How do I... Change a SQL statement depending on a user's selected option

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Hi all,

I am making a map with Carto.js and I am trying to update a SQL query depending on what the user has selected from a dropdown menu. For example, if the user selects "change to fruit production", then the layer's SQL query should change to:

SELECT * FROM indicators WHERE fruit ILIKE 'Yes'

What I have tried:

Carto has recently updated, so there entire .js API formatting has changed. Using their docs, this is how I have added the SQL layer so far:

JavaScript

//Add SQL layer
		const indicatorsSource = new carto.source.SQL(`
		  SELECT *
		    FROM indicators WHERE grain ILIKE 'Yes'     
		`);		

		const indicatorsStyle = new carto.style.CartoCSS(`
		  #layer {
		    polygon-fill: #50ae31;
    		polygon-opacity: 0.65;
		  }
		`);
		const indicators = new carto.layer.Layer(indicatorsSource, indicatorsStyle);

As you can see, I have no idea how to change the feature variable ("grain" in the example) depending on what the user has been selected.

Posted 16-Jun-18 0:18am

Member 13874858

Updated 16-Jun-18 5:12am

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Mike V Baker · Answer 1 · 2018-06-16T05:13:00

Is it the string delimiter that's the issue here? To embed single quotes in a string, use double quote on the extremes of the string.

const indicatorsSource = new carto.source.SQL("
		  SELECT *
		    FROM indicators WHERE grain ILIKE 'Yes'     
		");

However I don't know of a 'grain' named 'Yes'. Grains are wheat, rye, oat. Oh, and now that I think about it... where's the wildcard that LIKE and ILIKE are supposed to use? Getting grain starting with 'w' would be this

const indicatorsSource = new carto.source.SQL("
		  SELECT *
		    FROM indicators WHERE grain ILIKE 'w%'     
		");

Is that more what you're looking for?

HTH,
Mike