not even know what a given table is for – I'm not quite sure what that we must migrate and what not to do. to migrate, and I'm anticipating headaches
• Migration would require (I guess?) Juggling two different database structures at the same time
• There is already a fairly complete administration module on the site that allows us to create, edit and control products. I would much rather not have to redo all this module to install a new database, because it is really the largest and most complex part of the site.

The ideal solution, as far as I know, would be an ecommerce system designed to rely on interfaces to represent various aspects of online shops (products, customers, etc.), rather than d & # 39; use built-in classes linked to a database with a specific structure. In this way, I could write my own classes that retrieve the relevant data from the relevant tables in the existing database, just by expanding the correct interfaces and providing the methods with methods to correctly return the relevant data.

There are probably similar ways to do it: the interfaces were the cleanest I could imagine. I have therefore thought that someone could have created an ecommerce system that works in this way.

I tried to search for something like this, both on Google and on the StackExchange sites (mainly here and StackOverflow), but without success. All I receive seems to be very generic: "How to create an online store?" Pages or very specific question and answer pages about a particular problem with a content management system or an ecommerce solution – just as useless for the needs that I present myself. So, I turn to ask here.

The site is hosted on a Windows server running IIS 8, so it must be able to run on this platform.

What I'm looking for is a combination of CMS and e-commerce that:

• can be integrated with each other
• works on IIS 8
• supports some form of middleware to extract and write data to the database (possibly via interfaces, perhaps in another way) for the e-commerce part
• is preferably written in PHP because that's what I know best.
• is free / open source (preferably – money is absolutely an obstacle)

Does such an e-commerce solution exist?

Remarks:

1. I am do not search for answers suggesting hiring professionals for data migration and creating an updated site. There is simply no money for that; this premise of the question is not modifiable.

2. I wondered if I should post here, on StackOverflow or ServerFault, but overall, it seemed more like a webmaster request than a coding request or server administrator; so I opted for this site.

## indexed variable – The derivative does not evaluate when the function is defined

I have the following code

``````ExD = Sum[D[y[n, t], t], {n, 0, 1}];
ExS = Sum[y[n, t], {n, 0, 1}];
[Sigma][0]    = 1;
[Sigma]& # 39;[0] = 1;
there[0, t_] = [Sigma][0]    + t [Sigma]& # 39;[0]
ExD
ExS
``````

Note that when it is executed, ExD is still general for D[y[0,t], t], while ExS prints there[0,t] as it has been defined. I can not understand why the first derivative in relation to the second variable of y[0,t] do not evaluate even if there[0,t] is clearly defined and printed correctly. Should I use Evaluate[] right here?

## 8 – JS function not defined although the JS frame is attached

I have attached materialize to my library theme.

``````global style:
version: VERSION
css:
based:
materialize / css / materialize.min.css: {}
css / style.css: {}
js:
materialize / js / materialize.min.js: {minified: true}
js / layout.js: {}
dependencies:
- core / drupal
- kernel / jquery
``````

But in layout.js, I run .sidenav () and he says it's not defined.

``````(function (\$, Drupal) {
\$ (& # 39; sidenav & # 39;). sidenav ();
}) (jQuery, Drupal);
``````

I can not find the right way to call third-party functions in my custom scripts.

## mysqli – Variable not defined in PHP class

In PHP 5.5 I have a file connection.php with the connection to my database.

``````
``````

And with include, I call it in a class in another file consultations.php

``````prepare (SELECT mail FROM user WHERE mail =?);
\$ statement-> bind_param (& # 39; s, \$ mail);
\$ statement-> execute ();
\$ rs = \$ statement-> get_result ();

}
}
?>
``````

consultations.php he tells me that the variable \$ connection (defined in connection.php) is not initialized. Therefore, it does not execute the request.

An idea why this is happening?

## Irrationality of an integral defined according to a parameter.

Let $$theta (t)$$ to be a real measurable function on $$[0,1]$$. We consider
$$a + ib = int_0 ^ 1 e ^ {i theta (t)} dt.$$

Let us multiply now $$theta$$ by a scalar $$lambda in mathbb {R}$$ and consider
$$int_0 ^ 1 e ^ {i lambda theta (t)} dt = a_ lambda + ib_ lambda.$$

When are $$a _ { lambda}, b _ { lambda}$$ rational algebraic-transcendental? And about $$frac {a} {a _ { lambda}}, frac {b} {b _ { lambda}}$$?

