File size: 3,670 Bytes
2fb5c9c | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 | Fix the following issue:
# Fix DataFrame uploads with reserved/geometry columns
Uploading a `pandas`/`geopandas` DataFrame to CARTO via `Dataset(df).upload(...)` is
generating inconsistent and sometimes broken SQL. For example, a DataFrame whose only
columns are `cartodb_id` and `the_geom` ends up producing a `CREATE TABLE` statement with
a dangling leading comma like `CREATE TABLE t (, the_geom geometry(...))`, which the
database rejects. The root cause is that the column list used to create the table, the
column list used in the `COPY` statement, and the values written to each row are all
computed independently and can disagree about how many columns there are and what they are
called.
Make the upload path derive a single, consistent description of the destination columns
from the DataFrame and use it everywhere. The observable behavior of an upload (the
`CREATE TABLE` statement and the `COPY ... FROM stdin` statement together with the rows of
CSV data streamed to the backend) must satisfy the following contract.
## Column selection and ordering
- Every column of the DataFrame is uploaded, in the DataFrame's original column order. In
particular `cartodb_id` is treated as a normal column and is kept.
- A column named `the_geom_webmercator` (matched case-insensitively) is always dropped and
never appears in the table, the `COPY` column list, or the data.
## Geometry handling
- Exactly one column is treated as the geometry. If the DataFrame is a GeoDataFrame with an
active geometry column, that column is used; otherwise the first column whose lower-cased
name is one of `the_geom`, `geom`, `geometry` is used, considered in that order of
priority (so if several are present, `the_geom` wins, then `geom`, then `geometry`).
- The chosen geometry column is named `the_geom` in the destination, declared with type
`geometry(<GeometryType>, 4326)` where `<GeometryType>` is detected from the data (e.g.
`Point`), and its values are emitted as `SRID=4326;<WKT>`. A null/missing geometry value
produces an empty field.
- Any other column that merely happens to be named like a geometry but was not selected as
*the* geometry column is uploaded as an ordinary column: it keeps its (normalized) name
and its value is written verbatim, not re-encoded.
## Ordinary columns
- Non-geometry column names are normalized to SQL-safe names (lower-cased, spaces and other
unsupported characters replaced, etc.) in both the `CREATE TABLE` and the `COPY` column
list. Values are written in their string form; a null value produces an empty field.
- Column SQL types in `CREATE TABLE` are derived from the DataFrame dtypes:
`float64`/`float32` → `numeric`, `int64` → `bigint`, `int32` → `integer`,
`object` → `text`, `bool` → `boolean`, datetime dtypes → `timestamp`; anything else
defaults to `text`.
## `with_lnglat`
- When `with_lnglat=(lng_col, lat_col)` is passed, an extra geometry column named
`the_geom` of type `geometry(Point, 4326)` is appended after the regular columns, built
per row as `SRID=4326;POINT (<lng> <lat>)`. The `lng_col` and `lat_col` columns are still
uploaded as ordinary columns.
- When `with_lnglat` is used, any geometry column that would otherwise have been detected in
the DataFrame is dropped, so the synthesized point is the only geometry uploaded.
## Statement format
The `COPY` statement keeps its existing shape:
```
COPY <table>(<col1>,<col2>,...) FROM stdin WITH (FORMAT csv, DELIMITER '|');
```
with the destination column names joined by commas (no spaces). Each streamed row is the
column values joined by `|` and terminated by a newline, encoded to bytes.
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