使用 Dart/Flutter 查询包含保存在 Cloud Firestore 中的字符串的 Map

Question

I've a problem with a query condition. I would like to query a string inside an array that's also inside a map. I manage to receive the information complet without the where condition but when I do this condition I've an error.

My function to retrieve all information

My array with a map inside

Answer 1

If category is the only value inside the produits array items, you can check for its existence with array-contains :

collectionRef.where('produits', arrayContains({ 'categorie': 'Alimentation' }))

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If there are more properties for the array item, you will need to specify all of them in the call to arrayContains . There is no way to query for a subset of the array item.

In such cases, a common workaround is to add a extra array field to the document with just the property values you want to query for. For example:

produitsCategories: ['Alimentation', '...']

With that field in place you can then query it with:

collectionRef.where('produitsCategories', arrayContains('Alimentation'))