## simplifying expressions – Calculation of defined sums of rational functions

I'm trying to calculate a rather complicated sum, $$S_n$$which in the end satisfies the relationship $$(S_n + T_n) m ^ 3 = ( frac {(n + 1) ^ 2 – 1} {n + 1}) m ^ 3$$. I should note that $$T_n$$ is also unknown. There are many intermediate sums in this calculation, for example:

``````summand = ((3 + i + 8 d + 4 j ^ 2 - m) (-2 + 2 j - n) (5 i + 8 i j + 2 i j ^ 2 -
5 m - 8 j m - 2 j ^ 2 m - i n - i j n + m n + j m n)) / (4 (1 + 2 j) ^ 2 (3 + 2 j) ^ 2)
``````
``````Sum[summand, {j, r, n/2-3,2}, Assumptions-> Mod[n,4]== 0 && Mod[r,2]== 1]// FullSimplify
``````

The output is a set of PolyGamma functions:

``````- (1/512) (i - m) (-32 - 32 n + 24 n ^ 2 - 64 n + 32 r ^ 2 +
8 (9 - 3 m - n (2 m + n) + i (3 + 2 n)) PolyGamma[0,
1/4 (-1 + n)] -
8 (5 i - 5 (5 + m) + 2 i n - 2 m n + n ^ 2) PolyGamma[0, (1 + n)/
4] + 8 (-9 - 3 i + 3 m - 2 i n + 2 m n + n ^ 2) PolyGamma[0,
1/4 + r/2] +
8 (5 i - 5 (5 + m) + 2 i n - 2 m n + n ^ 2) PolyGamma[0,
3/4 + r/2] + (i - m) (-9 + n ^ 2) PolyGamma[1,
1/4 (-1 + n)] + (-i + m) (-25 + n ^ 2) PolyGamma[1, (1 + n)/
4] + (-i + m) (-9 + n ^ 2) PolyGamma[1,
1/4 + r/2] + (i - m) (-25 + n ^ 2) PolyGamma[1, 3/4 + r/2])
``````

Unfortunately, a lot of these sums are en route to IT $$S_n$$ and, finally, keeping track of the PolyGamma term collection becomes too difficult to manipulate for Mathematica and the calculation stagnates.

I am curious to know if there are other methods to evaluate defined amounts of rational functions like mine that could produce cleaner results. I have reviewed some of the software libraries that use the Gosper algorithm and the creative telescoping libraries described here, https://www3.risc.jku.at/research/combinat/software/ergosum/RISC /fastZeil.html, but up to now have not been able to produce a closed form solution.

I would expect that one rational closed form expression exists for $$S_n$$ Based on the above relationship, is there a way to find a regular expression for these sums?

## optimization – algorithm grouping elements (defined by the time range, weight, location) based on the overlap of the time range (groups are limited by parameters)?

Let each element be an individual. Consider that an individual is defined in such a way that each individual has a time range, a weight and a place.

The goal is to group individuals whose time ranges overlap while ensuring that in the group, the sum of the weights of individuals does not exceed a certain threshold. At the same time, it is desirable to minimize the total distance between individuals in the group. As many individuals as needed can be placed in a group as long as the weight constraint is respected.

The goal is to have the largest possible number of individuals grouped (at least in pairs) while minimizing the total distance between individuals in groups.

For example, consider an example in the case of discrete time where there are ten time intervals. [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]. The weight threshold is 4 and the location of individuals are points on the 1-D line of whole numbers.
Let's say we have the following individuals:

``````A: time interval: [1, 2, 3] | weight: 1 | location: 1
B: time interval: [2, 3, 4] | weight: 2 | location: 2
C: time interval: [4, 5, 6] | weight: 2 | location: -3
D: time interval: [4, 5, 6] | weight: 3 | location: -3
``````

Note:

• Groups A and C can not be grouped because they do not overlap.
• the grouping of A and B gives is preferable to the grouping of B and C because A and B are closer.
• Groups C and D can not be grouped because the sum of their weights exceeds 4.
Does any one have a recommended algorithm for solving a problem like this?

I have reviewed the examples of (Studies in Computational Intelligence 666), Michael Mutingi, Charles Mbohwa (AB) – Grouping of Genetic Algorithms – Progress and Applications – Springer International Publishing (2017). However, none of the grouping algorithms seems very appropriate.

## magento2 – main.CRITICAL: The email template & # 39; & # 39; is not defined. at /public_html/vendor/magento/module-email/Model/Template/Config.php:225) "} []]

In my exception.log, this error message appears, I am unable to trace the origin of the exception.

magento: 2.2.6

``````main.CRITICAL: The email template & # 39; & # 39; is not defined. {"exception":"[object] (UnexpectedValueException (code: 0): the email template is not set. At /public_html/vendor/magento/module-email/Model/Model/Config.php:225 ) "} []
``````